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Leishmania donovani surface glycoprotein 63 (GP63) is a major virulence factor involved in parasite escape and immune evasion. In this study, we generated virus-like particles (VLPs) expressing L. donovani GP63 using the baculovirus expression system. Mice were intramuscularly immunized with GP63-VLPs and challenged with L. donovani promastigotes. GP63-VLP immunization elicited higher levels of L. donovani antigen-specific serum antibodies and enhanced splenic B cell, germinal center B cell, CD4+, and CD8+ T cell responses compared to unimmunized controls. GP63-VLPs inhibited the influx of pro-inflammatory cytokines IFN-γ and IL-6 in the livers, as well as thwarting the development of splenomegaly in immunized mice. Upon L. donovani challenge infection, a drastic reduction in splenic parasite burden was observed in VLP-immunized mice. These results indicate that GP63-VLPs immunization conferred protection against L. donovani challenge infection by inducing humoral and cellular immunity in mice. Author summary: Visceral leishmaniasis is a neglected tropical disease that can be fatal in humans if left untreated. Unfortunately, despite the urgent need, an efficacious vaccine for this parasitic disease continues to remain under development. Though challenging, we attempted to develop an experimental leishmaniasis vaccine using the highly immunogenic virus-like particle (VLP) platform that expressed the glycoprotein 63 antigen of Leishmania donovani, a causative agent of visceral leishmaniasis. We used this vaccine to immunize mice and after two immunizations, mice were challenge infected with L. donovani to assess vaccine-induced protection. Our results revealed that compared to the unimmunized control mice, mice immunized with the experimental vaccines were well-protected against developing visceral leishmaniasis. Specifically, VLP vaccine immunization ensured that immune responses necessary for protection were induced to high levels and this contributed to suppressing leishmaniasis-associated pathologies as well as the parasite propagation in mice. Overall, we demonstrated that this VLP-based vaccine can elicit adequate protection against visceral leishmaniasis and propose further research to enhance and optimize its efficacy. [ABSTRACT FROM AUTHOR]

The spleen plays a pivotal role in the pathogenesis of visceral leishmaniasis. In severe forms of the disease, the spleen undergoes changes that can compromise its function in surveilling blood-circulating pathogens. In this study, we present an integrated analysis of the structural and gene expression alterations in the spleens of three patients with relapsing visceral leishmaniasis, two of whom were coinfected with HIV. Our findings reveal that the IL6 signaling pathway plays a significant role in the disorganization of the white pulp, while BCL10 and ICOSLG are associated with spleen organization. Patients coinfected with HIV and visceral leishmaniasis exhibited lower splenic CD4+ cell density and reduced expression of genes such as IL15. These effects may contribute to a compromised immune response against L. infantum in coinfected individuals, further impacting the structural organization of the spleen. Author summary: While most individuals recover after contracting visceral leishmaniasis, there are cases where patients experience a relapsing form of the disease. This response pattern to Leishmania infection is linked to alterations in spleen structure. Until now, these spleen changes had only been examined in dogs and laboratory animals. In our study, we provide data on the disorganization of spleen structure in three patients diagnosed with VL, two of whom were also co-infected with HIV. The observed patterns of spleen disorganization closely resembled those seen in dogs. Our study emphasizes the involvement of IL6, BCL10, and ICOSLG in this process. [ABSTRACT FROM AUTHOR]

American tegumentary leishmaniasis (ATL) diagnosis is an open question, and the search for a solution is urgent. The available tests that detect the etiological agent of the infection are specific for ATL diagnosis. However, they present disadvantages, such as low sensitivity and the need for invasive procedures to obtain the samples. Immunological methods (leishmanin skin test and search for anti-Leishmania antibodies) are good alternatives to the etiological diagnosis of ATL. Presently, we face problems with disease confirmation due to the discontinuity in the production of leishmanin skin test antigen, particularly in resource-poor settings. Aiming to diagnose ATL, we validated rLb6H-ELISA for IgG antibodies using 1,091 samples from leishmaniasis patients and healthy controls, divided into four panels, living in 19 Brazilian endemic and non-endemic states. The rLb6H-ELISA showed a sensitivity of 98.6% and a specificity of 100.0%, with the reference panel comprising 70 ATL patient samples and 70 healthy controls. The reproducibility evaluation showed a coefficient of variation of positive samples ≤ 8.20% for repeatability, ≤ 17,97% for reproducibility, and ≤ 8.12% for homogeneity. The plates sensitized with rLb6H were stable at 4°C and -20°C for 180 days and 37°C for seven days, indicating 12 months of validity. In samples of ATL patients from five research and healthcare centers in endemic and non-endemic areas, rLb6H-ELISA showed a sensitivity of 84.0%; no significant statistical difference was observed among the five centers (chi-square test, p = 0.13). In samples of healthy controls from four areas with different endemicity, a specificity of 92.4% was obtained; lower specificity was obtained in a visceral leishmaniasis high endemicity locality (chi-square test, p<0.001). Cross-reactivity was assessed in 166 other disease samples with a positivity of 13.9%. Based on the good diagnostic performance and the reproducibility and stability of the antigen, we suggest using ELISA-rLb6H to diagnose ATL. [ABSTRACT FROM AUTHOR]

Visceral leishmaniasis (VL) is an infectious disease caused by protozoa, Leishmania. During infection, the cell-mediated immunity of host gets impeded, so immunomodulation using natural products can be considered as an effective therapeutic strategy. The present study deals with the investigation of antileishmanial and immunostimulatory potential of hydro-ethanolic root extract of Rhodiola imbricata (HERERI) in inbred BALB/c mice. The secondary metabolites were analyzed quantitatively. To study the effect of HERERI on promastigotes, assays including inhibitory concentration (IC50) by trypan blue staining, cell cycle arrest by FACS were performed. The splenic parasite load was monitored after 14 days of treatment in BALB/c mice (500 and 1000 mg kg−1 b.wt.). The immunological responses after treatment were recorded in terms of DTH (delayed type of hypersensitivity) reactions, different T lymphocyte's subtypes and amounts of Th1/2 cytokines. Biochemical assays to analyze the function of liver and kidney were also done along with the histological studies. HERERI contains a considerable amount of flavonoids, phenols and terpenoids. The IC50 of 24.84 ± 0.52 and 46.65 ± 1.90 µg mL−1 against sensitive and resistant strain was obtained, respectively. It also arrested the cell cycle of promastigotes at sub G0-G1 phase. HERERI significantly decreased parasite load and up-scaled the DTH responses. It also polarized the Th1 dominating immune status by upregulation of IL-12, IFN-γ, and TNF-α cytokines and CD4+, CD8+ T cells. It caused no toxicity as biochemical tests and the histological sections were normal as compared to infected animals. Overall R. imbricata rescued mice from VL infection through immunostimulation. [ABSTRACT FROM AUTHOR]

Objective: To understand the epidemiological distribution characteristics of mountain-type zoonotic visceral leishmaniasis (MT-ZVL) in Yangquan City, Shanxi Province, China, from 2006 to 2021, to explore the influencing factors leading to the re-emergence of the epidemic, and to provide a basis for the formulation of targeted control strategies. Methods: Case information spanning from 2006 to 2021 in Yangquan City was collected for a retrospective case-control study conducted from June to September 2022. A 1:3 matched ratio was employed. A questionnaire was utilized to gather data on basic information, demographic characteristics, awareness of MT-ZVL knowledge, residence, and dog breeding and living habits. The study employed a multifactorial conditional stepwise logistic regression model to analyze the influencing factors. Results: A total of 508 subjects was analyzed. Risk factors for MT-ZVL included the use of soil/stone/concrete as building materials (OR = 3.932), presence of nearby empty/stone stack houses (OR = 2.515), dog breeding (OR = 4.215), presence of stray dogs (OR = 2.767), and neighbor's dog breeding (OR = 1.953). Protective factors comprised knowledge of MT-ZVL (OR = 0.113) and using mosquito repellents (OR = 0.388). The findings indicate significant associations between environmental and behavioral factors and MT-ZVL incidence in Yangquan City, Shanxi Province, China, from 2006 to 2021. These results underscore the importance of public awareness campaigns and targeted interventions aimed at reducing exposure to risk factors and promoting protective measures to mitigate the re-emergence of MT-ZVL outbreaks. Conclusion: House building materials, presence of neighboring empty houses, breeding domestic dogs and distribution of stray dogs surrounding the home are risk factors for MT-ZVL. Awareness of MT-ZVL and implementation of preventive measures during outdoor activities in summer and autumn are protective and may reduce the risk of MT-ZVL. Author summary: In recent years, a rapid reemergence of mountain-type zoonotic visceral leishmaniasis (MT-ZVL) has been seen in the extension region of the Loess Plateau that had previously achieved elimination in China. In this study, we investigate the epidemiological characteristics of MT-ZVL and identify the factors associated with the rapid rise in MT-ZVL epidemics using a case-control design. A questionnaire was used to collect basic information, demographic characteristics, awareness of MT-ZVL knowledge, residence, and dog breeding and living habits. A multifactorial conditional stepwise logistic regression model was used to analyze the influencing factors. The study revealed that there has been a rising trend in the MT-ZVL endemic areas. House building materials, presence of neighboring empty houses, breeding domestic dogs and distribution of stray dogs surrounding the home are risk factors for MT-ZVL. Awareness of MT-ZVL and implementation of preventive measures during outdoor activities in summer and autumn are protective and may reduce the risk of MT-ZVL. We believe that our study makes a significant contribution to the literature to develop strategy for control the ongoing local transmission of MT-ZVL in hill districts. By analyzing the epidemiological characteristics and influencing factors of MT-ZVL, this research provides a basis for further optimizing the targeted control strategies. [ABSTRACT FROM AUTHOR]

This study investigated the sand fly fauna of the municipality Iguatama, in the Midwest Region of Minas Gerais state, Brazil, including Leishmania infection rates and blood meal sources. Sand flies were collected during four periods over the course of a single year, encompassing both dry and rainy seasons, using CDC light traps placed in peridomiciles where dogs were seropositive for visceral leishmaniasis (VL). A total of 762 sand fly specimens, representing 12 species across seven genera, were collected. Lutzomyia longipalpis was the most abundant species, comprising 57.6% of the collected specimens, followed by Nyssomyia neivai (19.6%) and Nyssomyia whitmani (10.5%). Species richness and diversity varied among collection periods, with the highest diversity observed in January 2019. Molecular analysis detected Leishmania DNA in 12.5% of the sand fly specimens, with Le. infantum being the predominant species. Blood meal analysis revealed feeding on multiple vertebrate species, including humans, rats, dogs, and chickens. The presence of Leishmania DNA in sand flies, and the identification of human blood meals, highlight the potential role of these species in VL transmission. These findings underscore the importance of continued surveillance and control measures to prevent the spread of VL and reduce transmission risk in the region. [ABSTRACT FROM AUTHOR]

Background Neglected tropical diseases are responsible for considerable morbidity and mortality in low-income populations. International efforts have reduced their global burden, but transmission is persistent and case-finding-based interventions rarely target asymptomatic individuals. Methods We develop a generic mathematical modeling framework for analyzing the dynamics of visceral leishmaniasis in the Indian sub-continent (VL), gambiense sleeping sickness (gHAT), and Chagas disease and use it to assess the possible contribution of asymptomatics who later develop disease (pre-symptomatics) and those who do not (non-symptomatics) to the maintenance of infection. Plausible interventions, including active screening, vector control, and reduced time to detection, are simulated for the three diseases. Results We found that the high asymptomatic contribution to transmission for Chagas and gHAT and the apparently high basic reproductive number of VL may undermine long-term control. However, the ability to treat some asymptomatics for Chagas and gHAT should make them more controllable, albeit over relatively long time periods due to the slow dynamics of these diseases. For VL, the toxicity of available therapeutics means the asymptomatic population cannot currently be treated, but combining treatment of symptomatics and vector control could yield a quick reduction in transmission. Conclusions Despite the uncertainty in natural history, it appears there is already a relatively good toolbox of interventions to eliminate gHAT, and it is likely that Chagas will need improvements to diagnostics and their use to better target pre-symptomatics. The situation for VL is less clear, and model predictions could be improved by additional empirical data. However, interventions may have to improve to successfully eliminate this disease. [ABSTRACT FROM AUTHOR]

