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Cerebral malaria (CM) is a severe complication of Plasmodium falciparum infection that results in thousands of deaths each year, mostly in African children. The in vivo mechanisms underlying this fatal condition are not entirely understood. Using the animal model of experimental cerebral malaria (ECM), we sought mechanistic insights into the pathogenesis of CM. Fatal disease was associated with alterations in tight junction proteins, vascular breakdown in the meninges / parenchyma, edema, and ultimately neuronal cell death in the brainstem, which is consistent with cerebral herniation as a cause of death. At the peak of ECM, we revealed using intravital two-photon microscopy that myelomonocytic cells and parasite-specific CD8+ T cells associated primarily with the luminal surface of CNS blood vessels. Myelomonocytic cells participated in the removal of parasitized red blood cells (pRBCs) from cerebral blood vessels, but were not required for the disease. Interestingly, the majority of disease-inducing parasite-specific CD8+ T cells interacted with the lumen of brain vascular endothelial cells (ECs), where they were observed surveying, dividing, and arresting in a cognate peptide-MHC I dependent manner. These activities were critically dependent on IFN-γ, which was responsible for activating cerebrovascular ECs to upregulate adhesion and antigen-presenting molecules. Importantly, parasite-specific CD8+ T cell interactions with cerebral vessels were impaired in chimeric mice rendered unable to present EC antigens on MHC I, and these mice were in turn resistant to fatal brainstem pathology. Moreover, anti-adhesion molecule (LFA-1 / VLA-4) therapy prevented fatal disease by rapidly displacing luminal CD8+ T cells from cerebrovascular ECs without affecting extravascular T cells. These in vivo data demonstrate that parasite-specific CD8+ T cell-induced fatal vascular breakdown and subsequent neuronal death during ECM is associated with luminal, antigen-dependent interactions with cerebrovasculature.

ABSTRACT Malaria is an infectious disease caused by parasites of several Plasmodium spp. Cerebral malaria (CM) is a common form of severe malaria resulting in nearly 700,000 deaths each year in Africa alone. At present, there is no adjunctive therapy for CM. Although the mechanisms underlying the pathogenesis of CM are incompletely understood, it is likely that both intrinsic features of the parasite and the human host's immune response contribute to disease. The kinase mammalian target of rapamycin (mTOR) is a central regulator of immune responses, and drugs that inhibit the mTOR pathway have been shown to be antiparasitic. In a mouse model of CM, experimental CM (ECM), we show that the mTOR inhibitor rapamycin protects against ECM when administered within the first 4 days of infection. Treatment with rapamycin increased survival, blocked breakdown of the blood-brain barrier and brain hemorrhaging, decreased the influx of both CD4+ and CD8+ T cells into the brain and the accumulation of parasitized red blood cells in the brain. Rapamycin induced marked transcriptional changes in the brains of infected mice, and analysis of transcription profiles predicted that rapamycin blocked leukocyte trafficking to and proliferation in the brain. Remarkably, animals were protected against ECM even though rapamycin treatment significantly increased the inflammatory response induced by infection in both the brain and spleen. These results open a new avenue for the development of highly selective adjunctive therapies for CM by targeting pathways that regulate host and parasite metabolism. IMPORTANCE Malaria is a highly prevalent infectious disease caused by parasites of several Plasmodium spp. Malaria is usually uncomplicated and resolves with time; however, in about 1% of cases, almost exclusively among young children, malaria becomes severe and life threatening, resulting in nearly 700,000 deaths each year in Africa alone. Among the most severe complications of Plasmodium falciparum infection is cerebral malaria with a fatality rate of 15 to 20%, despite treatment with antimalarial drugs. Cerebral malaria takes a second toll on African children, leaving survivors at high risk of debilitating neurological defects. At present, we have no effective adjunctive therapies for cerebral malaria, and developing such therapies would have a large impact on saving young lives in Africa. Here we report results that open a new avenue for the development of highly selective adjunctive therapies for cerebral malaria by targeting pathways that regulate host and parasite metabolism.