Introduction: Neglected tropical diseases (NTDs) mainly affect underprivileged populations, potentially resulting in catastrophic health spending (CHS) and impoverishment from out-of-pocket (OOP) costs. This systematic review aimed to summarize the financial hardship caused by NTDs. Methods: We searched PubMed, EMBASE, EconLit, OpenGrey, and EBSCO Open Dissertations, for articles reporting financial hardship caused by NTDs from database inception to January 1, 2023. We summarized the study findings and methodological characteristics. Meta-analyses were performed to pool the prevalence of CHS. Heterogeneity was evaluated using the I2 statistic. Results: Ten out of 1,768 studies were included, assessing CHS (n = 10) and impoverishment (n = 1) among 2,761 patients with six NTDs (Buruli ulcer, chikungunya, dengue, visceral leishmaniasis, leprosy, and lymphatic filariasis). CHS was defined differently across studies. Prevalence of CHS due to OOP costs was relatively low among patients with leprosy (0.0–11.0%), dengue (12.5%), and lymphatic filariasis (0.0–23.0%), and relatively high among patients with Buruli ulcers (45.6%). Prevalence of CHS varied widely among patients with chikungunya (11.9–99.3%) and visceral leishmaniasis (24.6–91.8%). Meta-analysis showed that the pooled prevalence of CHS due to OOP costs of visceral leishmaniasis was 73% (95% CI; 65–80%, n = 2, I2 = 0.00%). Costs of visceral leishmaniasis impoverished 20–26% of the 61 households investigated, depending on the costs captured. The reported costs did not capture the financial burden hidden by the abandonment of seeking healthcare. Conclusion: NTDs lead to a substantial number of households facing financial hardship. However, financial hardship caused by NTDs was not comprehensively evaluated in the literature. To develop evidence-informed strategies to minimize the financial hardship caused by NTDs, studies should evaluate the factors contributing to financial hardship across household characteristics, disease stages, and treatment-seeking behaviors. Author summary: Neglected tropical diseases (NTDs) mainly affect underprivileged populations, potentially resulting in catastrophic health spending (CHS) and impoverishment from out-of-pocket (OOP) costs. This systematic review aimed to summarize the financial hardship caused by NTDs. We found that NTDs lead to a substantial number of households facing financial hardship. CHS risk due to direct OOP costs was relatively low among patients with leprosy (0.0–11.0%), dengue (12.5%), and lymphatic filariasis (0.0–23.0%), and relatively high among patients with Buruli ulcers (45.6%). CHS risk varied widely among patients with chikungunya (11.9–99.3%) and visceral leishmaniasis (24.6–91.8%). Costs of visceral leishmaniasis impoverished 20–26% of 61 households, depending on the costs captured. Nevertheless, financial hardship caused by NTDs was not comprehensively evaluated in the literature. Therefore, to develop evidence-informed strategies to minimize the financial hardship caused by NTDs, studies should evaluate the factors contributing to financial hardship across household characteristics, disease stages, and treatment-seeking behaviors. [ABSTRACT FROM AUTHOR]

Background: Diagnosis of visceral leishmaniasis (VL) in resource-limited endemic regions is currently based on serological testing with rK39 immunochromatographic tests (ICTs). However, rK39 ICT frequently has suboptimal diagnostic accuracy. Furthermore, treatment monitoring and detection of VL relapses is reliant on insensitive and highly invasive tissue aspirate microscopy. Miniature direct-on-blood PCR nucleic acid lateral flow immunoassay (mini-dbPCR-NALFIA) is an innovative and user-friendly molecular tool which does not require DNA extraction and uses a lateral flow strip for result read-out. This assay could be an interesting candidate for more reliable VL diagnosis and safer test of cure at the point of care. Methodology/Principle findings: The performance of mini-dbPCR-NALFIA for diagnosis of VL in blood was assessed in a laboratory evaluation and compared with the accuracy of rK39 ICTs Kalazar Detect in Spain and IT LEISH in East Africa. Limit of detection of mini-dbPCR-NALFIA was 650 and 500 parasites per mL of blood for Leishmania donovani and Leishmania infantum, respectively. In 146 blood samples from VL-suspected patients from Spain, mini-dbPCR-NALFIA had a sensitivity of 95.8% and specificity 97.2%, while Kalazar Detect had a sensitivity of 71.2% and specificity of 94.5%, compared to a nested PCR reference. For a sample set from 58 VL patients, 10 malaria patients and 68 healthy controls from Ethiopia and Kenya, mini-dbPCR-NALFIA had a pooled sensitivity of 87.9% and pooled specificity of 100% using quantitative PCR as reference standard. IT LEISH sensitivity and specificity in the East African samples were 87.9% and 97.4%, respectively. Conclusions/Significance: Mini-dbPCR-NALFIA is a promising tool for simplified molecular diagnosis of VL and follow-up of treated patients in blood samples. Future studies should evaluate its use in endemic, resource-limited settings, where mini-dbPCR-NALFIA may provide an accurate and versatile alternative to rK39 ICTs and aspirate microscopy. Author summary: Visceral leishmaniasis (VL) is a severe infectious disease caused by unicellular parasites of the Leishmania donovani complex. As VL is fatal when left untreated, early and confirmatory laboratory diagnosis is crucial for adequate patient management. However, currently available serological assays, such as the rK39 rapid diagnostic test, fall short in terms of sensitivity and cannot be used for detection of relapsing infections. Therefore, we evaluated an innovative and user-friendly diagnostic assay called mini-dbPCR-NALFIA, which is based on the direct detection of Leishmania kinetoplast DNA in human blood samples. We found that mini-dbPCR-NALFIA can detect down to 500 parasites per millilitre of blood, which is lower than the parasite loads generally seen in untreated VL patients. Furthermore, we assessed the accuracy of mini-dbPCR-NALFIA using a set of Spanish and East-African samples from VL patients and control groups. In the Spanish samples, sensitivity of mini-dbPCR-NALFIA was very high and somewhat better than in the East-African samples. The specificity of mini-dbPCR-NALFIA was excellent in both sample sets. In conclusion, considering its robust performance and simplicity, the mini-dbPCR-NALFIA is a promising diagnostic assay that has the potential to improve VL diagnosis and follow-up of treated patients, especially in resource-limited situations. [ABSTRACT FROM AUTHOR]

A large proportion of HIV-coinfected visceral leishmaniasis (VL-HIV) patients exhibit chronic disease with frequent VL recurrence. However, knowledge on immunological determinants underlying the disease course is scarce. We longitudinally profiled the circulatory cellular immunity of an Ethiopian HIV cohort that included VL developers. We show that chronic VL-HIV patients exhibit high and persistent levels of TIGIT and PD-1 on CD8+/CD8- T cells, in addition to a lower frequency of IFN-γ+ TIGIT- CD8+/CD8- T cells, suggestive of impaired T cell functionality. At single T cell transcriptome and clonal resolution, the patients show CD4+ T cell anergy, characterised by a lack of T cell activation and lymphoproliferative response. These findings suggest that PD-1 and TIGIT play a pivotal role in VL-HIV chronicity, and may be further explored for patient risk stratification. Our findings provide a strong rationale for adjunctive immunotherapy for the treatment of chronic VL-HIV patients to break the recurrent disease cycle. A longitudinal study of the circulatory cellular immunity of individuals co-infected with recurrent visceral leishmaniasis and HIV suggests that T cell unresponsiveness underlies visceral leishmaniasis chronicity. [ABSTRACT FROM AUTHOR]

Visceral leishmaniasis-associated hemophagocytic lymphohistiocytosis (VL-HLH) is indistinguishable from those of HLH of other etiologies due to the overlap symptoms, posing a serious threat to life. In this study, we aimed to provide insights for early diagnosis and improve outcomes in pediatric patients with VL-HLH. We retrospectively analyzed the clinical and laboratory data of 10 pediatric patients with VL-HLH and 58 pediatric patients with Epstein–Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH). The median time from symptom onset to cytopenia in patients with VL-HLH and EBV-HLH was 11 days (interquartile range, 7–15 days) and five days (interquartile range, 3.75–9.25 days) (P = 0.005). Both groups showed liver injury and increased lactate dehydrogenase levels; however the levels of aspartate aminotransferase, alanine aminotransferase, direct bilirubin, and lactate dehydrogenase in patients with VL-HLH were significantly lower than those in patients with EBV-HLH (P < 0.05). The fibrinogen and triglyceride levels were almost normal in VL-HLH patients but were significantly altered in EBV-HLH cases (P < 0.05). The positive rate of first bone marrow microscopy examination, anti-rK39 IgG detection, and blood metagenomic next-generation sequencing was 50%, 100%, and 100%, respectively. After VL diagnosis, eight patients were treated with sodium stibogluconate and two were treated with liposomal amphotericin B. All the patients with VL-HLH recovered. Our study demonstrates that regular triglyceride and fibrinogen levels in pediatric patients with VL-HLH may help in differential diagnosis from EBV-HLH. VL-HLH is milder than EBV-HLH, with less severe liver injury and inflammatory responses, and timely treatment with antileishmanial agents is essential to improve the outcomes of pediatric patients with VL-HLH. [ABSTRACT FROM AUTHOR]

This article explores a case of cutaneous leishmaniasis reactivation in a kidney transplant patient in the Brazilian Amazon. Cutaneous leishmaniasis is a disease that can resurface months or years after the initial infection, leading to severe damage. The patient in this case had a history of the disease and developed symptoms of mucocutaneous leishmaniasis in the nasal cavity after the transplant. The article emphasizes the rarity of this occurrence in transplant patients and discusses other similar cases found in existing literature. It also highlights the importance of early diagnosis, appropriate treatment, and adjusting immunosuppression to improve outcomes and reduce disease severity. The article acknowledges the challenges of controlling the disease, particularly in endemic areas, and the added concern of graft involvement in immunosuppressed patients. [Extracted from the article]

The treatment for visceral leishmaniasis (VL) causes toxicity in patients, entails high cost and/or leads to the emergence of resistant strains. No human vaccine exists, and diagnosis presents problems related to the sensitivity or specificity of the tests. Here, we tested two phage clones, B1 and D11, which were shown to be protective against Leishmania infantum infection in a murine model as immunotherapeutics to treat mice infected with this parasite species. The phages were used alone or with amphotericin B (AmpB), while other mice received saline, AmpB, a wild‐type phage (WTP) or WTP/AmpB. Results showed that the B1/AmpB and D11/AmpB combinations induced polarised Th1‐type cellular and humoral responses, which were primed by high levels of parasite‐specific IFN‐γ, IL‐12, TNF‐α, nitrite and IgG2a antibodies, which reflected in significant reductions in the parasite load in distinct organs of the animals when analyses were performed 1 and 30 days after the treatments. Reduced organic toxicity was also found in these animals, as compared with the controls. In conclusion, preliminary data suggest the potential of the B1/AmpB and D11/AmpB combinations as immunotherapeutics against L. infantum infection. [ABSTRACT FROM AUTHOR]

Apolipoprotein E (ApoE) has been associated with several diseases including Parkinson's disease, Alzheimer's and multiple sclerosis. ApoE also has documented immunomodulatory functions. We investigated gene expression in circulating monocytes and in bone marrows of patients with visceral leishmaniasis (VL) living in an endemic area in Bihar, India, and contrasted these with control healthy subjects or other diagnostic bone marrows from individuals in the same region. Samples from VL patients were obtained prior to initiating treatment. Our study revealed significant upregulated expression of the apoE transcript in patients with VL. Furthermore, the levels of ApoE protein were elevated in serum samples of subjects with VL compared with healthy endemic controls. These observations may provide clues regarding the complex interactions between lipid metabolism and immunoregulation of infectious and inflammatory diseases. [ABSTRACT FROM AUTHOR]

Visceral leishmaniasis (VL) is an infectious disease caused by Leishmania infantum. Clinically, VL evolves with systemic impairment, immunosuppression and hyperactivation with hypergammaglobulinemia. Although renal involvement has been recognized, a dearth of understanding about the underlying mechanisms driving acute kidney injury (AKI) in VL remains. We aimed to evaluate the involvement of immunoglobulins (Igs) and immune complexes (CIC) in the occurrence of AKI in VL patients. Fourteen VL patients were evaluated between early treatment and 12 months post-treatment (mpt). Anti-Leishmania Igs, CIC, cystatin C, C3a and C5a were assessed and correlated with AKI markers. Interestingly, high levels of CIC were observed in VL patients up to 6 mpt. Concomitantly, twelve patients met the criteria for AKI, while high levels of cystatin C were observed up to 6 mpt. Plasmatic cystatin C was positively correlated with CIC and Igs. Moreover, C5a was correlated with cystatin C, CIC and Igs. We did not identify any correlation between amphotericin B use and kidney function markers in VL patients, although this association needs to be further explored in subsequent studies. Our data reinforce the presence of an important renal function impairment during VL, suggesting the involvement of Igs, CIC, and C5a in this clinical condition. [ABSTRACT FROM AUTHOR]

An in‐depth understanding of the mechanism concerning the parasitic disease called visceral leishmaniasis (VL) remains challenging. Thus, we modeled the dynamics of this illness using two fractional‐order operators, including Caputo–Fabrizio and Atangana–Baleanu. In the proposed dynamical model, the endemic and disease‐free equilibrium points were considered the symmetrical components. The fractional Euler method was applied to simulate the developed model, thus determining the equilibrium points' stability. The numerical simulation results were compared with the measured data to validate the model. The results obtained from the optimum fractional operator disclosed the minimum absolute and relative errors. The primary outcome of our study is the successful application of fractional‐order operators, specifically the Atangana–Baleanu operators with α$$ \alpha $$ = 0.98, in modeling the dynamics of VL. Notably, the numerical simulation results, validated against real data from Sudan, demonstrated that the Atangana–Baleanu operators with α$$ \alpha $$ = 0.98 yielded the best performance, with minimum absolute and relative errors. This underscores the precision of our fractional calculus‐based dynamical model in predicting VL dynamics compared to the classical framework, particularly for fractional‐order values of α$$ \alpha $$ = 0.99 and α$$ \alpha $$ = 0.98. [ABSTRACT FROM AUTHOR]

Visceral leishmaniasis (VL) is a potentially fatal parasitic infection caused by Leishmania donovani in India. L. donovani is an obligate intracellular protozoan residing mostly in macrophages of the reticuloendothelial system throughout chronic infection. Monocytic phagocytes are critical in the pathogenesis of different forms of leishmaniasis. Subsets of monocytes are distinguished by their surface markers into CD14+CD16- classical monocytes, CD14+CD16+ intermediate monocytes, and CD16++CD14low non-classical monocyte subsets. During cutaneous leishmaniasis (CL), intermediate monocyte are reported to be a source of inflammatory cytokines IL-1β and TNF, and they express CCR2 attracting them to sites of inflammatory pathology. We examined monocyte subsets in the blood and bone marrow of patients with VL from an endemic site in Bihar, India, and found these contrasted with the roles of monocytes in CL. During VL, intermediate and non-classical CD16+ monocyte subsets expressed instead a non-inflammatory phenotype with low CCR2, high CX3CR1 and low microbicidal oxidant generation, making them more similar to patrolling monocytes than inflammatory cells. Bone marrow CD16+ monocyte subsets expressed a phenotype that might be more similar to the inflammatory subsets of CL, although our inability to obtain bone marrow from healthy donors in the endemic region hampered this interpretation Overall the data suggest that CD16+ intermediate monocyte subsets in VL patients express a phenotypes that contributes to an immunosuppressed pathologic immune state, but in contrast to CL, these do not mediate localized inflammatory responses. Author summary: The parasite Leishmania donovani causes the fatal systemic disease visceral leishmaniasis (VL) in endemic nations including India. The parasite is an obligate intracellular protozoan, residing mostly in monocytic cells in the bone marrow, blood and affected organs of infected human or other vertebrate hosts. Cells of the monocytic lineage can either provide a safe intracellular location in which the parasite survives, or they can be activated to kill intracellular parasites. We studied the contribution of monocyte subsets in the blood and bone marrow of patients from India with active visceral leishmaniasis, or control subjects without leishmaniasis. Our studies suggested that circulating monocytes of patients with VL are defective in their hability to kill intracellular parasites and to migrate toward sites of inflammation. These defects are most prominent in expanded subsets of monocytes expressing both the CD16 and CD14 receptors on their surface membranes. The immune defects underlying VL may be greatly influenced by subsets of blood monocytes that expand during disease. [ABSTRACT FROM AUTHOR]

Background: Currently available treatment options are mostly effective in achieving long-term cure in visceral leishmaniasis (VL) patients. However, there have been reports of recurrence of this illness in both immunosuppressed and immunocompetent patients. Case presentation: We report the first case of recurrent VL relapse in a 19-year-old immunocompetent female with functional hypopituitarism (hypogonadotropic hypogonadism with central hypothyroidism) from Bangladesh, who has been treated three times previously with optimal dosage and duration- liposomal amphotericin B (LAmB) alone and in combination with miltefosine. We treated the patient successfully with a modified treatment regimen of 10 mg/kg body weight LAmB for two consecutive days along with oral miltefosine for seven days as loading dose. For secondary prophylaxis, the patient received 3 mg/kg body weight LAmB along with oral miltefosine for seven days monthly for five doses followed by hormonal replacement. The patient remained relapse free after 12 months of her treatment completion. Conclusion: In the absence of protective vaccines against Leishmania species and standard treatment regimen, this modified treatment regimen could help the management of recurrent relapse cases. Author summary: Visceral leishmaniasis is a globally recognized neglected tropical disease, and Bangladesh is a major contributor of the global burden of this illness. In this article, we present a case on a 19-year-old immunocompetent female with pubertal delay, who has been diagnosed as a case of visceral leishmaniasis for 11 years and presented to us with recurrent relapses despite being treated with standard treatment regimens. The patient also developed functional hypopituitarism due to this chronic illness, which hindered her personal, familial, as well as social life. In scarcity of evidence of a standard treatment regimen for recurrent relapse cases, we treated her with high dose liposomal amphotericin B and miltefosine, along with secondary prophylaxis combining these two drugs with excellent result. Her pubertal delay was also addressed with utmost importance to re-establish her social confidence. This article could encourage physicians to outline an effective regimen to deal with these difficult-to-treat cases. [ABSTRACT FROM AUTHOR]

Introduction: Visceral leishmaniasis (VL), a neglected tropical disease that causes substantial morbidity and mortality, is a serious health problem in Ethiopia. Infections are caused by Leishmania (L.) donovani parasites. Most individuals remain asymptomatic, but some develop VL, which is generally fatal if not treated. We identified the area of Metema-Humera in Northwest Ethiopia as a setting in which we could follow migrant workers when they arrived in an endemic area. The demographic characteristics of this population and factors associated with their risk of asymptomatic infection are poorly characterised. Methods: We divided our cohort into individuals who visited this area for the first time (first comers, FC) and those who had already been in this area (repeat comers, RC). We followed them from the beginning (Time 1, T1) to the end of the agricultural season (Time 2, T2), performing tests for sand fly bite exposure (anti-sand fly saliva antibody ELISA) and serology for Leishmania infection (rK39 rapid diagnostic test and the direct agglutination test) at each time point and collecting information on risk factors for infection. Results: Our results show that most migrant workers come from non-endemic areas, are male, young (median age of 20 years) and are farmers or students. At T1, >80% of them had been already exposed to sand fly bites, as shown by the presence of anti-saliva antibodies. However, due to seasonality of sand flies there was no difference in exposure between FC and RC, or between T1 and T2. The serology data showed that at T1, but not at T2, a significantly higher proportion of RC were asymptomatic. Furthermore, 28.6% of FC became asymptomatic between T1 and T2. Over the duration of this study, one FC and one RC developed VL. In multivariable logistic regression of asymptomatic infection at T1, only age and the number of visits to Metema/Humera were significantly associated with asymptomatic infection. Conclusion: A better understanding of the dynamics of parasite transmission and the risk factors associated with the development of asymptomatic infections and potentially VL will be essential for the development of new strategies to prevent leishmaniasis. [ABSTRACT FROM AUTHOR]

Background: With the current treatment options for visceral leishmaniasis (VL), recrudescence of the parasite is seen in a proportion of patients. Understanding parasite dynamics is crucial to improving treatment efficacy and predicting patient relapse in cases of VL. This study aimed to characterize the kinetics of circulating Leishmania parasites in the blood, during and after different antileishmanial therapies, and to find predictors for clinical relapse of disease. Methods: Data from three clinical trials, in which Eastern African VL patients received various antileishmanial regimens, were combined in this study. Leishmania kinetoplast DNA was quantified in whole blood with real-time quantitative PCR (qPCR) before, during, and up to six months after treatment. An integrated population pharmacokinetic-pharmacodynamic model was developed using non-linear mixed effects modelling. Results: Parasite proliferation was best described by an exponential growth model, with an in vivo parasite doubling time of 7.8 days (RSE 12%). Parasite killing by fexinidazole, liposomal amphotericin B, sodium stibogluconate, and miltefosine was best described by linear models directly relating drug concentrations to the parasite elimination rate. After treatment, parasite growth was assumed to be suppressed by the host immune system, described by an Emax model driven by the time after treatment. No predictors for the high variability in onset and magnitude of the immune response could be identified. Model-based individual predictions of blood parasite load on Day 28 and Day 56 after start of treatment were predictive for clinical relapse of disease. Conclusion: This semi-mechanistic pharmacokinetic-pharmacodynamic model adequately captured the blood parasite dynamics during and after treatment, and revealed that high blood parasite loads on Day 28 and Day 56 after start of treatment are an early indication for VL relapse, which could be a useful biomarker to assess treatment efficacy of a treatment regimen in a clinical trial setting. Author summary: After primary treatment of visceral leishmaniasis (VL), relapse of disease occurs in a proportion of patients. Understanding parasite dynamics is crucial to improving treatment efficacy and predicting disease relapse at an early stage. Leishmania kinetoplast DNA loads in blood from East African VL patients from three clinical trials, treated with five different treatment regimens, were used to develop a semi-mechanistic model to integrate in vivo parasite replication in the host, parasite clearance by different VL drug regimens, and suppression of parasite regrowth by the host immune system after treatment. This model deepened our understanding of the parasite-drug-host interaction and described the in vivo parasite growth rate in human for the first time. Moreover, the model revealed that high blood parasite loads on Day 28 and Day 56 after start of treatment are an early indication for VL relapse, which could serve as a biomarker to predict long-term clinical outcome, an important new tool for optimizing future VL treatment regimens. [ABSTRACT FROM AUTHOR]