Background: Cutaneous leishmaniasis (CL) is a neglected tropical skin disease, caused by the protozoan parasite Leishmania. In Ethiopia, CL is mainly caused by Leishmania aethiopica and can present in different clinical forms. The aim of this study was to assess whether these different forms are associated with differences in parasite genetic and host systemic immune signatures., Methods: Here we analysed the whole genome sequence data for 48 clinical parasite isolates and the systemic immune signature from a cohort of CL patients, who were recruited in Nefas Mewcha, Northern Ethiopia, from January 2019 to January 2022., Results: Our results show that parasites from CL cases with different presentations in a single Ethiopian setting are from the same genetic population based on a permutation test of genome-wide similarity. Furthermore, a logistic regression test for genome wide association did not identify any individual genetic variants significantly associated with disease presentation. We also measured plasma chemokine and cytokine levels of 129 CL patients presenting with different forms of CL. None of the chemokine [eotaxin, eotaxin-3, interleukin (IL)-8, interferon (IFN)-γ-induced protein-10 (IP-10), monocyte chemoattractant protein (MCP)-1, MCP-4, macrophage-derived chemokines (MDC), macrophage inflammatory protein (MIP)-1α, MIP-1β and thymus- and activation-regulated chemokine (TARC)] or cytokine (IFN-γ, IL-1β, interleukin-2, IL-4, IL-6, IL-10, IL-12p70, IL-13, tumor necrosis factor-α) levels measured were significantly different between the different clinical presentations of CL, as measured by Kruskal-Wallis test. We also compared those with healthy nonendemic controls: our results show a chemokine (IP-10, MCP-1, MCP-4, MDC, MIP-1α, MIP-1β and TARC) but not a cytokine immune signature in patients with CL as compared to healthy nonendemic controls, as measured by Mann-Whitney test., Conclusions: The results of our study did not identify a systemic immune signature or parasite genetic factors associated with different clinical presentation of CL., (© 2024. The Author(s).)

Visceral leishmaniasis (VL) is a neglected tropical disease caused by parasites from the Leishmania (L.) donovani complex. VL is characterised by uncontrolled parasite replication in spleen, liver and bone marrow, and by an impaired immune response and high systemic levels of inflammation. Monocytes have been poorly characterised in VL patients. The aim of this study was to evaluate the expression levels of markers involved in the regulation of T cell responses on different subsets of monocytes from the blood of VL patients and healthy non-endemic controls (HNEC). Monocytes can broadly be divided into three subsets: classical, intermediate and non-classical monocytes. Our results show that the percentages of all three subsets stayed similar at the time of VL diagnosis (ToD) and at the end of anti-leishmanial treatment (EoT). We first looked at co-stimulatory receptors: the expression levels of CD40 were significantly increased on classical and intermediate, but not non-classical monocytes, at ToD as compared to EoT and HNEC. CD80 expression levels were also increased on intermediate monocytes at ToD as compared to EoT and HNEC, and on classical monocytes only as compared to HNEC. The levels of CD86 were similar at EoT and ToD and in HNEC on classical and intermediate monocytes, but significantly higher at EoT on non-classical monocytes. We also looked at an inhibitory molecule, PD-L1. Our results show that the expression levels of PD-L1 were significantly higher on all three monocyte subsets at ToD as compared to HNEC, and to EoT on classical and intermediate monocytes. These results show that monocytes from the blood of VL patients upregulate both co-stimulatory and inhibitory receptors and that their expression levels are restored at EoT., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Adem et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Cutaneous leishmaniasis (CL) is a neglected tropical disease caused by Leishmania parasites, that can cause long-term chronic disabilities. The clinical presentation of CL varies in both type and severity. CL presents as three main clinical forms: localised lesions (localised cutaneous leishmaniasis, LCL); mucocutaneous leishmaniasis (MCL) that affects the mucosa of the nose or the mouth; or as disseminated not ulcerating nodules (diffuse cutaneous leishmaniasis, DCL). Here we recruited a cohort of CL patients in a newly established leishmaniasis treatment centre (LTC) in Lay Gayint, Northwest Ethiopia, and collected detailed demographic and clinical data. The results of our study show that more males than females present to the LTC to seek diagnosis and treatment. 70.2% of CL patients presented with LCL and 20.8% with MCL. A small number of patients presented with DCL, recidivans CL (a rare form of CL where new lesions appear on the edges of CL scars) or with a combination of different clinical presentations. The duration of illness varied from 1 month to 180 months. Over a third of CL patients had additional suspected CL cases in their household. Despite the majority of CL patients having heard about CL, only a minority knew about its transmission or that it could be treated. Most CL patients lived in areas where environmental factors known to be associated with the transmission of CL were present. This work highlights that CL is an important public health problem in Lay Gayint and emphasises the urgent need for more CL awareness campaigns, better health education and better disease management practices., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Yizengaw et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Visceral leishmaniasis is a deadly infectious disease and is one of the world's major neglected health problems. Because the symptoms of infection are similar to other endemic diseases, accurate diagnosis is crucial for appropriate treatment. Definitive diagnosis using splenic or bone marrow aspirates is highly invasive, and so, serological assays are preferred, including the direct agglutination test (DAT) or rK39 strip test. These tests, however, are either difficult to perform in the field (DAT) or lack specificity in some endemic regions (rK39), making the development of new tests a research priority. The availability of Leishmania spp. genomes presents an opportunity to identify new diagnostic targets. Here, we use genome data and a mammalian protein expression system to create a panel of 93 proteins consisting of the extracellular ectodomains of the Leishmania donovani cell surface and secreted proteins. We use these panel and sera from murine experimental infection models and natural human and canine infections to identify new candidates for serological diagnosis. We observed a concordance between the most immunoreactive antigens in different host species and transmission settings. The antigen encoded by the LdBPK_323600.1 gene can diagnose Leishmania infections with high sensitivity and specificity in patient cohorts from different endemic regions including Bangladesh and Ethiopia. In longitudinal sampling of treated patients, we observed reductions in immunoreactivity to LdBPK_323600.1 suggesting it could be used to diagnose treatment success. In summary, we have identified new antigens that could contribute to improved serological diagnostic tests to help control the impact of this deadly tropical infectious disease., Importance: Visceral leishmaniasis is fatal if left untreated with patients often displaying mild and non-specific symptoms during the early stages of infection making accurate diagnosis important. Current methods for diagnosis require highly trained medical staff to perform highly invasive biopsies of the liver or bone marrow which pose risks to the patient. Less invasive molecular tests are available but can suffer from regional variations in their ability to accurately diagnose an infection. To identify new diagnostic markers of visceral leishmaniasis, we produced and tested a panel of 93 proteins identified from the genome of the parasite responsible for this disease. We found that the pattern of host antibody reactivity to these proteins was broadly consistent across naturally acquired infections in both human patients and dogs, as well as experimental rodent infections. We identified a new protein called LdBPK_323600.1 that could accurately diagnose visceral leishmaniasis infections in humans., Competing Interests: The authors declare no conflict of interest.