In Nepal, visceral leishmaniasis (VL) has been targeted for elimination as a public health problem by 2026. Recently, increasing numbers of VL cases have been reported from districts of doubtful endemicity including hills and mountains, threatening the ongoing VL elimination program in Nepal. We conducted a multi-disciplinary, descriptive cross-sectional survey to assess the local transmission of Leishmania donovani in seven such districts situated at altitudes of up to 1,764 meters in western Nepal from March to December 2019. House-to-house surveys were performed for socio-demographic data and data on past and current VL cases. Venous blood was collected from all consenting individuals aged ≥2 years and tested with the rK39 RDT. Blood samples were also tested with direct agglutination test, and a titer of ≥1:1600 was taken as a marker of infection. A Leishmania donovani species-specific PCR (SSU-rDNA) was performed for parasite species confirmation. We also captured sand flies using CDC light traps and mouth aspirators. The house-to-house surveys documented 28 past and six new VL cases of which 82% (28/34) were without travel exposure. Overall, 4.1% (54/1320) of healthy participants tested positive for L. donovani on at least one serological or molecular test. Among asymptomatic individuals, 17% (9/54) were household contacts of past VL cases, compared to 0.5% (6/1266) among non-infected individuals. Phlebotomus argentipes, the vector of L. donovani, was found in all districts except in Bajura. L. donovani was confirmed in two asymptomatic individuals and one pool of sand flies of Phlebotomus (Adlerius) sp. We found epidemiological and entomological evidence for local transmission of L. donovani in areas previously considered as non-endemic for VL. The national VL elimination program should revise the endemicity status of these districts and extend surveillance and control activities to curb further transmission of the disease. [ABSTRACT FROM AUTHOR]

Leishmania donovani are intracellular, human blood parasites that cause visceral leishmaniasis or kala-azar. Cell-penetrating peptides (CPPs) have been shown to modulate intracellular processes and cargo delivery, whereas host defense peptides (HDPs) promote proliferation of both naïve and antigen activated CD4+ T-cells. We report newly designed tripeptides that were able to trigger proinflammatory cytokine (IL-12 and IFN-γ) secretion by CD4+CD44+ T-cells in response to Leishmania donovani infection. These peptides can be used to induce antigen specific TH1 responses to combat obstacles of cytotoxicity and drug resistance associated with current anti-leishmanial drugs. Furthermore, these peptides can also be used as adjuvants to develop an effective immunoprophylactic approach for immunity restoration against visceral leishmaniasis. [ABSTRACT FROM AUTHOR]

Leishmaniasis is a vector‐borne parasitic disease that possesses high morbidity and a variety of clinical manifestations. Of all the clinical manifestations, visceral leishmaniasis (VL) is the deadliest and its etiological organisms are mainly Leishmania infantum (L. infantum) and Leishmania donovani (L. donovani). In the tropical and subtropical regions, L. infantum is the main causative agent of VL, and it creates a favorable biological milieu in the host through the multifaceted action of its trypanothione reductase (TryR), which mediates the reduction of oxidized trypanothione to its reduced form, leading to the replenishment of the antioxidant capacity of the parasite and detoxifying the reactive oxygen and nitrogen species imposed by the host's immune system. The distinct structural and functional differences of this enzyme compared to its human homologs and its pivotal role in the survival of the parasite have rendered it an attractive target for drug discovery odysseys. Consequently, this study aims to identify potential inhibitors of TryR of L. infantum from Allium sativum (A. sativum) using molecular modeling techniques. The identified compounds were first screened using molecular docking, after which the pharmacokinetics properties of the top‐scoring compounds were further evaluated. Further evaluation of the stability of the complexes of the lead compounds with TryR revealed their relative stability over 100 ns simulation period. Ultimately, the lead compounds namely beta‐sitosterol, (E)‐alpha‐bisabolene, and agapanthagenin were found to possess suitable properties based on the results of this study and can serve as inhibitors of TryR of L. infantum upon further in vitro and in vivo study. [ABSTRACT FROM AUTHOR]

Background: Post-kala-azar dermal leishmaniasis (PKDL) is a dermatosis which can occur after successful treatment of visceral leishmaniasis (VL) and is a public health problem in VL endemic areas. We conducted a systematic scoping review to assess the characteristics of published PKDL clinical studies, understand the scope of research and explore the feasibility and value of developing a PKDL individual patient data (IPD) platform. Methods: A systematic review of published literature was conducted to identify PKDL clinical studies by searching the following databases: PubMed, Scopus, Ovid Embase, Web of Science Core Collection, WHO Global Index Medicus, PASCAL, Clinicaltrials.gov, Ovid Global Health, Cochrane Database and CENTRAL, and the WHO International Clinical Trials Registry Platform. Only prospective studies in humans with PKDL diagnosis, treatment, and follow-up measurements between January 1973 and March 2023 were included. Extracted data includes variables on patient characteristics, treatment regimens, diagnostic methods, geographical locations, efficacy endpoints, adverse events and statistical methodology. Results: A total of 3,418 records were screened, of which 56 unique studies (n = 2,486 patients) were included in this review. Out of the 56 studies, 36 (64.3%) were from India (1983–2022), 12 (21.4%) from Sudan (1992–2021), 6 (10.7%) were from Bangladesh (1991–2019), and 2 (3.6%) from Nepal (2001–2007). Five (8.9%) studies were published between 1981–1990 (n = 193 patients), 10 (17.9%) between 1991–2000 (n = 230 patients), 10 (17.9%) between 2001–2010 (n = 198 patients), and 31 (55.4%) from 2011 onwards (n = 1,865 patients). Eight (14.3%) were randomised clinical trials, and 48 (85.7%) were non-randomised studies. The median post-treatment follow-up duration was 365 days (range: 90–540 days) in 8 RCTs and 360 days (range: 28–2,373 days) in 48 non-randomised studies. Disease diagnosis was based on clinical criterion in 3 (5.4%) studies, a mixture of clinical and parasitological methods in 47 (83.9%) and was unclear in 6 (10.7%) studies. Major drugs used for treatment were miltefosine (n = 636 patients), liposomal amphotericin B (L-AmB) (n = 508 patients), and antinomy regimens (n = 454 patients). Ten other drug regimens were tested in 270 patients with less than 60 patients per regimen. Conclusions: Our review identified studies with very limited sample size for the three major drugs (miltefosine, L-AmB, and pentavalent antimony), while the number of patients combined across studies suggest that the IPD platform would be valuable. With the support of relevant stakeholders, the global PKDL community and sufficient financing, a PKDL IPD platform can be realised. This will allow for exploration of different aspects of treatment safety and efficacy, which can potentially guide future healthcare decisions and clinical practices. Author summary: Post-kala-azar dermal leishmaniasis (PKDL) is a dermatosis which mostly manifests after successful treatment of visceral leishmaniasis (VL) and is characterised by macular, papular, nodular, erythematous, or polymorphic rashes. PKDL is a public health problem in VL endemic areas, as recent infectivity studies show that L. donovani parasites can be found in PKDL lesions and remain infectious to sandfly vectors. There are numerous gaps in our existing knowledge of PKDL, including its pathology, immunology, and risk factors associated with therapeutic outcomes. Currently recommended treatments are either expensive (liposomal amphotericin-B), have raised safety concerns (especially for antimony regimens), or require long treatment duration (e.g. miltefosine). In order to scope the measure of evidence supporting therapeutic efficacy recommendations for PKDL patients, we conducted a systematic literature review. Our systematic review identified 56 PKDL studies describing 2,486 patients, with a majority of the studies (31 studies and 1,865 patients) published from 2010 onwards. The Infectious Diseases Data Observatory (IDDO) already have an established data platform for VL, and the IDDO VL data platform currently hosts a critical mass of data from efficacy trials in VL conducted over the past 20 years. Based on the identified volume of data, with a substantial number of studies being relatively recent, we believe that the establishment of a PKDL data platform is feasible. Creating a platform to facilitate the sharing of the datasets would enable in-depth IPD meta-analyses with existing data to address several knowledge gaps of PKDL and guide future research priorities. With the help of relevant stakeholders, the global PKDL community and sufficient resources, a PKDL data platform can be realised and help address key research gaps. [ABSTRACT FROM AUTHOR]

Visceral leishmaniasis (VL), often referred to as kala-azar, is quite rare in developed countries during pregnancy. Only few studies have evaluated its impact on perinatal outcome. It is caused primarily by Leishmania donovani or Leishmania infantum and presents with a wide spectrum of clinical manifestations from cutaneous ulcers to multisystem disease. Differential diagnosis is challenging as symptoms and signs are insidious, mimicking other diseases. Misdiagnosis can result in severe adverse perinatal outcomes, even maternal/neonatal death. Early treatment with liposomal amphotericin-B (LAmB) is currently the first choice with adequate effectiveness. We report a rare case of VL in a twin pregnancy with onset at the second trimester, presenting with periodic fever with rigors, right flank pain, and gradual dysregulation of all three cell lines. The positive rK39 enzyme-linked immunosorbent assay test confirmed the diagnosis. Treatment with LAmB resulted in clinical improvement within 48 h and in the delivery of two late-preterm healthy neonates with no symptoms or signs of vertical transmission. The one-year follow-up, of the mother and the neonates, was negative for recurrence. To our knowledge, this is the first reported case of VL in a twin pregnancy, and consequently treatment and perinatal outcome are of great importance. [ABSTRACT FROM AUTHOR]

Background: In the Mediterranean basin, three Leishmania species have been identified: L. infantum, L. major and L. tropica, causing zoonotic visceral leishmaniasis (VL), zoonotic cutaneous leishmaniasis (CL) and anthroponotic CL, respectively. Despite animal models and genomic/transcriptomic studies provided important insights, the pathogenic determinants modulating the development of VL and CL are still poorly understood. This work aimed to identify host transcriptional signatures shared by cells infected with L. infantum, L. major, and L. tropica, as well as specific transcriptional signatures elicited by parasites causing VL (i.e., L. infantum) and parasites involved in CL (i.e., L. major, L. tropica). Methodology/Principal findings: U937 cells differentiated into macrophage-like cells were infected with L. infantum, L. major and L. tropica for 24h and 48h, and total RNA was extracted. RNA sequencing, performed on an Illumina NovaSeq 6000 platform, was used to evaluate the transcriptional signatures of infected cells with respect to non-infected cells at both time points. The EdgeR package was used to identify differentially expressed genes (fold change > 2 and FDR-adjusted p-values < 0.05). Then, functional enrichment analysis was employed to identify the enriched ontology terms in which these genes are involved. At 24h post-infection, a common signature of 463 dysregulated genes shared among all infection conditions was recognized, while at 48h post-infection the common signature was reduced to 120 genes. Aside from a common transcriptional response, we evidenced different upregulated functional pathways characterizing L. infantum-infected cells, such as VEGFA-VEGFR2 and NFE2L2-related pathways, indicating vascular remodeling and reduction of oxidative stress as potentially important factors for visceralization. Conclusions: The identification of pathways elicited by parasites causing VL or CL could lead to new therapeutic strategies for leishmaniasis, combining the canonical anti-leishmania compounds with host-directed therapy. Author summary: Leishmaniasis is a zoonosis caused by the intracellular parasite of the genus Leishmania. In the Mediterranean region, the human disease can be present mainly in two forms: cutaneous leishmaniasis (CL) and visceral leishmaniasis (VL), which can be fatal if untreated. The clinical presentation of the disease depends on the parasite species and host characteristics. However, the molecular mechanisms underlying the development of the visceral form of leishmaniasis are not yet fully understood. In this study, we have determined the gene expression profile in cells infected by three Leishmania species (L. infantum, L. major, L. tropica) responsible for different forms of the disease. The results have allowed us to identify an expression profile (and the related pathways) shared by cells infected by all Leishmania species. Aside this common response, we also identified a transcriptional response distinguishing cells infected by L. infantum, L. major or L. tropica, as well as the relevant pathways in which these genes participate. Therefore, our results contribute to the knowledge of the host cell mechanisms that are activated along infection with different Leishmania species causing different forms of the disease and, therefore, may help develop new host-directed therapy for Leishmaniasis. [ABSTRACT FROM AUTHOR]

Background: Leishmaniasis are a group of diseases caused by more than 20 species of the protozoan that are transmitted through the bite of female sand fly. The disease is endemic to 98 countries of the world. It affects most commonly the poorest of the poor and mainly males. Several research has been conducted to propose disease control strategies. Effective medical care, vector control, environmental hygiene, and personal protection are the mainstays of the current preventative and control methods. The mathematical models for the transmission dynamics of the disease studied so far did not consider the sex-biased burden of the disease into consideration. Methodology: Unlike the previous VL works, this study introduces a new deterministic sex-structured model for understanding the transmission dynamics of visceral leishmaniasis. Basic properties of the model including basic reproduction number (R0), and conditions for the existence of backward bifurcation of the model are explored. Baseline parameter values were estimated after the model was fitted to Ethiopia's VL data. Sensitivity analysis of the model was performed to identify the parameters that significantly impact the disease threshold. Numerical simulations were performed using baseline parameter values, and scenario analysis is performed by changing some of these parameters as appropriate. Conclusion: The analysis of the model shows that there is a possibility for a backward bifurcation for R0<1 , which means bringing R0 to less than unity may not be enough to eradicate the disease. Our numerical result shows that the implementation of disease-preventive strategies, as well as effectively treating the affected ones can significantly reduce the disease prevalence if applied for more proportion of the male population. Furthermore, the implementation of vector management strategies also can considerably reduce the total prevalence of the disease. However, it is demonstrated that putting more effort in treating affected reservoir animals may not have any significant effect on the overall prevalence of the disease as compared to other possible mechanisms. The numerical simulation infers that a maximum of 60% of extra preventative measures targeted to only male population considerably reduces the total prevalence of VL by 80%. It is also possible to decrease the total prevalence of VL by 69.51% when up to 50% additional infected males receive treatment with full efficacy. Moreover, applying a maximum of 15% additional effort to reduce the number of vectors, decreases the total VL prevalence by 57.71%. Therefore, in order to reduce the disease burden of visceral leishmaniasis, public health officials and concerned stakeholders need to give more emphasis to the proportion of male humans in their intervention strategies. [ABSTRACT FROM AUTHOR]

Maintenance chemotherapy is a standard treatment in patients with non-progressive advance staged IV non-squamous non-small cell lung cancer after induction therapy. Here, we report the case of a 53-year-old man undergoing a maintenance monotherapy with pemetrexed who presented prolonged pancytopenia despite filgrastim injections. A bone marrow aspiration revealed a macrophage activation syndrome with Leishmania amastigotes. A Polymerase Chest Reaction testing confirmed the diagnosis of visceral leishmaniasis. Treatment with liposomal amphotericin B was started. Oncologists should bear in mind that visceral leishmaniasis in endemic areas can potentially induce severe and prolonged pancytopenia in immunosuppressed patients, during chemotherapy in particular. [ABSTRACT FROM AUTHOR]

Leishmaniasis refers to a disease with a wide range of manifestations; and there are three main forms of disease, cutaneous, mucocutaneous, and visceral. Leishmaniasis is one of the diseases with a protozoan agent which is vector-borne. Visceral leishmaniasis (VL) is the most severe form that can be fiercely life-threatening if left untreated. VL can be caused by members of Leishmania donovani complex, in Iran, Leishmania infantum is considered the primary causative agent of VL, resulting in a zoonotic form of VL. The two main goals of our work, which followed our prior sero-epidemiological and entomological survey, were to characterize and conduct a phylogenetic analysis of the Leishmania species that infect people, dogs, and sandflies. The samples were collected throughout 2017, from January to December, so blood samples were collected from humans and dogs, while sandfly samples were collected with sticky traps. DNA extracted from all seropositive samples of humans and dogs, 10% of sero-negative human samples, and all collected sandflies were subjected to kDNA-nested-PCR for tracing parasites. A total of 30 samples, including 20 human samples, 8 dog samples, and 2 sandfly samples, were found positive for the kDNA gene of L. infantum. Sequences were evaluated to study the genetic diversity among the six discovered L. infantum. Based on kDNA, the phylogenetic study of L. infantum demonstrated a high level of genetic variety and a relationship between the host, the parasite's geographic origin, and its genetic diversity. [ABSTRACT FROM AUTHOR]

Background: Visceral leishmaniasis (VL), or kala-azar, is a common comorbidity in patients with AIDS in endemic areas. Many patients continue to experiences relapses of VL despite virological control, but with immunological failure. These patients remain chronically symptomatic with hypersplenism, for example with anemia, leukopenia, and thrombocytopenia, and are at risk of severe co-infection due to low CD4+ count. Therefore, in this study, splenectomized patients with VL and HIV infection were investigated to understand why the CD4+ count fails to recover in these patients, evaluating the importance of spleen mass for hypersplenism and immunological failure. Methods: From a retrospective open cohort of 13 patients who had previously undergone splenectomy as salvage therapy for relapsing VL, 11 patients with HIV infection were investigated. This study compared the patients' complete blood cell count (CBC) and CD4+ and CD8+ cell counts before and after splenectomy with respect to spleen weight. Results: CBC was substantially improved after splenectomy, indicating hypersplenism. However, to the best of our knowledge, this is the first study to show that spleen mass is strongly and negatively correlated with CD4+ cell count (ρ = −0.71, P = 0.015). Conclusions: This finding was unexpected, as the spleen is the most extensive lymphoid tissue and T-lymphocyte source. After reviewing the literature and reasoning, we hypothesized that the immunological failure was secondary to CD4+ loss initially by apoptosis in the spleen induced by productive HIV infection and, subsequently, by pyroptosis sustained by parasitic infection in spleen macrophages. [ABSTRACT FROM AUTHOR]

Background: India is going through the maintenance phase of VL elimination programme which may be threatened by the persistence of hidden parasite pools among asymptomatic leishmanial infection (ALI) and PKDL. The present work was designed to determine the burden of VL, PKDL, and ALI and to assess the role of treatment of ALI in maintaining post-elimination phase. Methods and finding: The study was undertaken in Malda district, West Bengal, India during October 2016 to September 2021. Study areas were divided into 'Study' and 'Control' arms. VL and PKDL cases of both the arms were diagnosed by three active mass surveys with an interval of one year and treated as per National guideline. ALI of study arm was treated like VL. ALI of control arm was followed up to determine their fate. Fed sand-fly pools were analysed for parasitic DNA. No significant difference was noted between the incidence of VL and PKDL in both the arms. Incidence of ALI declined sharply in study arm but an increasing trend was observed in control arm. Significantly higher rate of sero-conversion was noted in control arm and was found to be associated with untreated ALI burden. Parasitic DNA was detected in 22.8% ALI cases and 2.2% sand-fly pools. Conclusion: Persistence of a significant number of PKDL and ALI and ongoing transmission, as evidenced by new infection and detection of leishmanial DNA in vector sand-flies, may threaten the maintenance of post-elimination phase. Emphasis should be given for elimination of pathogen to prevent resurgence of VL epidemics. Author summary: The present study was conducted in a kala-azar endemic block of Malda district, West Bengal. The study areas were divided 'Study' and 'Control' arm and three active mass survey was conducted for detection of visceral leishmaniasis (VL), post kala-azar dermal leishmaniasis (PKDL) and asymptomatic leishmanial infection (ALI). In the study arm, diagnosed ALI cases were treated with Liposomal Amphotericin B. No significant difference was noted between the incidence of VL and PKDL cases in 'Study' and 'Control' arm. But the incidence of ALI cases declined sharply in 'Study' arm and increasing trend was observed in 'Control' arm. A significantly higher rate of ser-conversion was noted in 'Control' arm. In both 'Study' and 'Control' arm, the sero-conversion rate was significantly associated with untreated ALI burden. Persistence of significant number of PKDL and ALI and ongoing transmission as evidenced by new infection and detection of leishmanial DNA in sand-flies may jeopardise the maintenance of post-elimination phase. Therefore, constant vigilance is highly needed to prevent resurgence of VL epidemic. Detection and long-term follow-up of ALI may also help to sustain the elimination. However, feasibility and cost-effectiveness study for detection and treatment of ALI should also receive attention. [ABSTRACT FROM AUTHOR]

Background: Visceral leishmaniasis (VL), or kala-azar, is a vector-borne tropical disease caused by a group of intracellular hemoflagellate protozoa belonging to the family of Trypanosomatide and the genus Leishmania. The disease is distributed around the world and transmitted via the bite of infected female Phlebotomine sandflies, and there is variation in the diagnostic accuracy. Therefore, this systematic review and meta-analysis aimed to determine the pooled global sensitivity and specificity of the rk-39 test and to evaluate if there is a difference between the different parts of the world. Methods: A systematic review and meta-analysis have been conducted on the diagnostic accuracy of dermoscopy. After setting eligibility criteria, literature was searched in four databases and one searching engine. Articles were screened, critically appraised, and extracted independently by two reviewers, and any disagreements were resolved with the involvement of a third person. The quality of the included studies had been assessed by the Quality Assessment of Diagnostic Accuracy Studies (QUADAS 2) tool. Pooled sensitivity and specificity were determined by bivariate random effect analysis. Heterogeneity was assessed by Higgins's I2, and when it was present, mitigation was conducted by using sensitivity analysis. Result: A total of 409 studies were identified, and finally 18 articles were eligible for the review with a total sample size of 5, 253. The bivariate random effect meta-analysis of the 7 diagnostic accuracy studies showed a pooled sensitivity of 0.89 (0.76–0.95) and specificity of 0.86 (0.72–0.94). The +LR was 6.32 (95% CI: 2.85–14.02), the–LR was 0.13 (95% CI: 0.06–0.30), and the diagnostic odds ratio (DOR) was 47.8 (95% CI: 11.3–203.2). Abdel-Latif (2018) was both an outlier and influential for sensitivity, and Walter (2011) was both an outlier and influential for specificity, and removing them from sensitivity and specificity, respectively, was beneficial for reducing the heterogeneity. Conclusion: Rk-39 is found to have highly accurate measures in the diagnosis of visceral leishmaniasis. Both sensitivity and specificity were found to be highly accurate in the diagnosis of leishmaniasis, with a pooled sensitivity of 0.91 (0.88–0.93) and a pooled specificity of 0.89 (0.85–0.91). Ethical consideration: As we will use secondary data for the systematic review and meta-analysis, ethical concerns are not necessary. Author summary: Leishmaniasis is a vector-borne tropical disease distributed around the world and transmitted via the bite of infected sandflies. There are 3 main forms of the disease: visceral leishmaniasis, which is fatal if left untreated in over 95% of cases and is characterized by irregular bouts of fever, weight loss, enlargement of the spleen and liver, and anemia. The other form of the disease is cutaneous leishmaniasis, which causes skin lesions and life-long scars on exposed parts of the body. Whereas the third one, mucocutaneous leishmaniasis, leads to partial or total destruction of the mucous membranes of the nose, mouth and throat. In this study, the authors examined the distribution of visceral leishmaniasis, which has significant impact on livelihoods such as agriculture and livestock and affects cognitive, developmental and educational outcomes. Moreover, since visceral leishmaniasis is a killer disease, timely and accurate diagnosis is important to give appropriate treatment. This systematic review and meta-analysis identify the pooled sensitivity and specificity of the rk-39 test regarding its accuracy by considering many studies in the different parts of the world. According to our findings, rk-39 is regarded as a crucial quick diagnostic tool for the diagnosis of visceral leishmaniasis. [ABSTRACT FROM AUTHOR]