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., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2024 Yimer, Takele, Yizengaw, Nibret, Sumova, Volf, Yismaw, Alehegn, Rowan, Müller, Cotton, Chapman and Kropf.)

Background: Cutaneous leishmaniasis (CL) is a neglected tropical disease that primarily affects the most vulnerable populations. In Ethiopia, where this study took place, CL is an important health problem, however, the incidence of CL is poorly monitored., Objectives: This study took place in a recently established CL treatment centre, at Nefas Mewcha Hospital, Lay Gayint. This area was considered to be endemic for CL, however, no cases of CL from Lay Gayint had previously been officially reported to the Amhara Regional Health Bureau., Methods: Following a CL awareness campaign, a retrospective data review was performed of patients presenting to this centre between July 2019 and March 2021. Basic demographic and clinical data were collected by a nurse and recorded in the logbook of the CL treatment centre., Results: Two hundred and one patients presented for diagnosis and treatment. The age of the patients ranged from 2 to 75 years and 63.2% were males. Most patients were between 10- and 19-years-old. The majority (79.1%) of the patients presented with localised cutaneous leishmaniasis and 20.9% with mucocutaneous leishmaniasis. 98% of the patients tested positive for Leishmania parasites by microscopy., Conclusions: This work underpinned how CL is a major public health problem in the Lay Gayint district. It also shows that raising awareness about CL in the community and providing diagnosis and treatment encouraged patients to travel to seek diagnosis and treatment., Competing Interests: The authors have declared that no conflict of interest exists., (© 2023 The Authors. Skin Health and Disease published by John Wiley & Sons Ltd on behalf of British Association of Dermatologists.)

Visceral leishmaniasis (VL) and HIV co-infection (VL/HIV) has emerged as a significant public health problem in Ethiopia, with up to 30% of patients with VL co-infected with HIV. These patients suffer from recurrent VL relapses and increased mortality. Those with a previous history of VL relapses (recurrent VL/HIV) experience increased VL relapses as compared to patients with HIV presenting with their first episode of VL (primary VL/HIV). Our aim was to identify drivers that account for the higher rate of VL relapses in patients with recurrent VL/HIV (n = 28) as compared to primary VL/HIV (n = 21). Our results show that the relapse-free survival in patients with recurrent VL/HIV was shorter, that they had higher parasite load, lower weight gain, and lower recovery of all blood cell lineages. Their poorer prognosis was characterized by lower production of IFN-gamma, lower CD4 + T cell counts, and higher expression of programmed cell death protein 1 (PD1) on T cells., Competing Interests: The authors have declared that no conflict of interest exists., (© 2023 The Authors.)