Aims: This study describes the spatio‐temporal dynamics of new visceral leishmaniasis (VL) cases notified in Brazil between 2001 and 2020. Methods and Results: Data on the occurrence of the disease were obtained by means of the Notifiable Diseases Information System of the Brazilian Ministry of Health. Joinpoint, temporal generalized additive models and conditional autoregressive (CAR) models were used to analyse the temporal evolution of the rates in Brazil, states and regions. Spatio‐temporal generalized additive and CAR models were used to identify the distribution of annual risks of VL occurrence in the Brazilian territory in relation to variation in the spatial average. There were 63,966 VL cases in the target period (3.198 cases/year), corresponding to a mean incidence rate of 1.68 cases/100,000 inhabitants. Of these, 4451 resulted in deaths, which gives a mean mortality rate of 0.12 deaths/100,000 inhabitants and a case fatality of 6.96%. The highest incidence rate was found in the North region, followed closely by the Northeast region, which presented the second and first highest mortality rates, respectively. For all of Brazil, and in the Northeast region, there were stability in the incidence rates, while the other regions showed an increasing trend in different time segments in the period: Central‐West up to 2011, North up to 2008, Southeast up to 2004, and South up to 2010. On the other hand, all regions experienced a reduction in incidence rate during the last years of the series. The Northeast region had the highest number of municipalities with statistically significant elevated relative risks. The spatio‐temporal analysis showed the highest risk area predominantly in the Northeast region in the beginning of the time series. From 2002 to 2018, this area expanded to the interior of the country. Conclusions: The present study has shown that VL has expanded in Brazil. However, the North and Northeast regions continue to have the highest incidence, and the risk of infection has decreased in recent years. [ABSTRACT FROM AUTHOR]

Background: Visceral leishmaniasis (VL) resolution depends on a wide range of factors, including the instauration of an effective treatment coupled to a functional host immune system. Patients with a depressed immune system, like the ones receiving methotrexate (MTX), are at higher risk of developing VL and refusing antileishmanial drugs. Moreover, the alarmingly growing levels of antimicrobial resistance, especially in endemic areas, contribute to the increasing the burden of this complex zoonotic disease. Principal findings: To understand the potential links between immunosuppressants and antileishmanial drugs, we have studied the interaction of antimony (Sb) and MTX in a Leishmania infantum reference strain (LiWT) and in two L. infantum clinical strains (LiFS-A and LiFS-B) naturally circulating in non-treated VL dogs in Spain. The LiFS-A strain was isolated before Sb treatment in a case that responded positively to the treatment, while the LiFS-B strain was recovered from a dog before Sb treatment, with the dog later relapsing after the treatment. Our results show that, exposure to Sb or MTX leads to an increase in the production of reactive oxygen species (ROS) in LiWT which correlates with a sensitive phenotype against both drugs in promastigotes and intracellular amastigotes. LiFS-A was sensitive against Sb but resistant against MTX, displaying high levels of protection against ROS when exposed to MTX. LiFS-B was resistant to both drugs. Evaluation of the melting proteomes of the two LiFS, in the presence and absence of Sb and MTX, showed a differential enrichment of direct and indirect targets for both drugs, including common and unique pathways. Conclusion: Our results show the potential selection of Sb-MTX cross-resistant parasites in the field, pointing to the possibility to undermine antileishmanial treatment of those patients being treated with immunosuppressant drugs in Leishmania endemic areas. Author summary: Visceral leishmaniasis (VL) is the most severe form of the disease caused by the parasite Leishmania infantum. Immunosuppressive conditions such as those generated using immunosuppressive treatments (i.e., methotrexate), to treat autoimmune diseases have increased the risk of developing severe complications linked to this parasitic disease, especially in endemic areas. Of note, treatment of VL in immunosuppressed patients is very challenging and frequently results in clinical relapse. For these reasons, it is capital to better understand any potential impact of the use of immunosuppressants on the antileishmanial effect of current drugs (i.e. antimonials) and their potential contribution to the emergence and spread of drug resistance. Here we report the first evidence of the potential co-selection of antimicrobial resistance between antimonials and methotrexate in L. infantum circulating strains. In addition to shedding some light on the causes of treatment failure and relapses in patients under methotrexate immunosuppression, this new knowledge could assist in the development of better immunosuppression strategies in endemic areas of leishmaniasis. [ABSTRACT FROM AUTHOR]

Background: CD4+ T cells play a central role in control of L. donovani infection, through IFN-γ production required for activation of macrophages and killing of intracellular parasites. Impaired control of parasites can in part be explained by hampered CD4+ T cells effector functions in visceral leishmaniasis (VL) patients. In a recent studies that defined transcriptional signatures for CD4+ T cells from active VL patients, we found that expression of the IL-7 receptor alpha chain (IL-7Rα; CD127) was downregulated, compared to CD4+ T cells from endemic controls (ECs). Since IL-7 signaling is critical for the survival and homeostatic maintenance of CD4+ T cells, we investigated this signaling pathway in VL patients, relative to ECs. Methods: CD4+ T cells were enriched from peripheral blood collected from VL patients and EC subjects and expression of IL7 and IL7RA mRNA was measured by real time qPCR. IL-7 signaling potential and surface expression of CD127 and CD132 on CD4+ T cell was analyzed by multicolor flow cytometry. Plasma levels of soluble IL-7 and sIL-7Rα were measured by ELISA. Result: Transcriptional profiling data sets generated previously from our group showed lower IL7RA mRNA expression in VL CD4+ T cells as compared to EC. A significant reduction was, however not seen when assessing IL7RA mRNA by RT-qPCR. Yet, the levels of soluble IL-7Rα (sIL-7Rα) were reduced in plasma of VL patients compared to ECs. Furthermore, the levels of soluble IL-7 were higher in plasma from VL patients compared to ECs. Interestingly, expression of the IL-7Rα protein was higher on VL patient CD4+ T cells as compared to EC, with activated CD38+ CD4+ T cells showing higher surface expression of IL-7Rα compared to CD38- CD4+ T cells in VL patients. CD4+ T cells from VL patients had higher signaling potential baseline and after stimulation with recombinant human IL-7 (rhIL-7) compared to EC, as measured by phosphorylation of STAT5 (pSTAT5). Interestingly, it was the CD38 negative cells that had the highest level of pSTAT5 in VL patient CD4+ T cells after IL-7 stimulation. Thus, despite unaltered or potentially lowered IL7RA mRNA expression by CD4+ T cells from VL patients, the surface expression of the IL-7Rα was higher compared to EC and increased pSTAT5 was seen following exposure to rhIL-7. Accordingly, IL-7 signaling appears to be functional and even enhanced in VL CD4+ T cells and cannot explain the impaired effector function of VL CD4+ T cells. The enhanced plasma IL-7 may serve as part of homeostatic feedback mechanism regulating IL7RA expression in CD4+ T cells. Author summary: In visceral leishmaniasis (VL), antigen specific CD4+ T cell responses are muted hindering the control of the Leishmania donovani infection. IL-7 signaling is crucial for CD4+ T cell survival and function, and gene expression analysis indicated that the IL-7 pathway could be altered in VL. Thus, we investigate if impaired IL-7 signaling could explain the loss of antigen specific T cell response in VL. Although we didn't observe significant reduction of IL7RA mRNA by RT-qPCR, yet, the levels of soluble IL-7Rα (sIL-7Rα) were reduced in plasma of VL patients compared to ECs. Furthermore, the levels of soluble IL-7 were higher in plasma from VL patients compared to ECs and their CD4+ T cells exhibited heightened IL-7 receptor protein expression. Surprisingly, VL patient CD4+ T cells showed increased IL-7 signaling potential, as evidenced by higher phosphorylation of STAT5 upon IL-7 stimulation. While altered, the findings presented here do not attributed the impaired effector function of VL CD4+ T cells to defective IL-7 signaling. We speculate that the elevated plasma IL-7 is part of a homeostatic feedback mechanism in response to the reduced IL7RA transcription in CD4+ T cells. [ABSTRACT FROM AUTHOR]

Lipids stored in lipid-bodies (LBs) in host cells are potential sources of fatty acids for pathogens. However, the mechanism of recruitment of LBs from the host cells by pathogens to acquire fatty acids is not known. Here, we have found that Leishmania specifically upregulates the expression of host Rab18 and its GEF, TRAPPC9 by downregulating the expression of miR-1914-3p by reducing the level of Dicer in macrophages via their metalloprotease gp63. Our results also show that miR-1914-3p negatively regulates the expression of Rab18 and its GEF in cells. Subsequently, Leishmania containing parasitophorous vacuoles (Ld-PVs) recruit and retain host Rab18 and TRAPPC9. Leishmania infection also induces LB biogenesis in host cells and recruits LBs on Ld-PVs and acquires FLC12-labeled fatty acids from LBs. Moreover, overexpression of miR-1914-3p in macrophages significantly inhibits the recruitment of LBs and thereby suppresses the multiplication of parasites in macrophages as parasites are unable to acquire fatty acids. These results demonstrate a novel mechanism how Leishmania acquire fatty acids from LBs for their growth in macrophages. Author summary: Leishmania donovani which causes fatal disease known as visceral leishmaniasis, is dependent on its host to scavenge fatty acids for its survival. But, how Leishmania get fatty acids from host macrophages is not known. Lipid bodies are unique organelles that contain neutral lipids and fatty acids, therefore, LBs in macrophages could be the potential source of fatty acids for parasites. We have found that Leishmania upregulate the expression of host Rab18 and its GEF by downregulating the expression of miR-1914-3p in infected macrophages via the Ld-gp63-mediated inhibition of dicer expression. As biogenesis of LBs is shown to be regulated by Rab18, we have found that Leishmania infection induces LB biogenesis in macrophages and subsequently recruits LBs along with Rab18 and its GEF on Leishmania containing parasitophorous vacuoles. Finally, parasites-containing vacuoles acquire FLC12-labeled fatty acids from LBs to meet their nutritional requirement. We have also shown that overexpression of miR-1914-3p in macrophages significantly inhibits the recruitment of LBs and thereby suppresses the growth of parasites in macrophages as parasites are unable to acquire nutrients from LBs. These results demonstrate how Leishmania acquire nutrients like fatty acids from LBs for their proliferation in macrophages. [ABSTRACT FROM AUTHOR]

The host immune system plays a significant role in managing and clearing pathogen material during an infection, but this complex process presents numerous challenges from a modeling perspective. There are many mathematical and statistical models for these kinds of processes that take into account a wide range of events that happen within the host. In this work, we present a Bayesian joint model of longitudinal and time-to-event data of Leishmania infection that considers the interplay between key drivers of the disease process: pathogen load, antibody level, and disease. The longitudinal model also considers approximate inflammatory and regulatory immune factors. In addition to measuring antibody levels produced by the immune system, we adapt data from CD4+ and CD8+ T cell proliferation, and expression of interleukin 10, interferon-gamma, and programmed cell death 1 as inflammatory or regulatory factors mediating the disease process. The model is developed using data collected from a cohort of dogs naturally exposed to Leishmania infantum. The cohort was chosen to start with healthy infected animals, and this is the majority of the data. The model also characterizes the relationship features of the longitudinal outcomes and time-to-death due to progressive Leishmania infection. In addition to describing the mechanisms causing disease progression and impacting the risk of death, we also present the model's ability to predict individual trajectories of Canine Leishmaniosis (CanL) progression. The within-host model structure we present here provides a way forward to address vital research questions regarding the understanding of the progression of complex chronic diseases such as Visceral Leishmaniasis, a parasitic disease causing significant morbidity worldwide. [ABSTRACT FROM AUTHOR]