Visceral leishmaniasis (VL) patients co-infected with HIV (VL/HIV patients) experience frequent treatment failures, VL relapses, opportunistic infections, and higher mortality. Their immune system remains profoundly suppressed after clinical cure and they maintain higher parasite load. This is in contrast with patients with VL alone (VL patients). Since neutrophils play a critical role in the control of Leishmania replication and the regulation of immune responses, we tested the hypothesis that neutrophil activation status and effector functions are fully restored in VL, but not in VL/HIV patients. Our results show the neutrophil counts and all activation markers and effector functions tested in our study were reduced at the time of diagnosis in VL and VL/HIV patients as compared to controls. CD62L, CD63, arginase 1 expression levels and reactive oxygen species production were restored at the end of treatment in both groups. However, neutrophil counts, CD10 expression and phagocytosis remained significantly lower throughout follow-up in VL/HIV patients; suggesting that dysregulated neutrophils contribute to the impaired host defence against pathogens in VL/HIV patients., Competing Interests: The authors have declared that no competing interests exist.

Visceral leishmaniasis (VL) is a neglected tropical disease that causes substantial morbidity and mortality and is a growing health problem in Ethiopia, where this study took place. Most individuals infected with Leishmania donovani parasites will stay asymptomatic, but some develop VL that, if left untreated, is almost always fatal. This stage of the disease is associated with a profound immunosuppression, characterised by impaired production of Interferonγ (IFNγ), a cytokine that plays a key role in the control of Leishmania parasites, and high expression levels of an inhibitory receptor, programmed cell death 1 (PD1) on CD4+ T cells. Here, we tested the contribution of the interaction between the immune checkpoint PD1 and its ligand PDL-1 on the impaired production of IFNγ in VL patients. Our results show that in the blood of VL patients, not only CD4+, but also CD8+ T cells express high levels of PD1 at the time of VL diagnosis. Next, we identified PDL-1 expression on different monocyte subsets and neutrophils and show that PDL-1 levels were significantly increased in VL patients. PD1/PDL-1 inhibition resulted in significantly increased production of IFNγ, suggesting that therapy using immune checkpoint inhibitors might improve disease control in these patients., Competing Interests: The authors have declared that no competing interests exist.

Visceral leishmaniasis (VL) has emerged as a clinically important opportunistic infection in HIV patients, as VL/HIV co-infected patients suffer from frequent VL relapse. Here, we follow cohorts of VL patients with or without HIV in Ethiopia. By the end of the study, 78.1% of VL/HIV-but none of the VL patients-experience VL relapse. Despite a clinically defined cure, VL/HIV patients maintain higher parasite loads, lower BMI, hepatosplenomegaly, and pancytopenia. We identify three immunological markers associated with VL relapse in VL/HIV patients: (1) failure to restore antigen-specific production of IFN-γ, (2) persistently lower CD4 + T cell counts, and (3) higher expression of PD1 on CD4 + and CD8 + T cells. We show that these three markers, which can be measured in primary hospital settings in Ethiopia, combine well in predicting VL relapse. The use of our prediction model has the potential to improve disease management and patient care., Competing Interests: The authors declare no competing interests., (© 2021 The Authors.)

Visceral leishmaniasis (VL) is a fatal disease and a growing public health problem in East Africa, where Ethiopia has one of the highest VL burdens. The largest focus of VL in Ethiopia is driven by high prevalence in migrant agricultural workers and associated with a high rate of coinfection with HIV. This coinfection makes VL more difficult to treat successfully and is associated with a high rate of relapse, with VL/HIV patients frequently experiencing many relapses of VL before succumbing to this infection. We present genome-wide data on Leishmania donovani isolates from a longitudinal study of cohorts of VL and VL/HIV patients reporting to a single clinic in Ethiopia. Extensive clinical data allow us to investigate the influence of coinfection and relapse on the populations of parasites infecting these patients. We find that the same parasite population is responsible for both VL and VL/HIV infections and that, in most cases, disease relapse is caused by recrudescence of the population of parasites that caused primary VL. Complex, multiclonal infections are present in both primary and relapse cases, but the infrapopulation of parasites within a patient loses genetic diversity between primary disease presentation and subsequent relapses, presumably due to a population bottleneck induced by treatment. These data suggest that VL/HIV relapses are not caused by genetically distinct parasite infections or by reinfection. Treatment of VL does not lead to sterile cure, and in VL/HIV, the infecting parasites are able to reestablish after clinically successful treatment, leading to repeated relapse of VL. IMPORTANCE Visceral leishmaniasis (VL) is the second largest cause of deaths due to parasite infections and a growing problem in East Africa. In Ethiopia, it is particularly associated with migrant workers moving from regions of nonendemicity for seasonal agricultural work and is frequently found as a coinfection with HIV, which leads to frequent VL relapse following treatment. Insight into the process of relapse in these patients is thus key to controlling the VL epidemic in Ethiopia. We show that there is little genetic differentiation between the parasites infecting HIV-positive and HIV-negative VL patients. Moreover, we provide evidence that relapses are caused by the initially infecting parasite population and that treatment induces a loss of genetic diversity in this population. We propose that restoring functioning immunity and improving antiparasitic treatment may be key in breaking the cycle of relapsing VL in VL/HIV patients.