Background: As of 2021, the National Kala-azar Elimination Programme (NKAEP) in India has achieved visceral leishmaniasis (VL) elimination (<1 case / 10,000 population/year per block) in 625 of the 633 endemic blocks (subdistricts) in four states. The programme needs to sustain this achievement and target interventions in the remaining blocks to achieve the WHO 2030 target of VL elimination as a public health problem. An effective tool to analyse programme data and predict/ forecast the spatial and temporal trends of VL incidence, elimination threshold, and risk of resurgence will be of use to the programme management at this juncture. Methodology/principal findings: We employed spatiotemporal models incorporating environment, climatic and demographic factors as covariates to describe monthly VL cases for 8-years (2013–2020) in 491 and 27 endemic and non-endemic blocks of Bihar and Jharkhand states. We fitted 37 models of spatial, temporal, and spatiotemporal interaction random effects with covariates to monthly VL cases for 6-years (2013–2018, training data) using Bayesian inference via Integrated Nested Laplace Approximation (INLA) approach. The best-fitting model was selected based on deviance information criterion (DIC) and Watanabe-Akaike Information Criterion (WAIC) and was validated with monthly cases for 2019–2020 (test data). The model could describe observed spatial and temporal patterns of VL incidence in the two states with widely differing incidence trajectories, with >93% and 99% coverage probability (proportion of observations falling inside 95% Bayesian credible interval for the predicted number of VL cases per month) during the training and testing periods. PIT (probability integral transform) histograms confirmed consistency between prediction and observation for the test period. Forecasting for 2021–2023 showed that the annual VL incidence is likely to exceed elimination threshold in 16–18 blocks in 4 districts of Jharkhand and 33–38 blocks in 10 districts of Bihar. The risk of VL in non-endemic neighbouring blocks of both Bihar and Jharkhand are less than 0.5 during the training and test periods, and for 2021–2023, the probability that the risk greater than 1 is negligible (P<0.1). Fitted model showed that VL occurrence was positively associated with mean temperature, minimum temperature, enhanced vegetation index, precipitation, and isothermality, and negatively with maximum temperature, land surface temperature, soil moisture and population density. Conclusions/significance: The spatiotemporal model incorporating environmental, bioclimatic, and demographic factors demonstrated that the KAMIS database of the national programmme can be used for block level predictions of long-term spatial and temporal trends in VL incidence and risk of outbreak / resurgence in endemic and non-endemic settings. The database integrated with the modelling framework and a dashboard facility can facilitate such analysis and predictions. This could aid the programme to monitor progress of VL elimination at least one-year ahead, assess risk of resurgence or outbreak in post-elimination settings, and implement timely and targeted interventions or preventive measures so that the NKAEP meet the target of achieving elimination by 2030. Author summary: In India, VL has been endemic in four states (Bihar, Jharkhand, Uttar Pradesh, and West Bengal), having over 165 million population. The national programme achieved elimination (<1 case / 10,000 population/year per 'block') in 625 of the 633 endemic blocks in 2021. While sustaining elimination level, the programme needs to target other blocks yet to reach elimination to achieve the WHO 2030 target. We fitted a variety of spatiotemporal models to 72-monthly reported VL cases (2013–2018, training period) from 491 endemic and 27 non-endemic blocks in Bihar and Jharkhand. The best fitting model was validated with 24-month reported cases (2019–2020, test period). Model predictions agree with >93 and 99% of the monthly-observations for the periods. Forecasting for 2021–2023 showed that incidence is likely to exceed elimination threshold in 16–18 and 33–38 historically high endemic blocks of Jharkhand and Bihar. Fitted model showed that VL incidence is positively associated with mean temperature, minimum temperature, enhanced vegetation index, precipitation, and isothermality, and negatively with maximum temperature, land surface temperature, soil moisture and population density. Forecasting VL incidence at block level can aid to monitor elimination progress, target the blocks yet to reach elimination and long-term monitoring of risk of resurgence during post-elimination. [ABSTRACT FROM AUTHOR]

Canine visceral leishmaniasis is a parasitic zoonosis that has a profound impact on public health in countries where it is endemic. Chemotherapeutic treatments cannot keep dogs stable for long periods, and the risk of generating parasitic resistance must be considered. Forty‐four symptomatic and naturally infected dogs with Leishmania infantum were tested with two treatment protocols (i) immunotherapy with LaSap vaccine and (ii) immunochemotherapy with LaSap vaccine plus allopurinol. At 90 days after the end of the treatment, it was verified that, although both protocols had generated significant clinical improvements with a greater production of IFN‐γ/IL‐10, in relation to the parasite load, mainly in the skin, the dogs treated only with immunotherapy maintained the same profile. These results indicate that LaSap is a good strategy to control dog parasitism. [ABSTRACT FROM AUTHOR]

Objectives: Visceral leishmaniasis (VL) represents the most severe form of Leishmaniasis infection, often resulting in fatality without timely treatment. Previous studies have found that immunosuppression increases the risk of VL disease progression and mortality, and the total immunoglobulin G (IgG) levels in peripheral blood vary before and after treatment. However, the distinct levels and roles of IgG subclasses in VL have not been documented yet. This study aims to elucidate the characteristics and clinical significance of IgG subclasses in VL. Methods: A total of 43 cases newly‐diagnosed with VL were enrolled in the cohort. We measured the levels of IgG subclasses before and after standard treatment and conducted assessments of bone marrow features. In addition, we analysed other haematological indices and examined the variations in IgG subclasses, as well as their correlation with clinical and laboratory factors. Results: The levels of total IgG, IgG1, and the ratios of both IgG1/IgG and IgG1/IgG2 decreased significantly after treatment, whereas the ratios of IgG2/ IgG showed an obvious increase. The VL patients without hyperglobulinemia displayed significant lower IgG1/IgG2 ratios, but higher IgG2/IgG ratios compared with those with hyperglobulinemia. In addition, VL patients with positive bone marrow amastigotes had significant higher IgG1/IgG and IgG1/IgG2 ratios, but lower IgG2/IgG ratios. IgG subclasses were correlated with abnormal blood test results, particularly immunological elements including IgM and Complement 4 (C4). Conclusions: IgG1 and IgG2 exhibited contrasting changes after treatment in VL patients. The features of bone marrow and laboratory tests indicated that IgG1 and IgG2 serve different roles in the progression of VL. The ratios of IgG subclasses may be more precise indicators to evaluate immune reaction in VL than traditional total IgG. [ABSTRACT FROM AUTHOR]

The aim of the study was to assess the impact of the COVID-19 pandemic on the notification of new VL cases in Brazil in 2020. It is an ecological and time-series study (2015–2020) with spatial analysis techniques, whose units of analysis were the 5570 Brazilian municipalities. The study population consisted of all new cases of VL recorded between 2015 and 2020. The P-score was calculated to estimate the percentage variation in new VL cases. Global and local univariate Moran's Indices and retrospective space–time scan statistics were used in spatial and space–time analyses, respectively. It was expected that there would be 3627 new cases of VL in Brazil in 2020, but 1932 cases were reported (−46.73%). All Brazilian regions presented a negative percentage variation in the registration of new VL cases, with the Southeast (−54.70%), North (−49.97%), and Northeast (−44.22%) standing out. There was spatial dependence of the disease nationwide in both periods, before and during the first year of the COVID-19 pandemic. There was a significant reduction in the incidence of new VL cases in Brazil during the first year of the COVID-19 pandemic. These findings reinforce the need for better preparedness of the health system, especially in situations of new epidemics. [ABSTRACT FROM AUTHOR]

Background: Iran is a country with a high prevalence of visceral leishmaniasis (VL) and seven endemic provinces. In this study, we tried to identify unobserved classes of knowledge among Iranians toward VL and assess the predictors of each latent class. Methods: This cross-sectional study was conducted among randomly selected participants from endemic and non-endemic areas of VL in Iran in 2020 and 2021. The collected data included demographic characteristics and questions about knowledge, attitude, and practice toward VL. We performed latent class analysis using a procedure for latent class analysis (PROC LCA) in SAS to identify the class membership of knowledge of participants toward VL. Results: Five latent classes were identified: very low (38.9%), low (15.5%), moderate (6.2%), high (14.1%), and very high (25.2%) knowledge about VL. Living in endemic areas significantly increased the odds of belonging to the low (adjusted OR (AOR = 7.23; 95% confidence interval (CI):4.52–11.58), high (AOR = 2.71; 95%CI: 1.73–4.23), and very high (AOR = 8.47; 95%CI: 5.78–12.41) classes compared to the very low class. Also, having academic education increased the odds of membership in the very high class (AOR = 2.36; 95%CI: 1.61–3.47) compared to the very low class. Conclusion: This study revealed that more than 50% of the participants fell into the latent classes of very low and low knowledge toward VL. Some educational workshops in the endemic areas could be effective in enhancing knowledge about VL. [ABSTRACT FROM AUTHOR]

Domestic dogs are the primary urban reservoirs of Leishmania infantum, the causative agent of visceral leishmaniasis. In Canine Leishmaniasis (CanL), modulation of the host's immune response may be associated with the expression of small non-coding RNAs called microRNA (miR). miR-194 expression increases in peripheral blood mononuclear cells (PBMCs) of dogs with leishmaniasis with a positive correlation with the parasite load and in silico analysis demonstrated that the TRAF6 gene is the target of miR-194 in PBMCs from diseased dogs. Here, we isolated PBMCs from 5 healthy dogs and 28 dogs with leishmaniasis, naturally infected with L. infantum. To confirm changes in miR-194 and TRAF6 expression, basal expression of miR-194 and gene expression of TRAF6 was measured using qPCR. PBMCs from healthy dogs and dogs with leishmaniasis were transfected with miR-194 scramble, mimic, and inhibitor and cultured at 37° C, 5% CO2 for 48 hours. The expression of possible targets was measured: iNOS, NO, T-bet, GATA3, and FoxP3 were measured using flow cytometry; the production of cytokines IL-1β, IL-4, IL-6, IL-10, TNF-α, IFN-γ, and TGF-β in cell culture supernatants was measured using capture enzyme-linked immunosorbent assays (ELISA). Parasite load was measured using cytometry and qPCR. Functional assays followed by miR-194 inhibitor and IL-1β blockade and assessment of NO production were also performed. Basal miR-194 expression was increased in PBMC from dogs with Leishmaniasis and was negatively correlated with TRAF6 expression. The mimic of miR-194 promoted an increase in parasite load. There were no significant changes in T-bet, GATA3, or FoxP3 expression with miR-194 enhancement or inhibition. Inhibition of miR-194 increased IL-1β and NO in PBMCs from diseased dogs, and blockade of IL-1β following miR-194 inhibition decreased NO levels. These findings suggest that miR-194 is upregulated in PBMCs from dogs with leishmaniasis and increases parasite load, possibly decreasing NO production via IL-1β. These results increase our understanding of the mechanisms of evasion of the immune response by the parasite and the identification of possible therapeutic targets. Author summary: Visceral leishmaniasis (VL) is a zoonosis in tropical and subtropical regions. In the new world, it is caused by the obligate intracellular protozoan Leishmania infantum. In urban areas, domestic dogs are the primary reservoir. Increase in canine leishmaniasis (CanL) contributes to the increase in VL in humans. One mechanism of parasite survival is through regulation of microRNA (miRNA), responsible for translational control of transcripts related to anti-parasite immunity. One example is miR-194, which is increased in the peripheral blood mononuclear cells (PBMCs) of dogs with leishmaniasis. In the present study, we found that increasing miR-194 increases parasite load, and decreasing miR-194 increases IL1β and NO. Subsequently, we found that the increase in NO depends on IL1β. Since NO its directly involved in parasite load control, these findings contribute to understanding how the parasite evades immune responses and paves the way for the discovery of new therapeutic targets. [ABSTRACT FROM AUTHOR]

The lack of accurate and feasible diagnostic tests poses a significant challenge to visceral leishmaniasis (VL) healthcare services in endemic areas. To date, various VL diagnostic tests have been or are being developed, and their diagnostic performances need to be assessed. In the present study, the diagnostic performances of rk39 RDT, the direct agglutination test (DAT), microscopy, loop-mediated isothermal amplification (LAMP), and miniature direct-on-blood polymerase chain reaction–nucleic acid lateral flow immunoassay (mini-dbPCR-NALFIA) were assessed using quantitative polymerase chain reaction (qPCR) as the reference test in an endemic region of Ethiopia. In this study, 235 suspected VL cases and 104 non-endemic healthy controls (NEHCs) were recruited. Among the suspected VL cases, 144 (61.28%) tested positive with qPCR. The sensitivities for rk39 RDT, DAT, microscopy, LAMP assay, and mini-dbPCR-NALFIA were 88.11%, 96.50%, 76.58%, 94.33%, and 95.80%, respectively. The specificities were 83.33%, 97.96%, 100%, 97.38%, and 98.92% for rk39 RDT, DAT, microscopy, LAMP assay, and mini-dbPCR-NALFIA, respectively. In conclusion, rk39 RDT and microscopy exhibited lower sensitivities, while DAT demonstrated excellent performance. LAMP and mini-dbPCR-NALFIA showed excellent performances with feasibility for implementation in remote endemic areas, although the latter requires further evaluation in such regions. [ABSTRACT FROM AUTHOR]

Background: Leishmaniasis is caused by infection with intracellular protozoans of the genus Leishmania. Transmission occurs predominantly by the bite of phlebotomine sandflies, other routes, including congenital transmission, are rare. The disease manifests as either cutaneous, visceral or mucosal/mucocutaneous leishmaniasis. In recent years, changes in the epidemiological pattern have been reported from Europe. Principal findings: A total of 311 new and 29 published leishmaniasis cases occurring between 01/01/2000 and 12/31/2021 in Austria were collected and analyzed. These encompassed 146 cutaneous (CL), 14 visceral (VL), 4 mucosal, and 3 cases with concurrent VL and CL. In addition, asymptomatic infections, comprising 11 unspecified cases with Leishmania DNA detectable only in the blood and 162 cases with anti-Leishmania antibodies were reported. Particularly since 2016, the incidence of leishmaniasis has steadily risen, mainly attributable to increasing numbers of CL and cases with positive serology against Leishmania species, whereas the incidence of VL has slowly decreased. Analysis revealed that a shift in the causative species spectrum had occurred and that a substantial number of CL cases were caused by members of the Leishmania donovani/infantum complex. Simultaneous occurrence of VL and CL was identified in immunocompromised individuals, but also in a not yet reported case of an immunocompetent child after vertical transmission. Conclusions: The incidence of leishmaniasis has risen in the recent years. The numbers are anticipated to keep rising due to increasing human mobility, including travel and forced migration, growing reservoir host populations as well as expansion and dispersal of vector species caused by climate and habitat changes, urbanization and globalization. Hence, elevated awareness for the disease, including possible transmission in previously non-endemic regions and non-vector transmission modes, support of sandfly surveillance efforts and implementation and establishment of public health interventions in a One Health approach are pivotal in the global efforts to control and reduce leishmaniasis. Author summary: Leishmaniasis is a vector-borne infectious disease caused by intracellular parasites and affects 12–15 million people worldwide. The clinical presentation is variable, and the disease mainly manifests as cutaneous, visceral or mucosal forms. We collected 340 cases of leishmaniasis occurring in Austria over a period of 21 years and performed an analysis of trends to understand the epidemiology of the disease in a non-endemic Central European country. In addition, we report a rare case of concurrent visceral and cutaneous leishmaniasis which was vertically transmitted to an immunocompetent child. Our analyses revealed that the incidences of cutaneous leishmaniasis are rising in Austria and that a shift in the causative species spectrum has occurred. Due to increased population migration, travel activities of humans and animal hosts, growth and spread of the vector populations facilitated primarily by climate changes, a rising number of leishmaniasis cases can be anticipated in many endemic, but intriguingly also in non-endemic regions. The potential expansion of endemicity necessitates raising awareness towards the burden of this disease and provides an incentive to the global health community to continue their efforts in disease control. [ABSTRACT FROM AUTHOR]

Background: Leishmaniasis is mainly prevalent in tropical and subtropical developing countries, where chronic undernutrition often co-exists. Undernutrition is reported to promote the progression of leishmaniasis, but its immune mechanisms have not been fully elucidated. Methods: To simulate chronic undernutrition of patients in epidemic areas and explore the immune mechanism of undernutrition promoting leishmaniasis, BALB/c mouse models with different nutritional imbalances were established, including undernutrition 75%, undernutrition 65% and obesity mouse models. After infection with Leishmania donovani in these model mice, we focused on evaluating the progress of leishmaniasis in the spleen and liver, the expression of important immunosuppressive and immunoactivation molecules, and changes of spleen transcriptome. The immune signaling pathways enriched by differentially expressed genes and hub genes were analyzed. Results: The results showed that among the mouse infection models, undernutrition 75% + infection group had the highest parasite load in the spleen and liver at the 8th week post-infection, possibly due to the continuous increase of PD-1, PD-L1 and TCR. Spleen RNA-seq results suggested that some immune signaling pathways were downregulated in undernutrition 75% + infection group, including neutrophil extracellular trap formation, IL-17 signaling pathway, natural killer cell-mediated cytotoxicity, etc. Among them, neutrophil extracellular trap formation pathway had the largest number of downregulated genes. This also explained why undernutrition 75% + infection group had the highest parasite load. Through PPI network analysis, hub genes such as Lcn2, Ltf, Mpo, Dnaja1, Hspa1a, Hspa1b and Hsph1 were screened out and might play important roles in the process of undernutrition promoting leishmaniasis. Conclusions: Undernutrition upregulated PD-1 and PD-L1 expression and downregulated immune signaling pathways in mice with visceral leishmaniasis. The signaling pathways and hub genes may serve as drug targets or intervention targets for the treatment of leishmaniasis patients with undernutrition. [ABSTRACT FROM AUTHOR]

The parasite Leishmania donovani is one of the species causing visceral leishmaniasis in humans, a deadly infection claiming up to 40,000 lives each year. The current drugs for leishmaniasis treatment have severe drawbacks and there is an urgent need to find new anti-leishmanial compounds. However, the search for drug candidates is complicated by the intracellular lifestyle of Leishmania. Here, we investigate the use of human induced pluripotent stem cell (iPS)-derived macrophages (iMACs) as host cells for L. donovani. iMACs obtained through embryoid body differentiation were infected with L. donovani promastigotes, and high-content imaging techniques were used to optimize the iMACs seeding density and multiplicity of infection, allowing us to reach infection rates up to 70% five days after infection. IC50 values obtained for miltefosine and amphotericin B using the infected iMACs or mouse peritoneal macrophages as host cells were comparable and in agreement with the literature, showing the potential of iMACs as an infection model for drug screening. Author summary: Author summary: Yearly, up two million people in poverty-stricken areas contract leishmaniasis, a disease caused by parasites of the genus Leishmania. When an infected sandfly takes a blood meal, Leishmania parasites enter the host where they are taken up by macrophages. Inside the macrophage, Leishmania parasites establish a niche where they can proliferate. The infection often leads to disability and can result in death. Moreover, the drugs currently available are unsatisfactory due to toxic side effects, high expenses or difficulties in usage. Drug screening assays that are currently used for compound screening often rely on mouse peritoneal macrophages. We have generated human induced pluripotent stem cell derived macrophages and used these as new host cells for Leishmania donovani in the testing of anti-leishmanial compounds. This model has many advantages. For one, it allows us to work with human cells, mimicking the natural infection more closely than murine cells. Secondly, it allows us to obtain bigger batches of uniform cells for screening campaigns. Finally, this approach aligns with the principles of the 3Rs, replacing the use of animals for cultivation of Leishmania and drug screening purposes. [ABSTRACT FROM AUTHOR]

Background: Black disease, also known as visceral leishmaniasis (VL), is a parasitic illness caused by various Leishmania species. The risk of morbidity and mortality increases with delayed diagnosis and treatment. Early VL diagnosis and fast appropriate treatment are critical issues in endemic areas. Methods: This study was a retrospective cross-sectional study to investigate the diagnostic and therapeutic course of patients admitted with the diagnosis of VL in the Children's Medical Center (CMC) Hospital, Tehran, Iran. All cases of VL in patients under the age of 18 hospitalized between the years 2012 to 2022 were enrolled. Results: Twenty-seven patients were enrolled with an average age of 28.13 months with the majority of females (51.8%). Common clinical signs were fever (96.2%) and splenomegaly (92.59%). However, lymphadenopathy was rare. The largest number of patients was from Tehran Province, followed by Ardabil, Khuzestan, Gilan, and Alborz provinces. The most common hematological abnormalities were anemia (85.1%) and thrombocytopenia (44.4%). In accordance with the treatment strategy, liposomal amphotericin B and amphotericin B deoxycholate were given to 11 and 5 patients, respectively. Eleven of them received glucantime. The average length of hospitalization for liposomal amphotericin B was 15.36 ± 12.49 days. In comparison with glucantime (18.38 ±10.26 days) and amphotericin B deoxycholate (20.20± 6.18 days), liposomal amphotericin B group hospitalization was shorter than others were. Conclusion: VL should be included in the differential diagnosis of any child who presents with fever, splenomegaly, and anemia. Concerning the treatment strategy in this study, liposomal amphotericin B had more efficiency and shorter hospitalization duration. [ABSTRACT FROM AUTHOR]

For the past 15 years, trials of combination therapy options for visceral leishmaniasis have been conducted with the aim of identifying effective, and safe treatment regimens that were shorter than existing monotherapy regimens and could also prevent or delay the emergence of drug resistance. Although first-line treatment currently relies on combination therapy in east Africa, this is not true in Latin America owing to disappointing trial results, with lower than expected efficacy seen for the combination treatment group. By contrast, several effective combination therapy regimens have been identified through trials on the Indian subcontinent; yet, first-line therapy is still AmBisome monotherapy as the drug is part of a free donation programme and is highly effective in this region. Achieving a short all-oral combination treatment will require new chemical entities, several of which are currently under evaluation. Future studies should systematically include pharmacological substudies to ensure optimal dosing for all patient groups. To achieve maximal impact of new combination treatments, mechanisms to ensure drug availability and access after trials should be established. Enhancing the longevity of current and novel treatments will require effective systems for early detection of emerging drug resistance. [ABSTRACT FROM AUTHOR]

Background: Leishmania donovani is a protozoan parasite that causes visceral leishmaniasis, a potentially fatal disease in humans and dogs. The epidemiology and transmission dynamics of L. donovani in Sudan are poorly understood. We aim to determine the prevalence and characterization of L. donovani in human hospital cases and domestic dogs using different diagnostic methods in two localities in Gadarif State, Sudan. Methods: A cross-sectional study was conducted from October 2019 to April 2020. Whole blood samples and lymph node aspirates were collected from 69 human and 32 dog participants for parasitological, immunological, and molecular tests. Results: No parasites were detected in blood samples from either humans or dogs. Lymph node microscopy revealed 71.01% positivity in humans and 9.4% in dogs. The IT Leish test showed 82.6% positivity in humans and 43.75% in dogs. PCR confirmed L. donovani infection in all six selected samples (three from humans and three from dogs). Conclusion: The study confirmed the presence of L. donovani in both human and dog populations in the study area, suggesting that dogs may act as reservoirs or hosts for the parasite. The IT Leish kit test was the most sensitive and specific method, while microscopy of blood and lymph node smears was the least sensitive method. Further studies are needed to elucidate the role of dogs in the transmission cycle of L. donovani and the risk factors associated with human infection. [ABSTRACT FROM AUTHOR]