Diagnosis of visceral leishmaniasis (VL) and assessment of treatment response in human immunodeficiency virus (HIV)-coinfected patients still relies on invasive tissue aspiration. This hampers scale-up and decentralization of care in resource-limited settings. Noninvasive diagnostics are urgently needed. KATEX is a frequently used latex agglutination test for Leishmania antigen in urine that has never been evaluated in HIV-coinfected individuals from Leishmania donovani -endemic areas. This was an exploratory sub-study embedded within the screening phase of a trial in highly endemic northwestern Ethiopia. All patients were HIV-positive and aspirate-confirmed VL cases. We assessed diagnostic accuracy of KATEX for VL diagnosis and as test of cure at end of treatment, using tissue aspirate parasite load as reference methods. We also described the evolution of weekly antigen levels during treatment. Most of the 87 included patients were male (84, 97%), young (median age 31 years), and had poor immune status (median cluster of differentiation type 4 count 56 cells/μL). KATEX had moderate sensitivity (84%) for VL diagnosis. KATEX had moderate sensitivity (82%) and a moderate negative predictive value (87%) but only low specificity (49%) and a low positive predictive value (40%) for the assessment of treatment outcomes. Weekly antigen levels showed characteristic patterns during treatment of patients with different initial parasite loads and treatment outcomes. Antigen detection in urine using KATEX can contribute to improved VL diagnosis in HIV-coinfected patients but has limited use for monitoring of treatment response. Better noninvasive diagnostics are needed to reduce reliance on invasive methods and thus to expand and improve clinical care for VL in resource-limited settings.

Background: Biomarkers predicting the risk of VL treatment failure and relapse in VL/HIV coinfected patients are needed. Nested within a two-site clinical trial in Ethiopia (2011-2015), we conducted an exploratory study to assess whether (1) levels of Leishmania antigenuria measured at VL diagnosis were associated with initial treatment failure and (2) levels of Leishmania antigenuria at the end of treatment (parasitologically-confirmed cure) were associated with subsequent relapse. Methods: Leishmania antigenuria at VL diagnosis and cure was determined using KAtex urine antigen test and graded as negative (0), weak/moderate (grade 1+/2+) or strongly-positive (3+). Logistic regression and Kaplan-Meier methods were used to assess the association between antigenuria and (1) initial treatment failure, and (2) relapse over the 12 months after cure, respectively. Results: The analysis to predict initial treatment failure included sixty-three coinfected adults [median age: 30 years interquartile range (IQR) 27-35], median CD4 count: 56 cells/μL (IQR 38-113). KAtex results at VL diagnosis were negative in 11 (17%), weak/moderate in 17 (27%) and strongly-positive in 35 (36%). Twenty (32%) patients had parasitologically-confirmed treatment failure, with a risk of failure of 9% (1/11) with KAtex-negative results, 0% (0/17) for KAtex 1+/2+ and 54% (19/35) for KAtex 3+ results. Compared to KAtex-negative patients, KAtex 3+ patients were at increased risk of treatment failure [odds ratio 11.9 (95% CI 1.4-103.0); P : 0.025]. Forty-four patients were included in the analysis to predict relapse [median age: 31 years (IQR 28-35), median CD4 count: 116 cells/μL (IQR 95-181)]. When achieving VL cure, KAtex results were negative in 19 (43%), weak/moderate (1+/2+) in 10 (23%), and strongly positive (3+) in 15 patients (34%). Over the subsequent 12 months, eight out of 44 patients (18%) relapsed. The predicted 1-year relapse risk was 6% for KAtex-negative results, 14% for KAtex 1+/2+ and 42% for KAtex 3+ results [hazard ratio of 2.2 (95% CI 0.1-34.9) for KAtex 1+/2+ and 9.8 (95% CI 1.8-82.1) for KAtex 3+, compared to KAtex negative patients; P : 0.03]. Conclusion: A simple field-deployable Leishmania urine antigen test can be used for risk stratification of initial treatment failure and VL relapse in HIV-patients. A dipstick-format would facilitate field implementation.

Visceral leishmaniasis (VL) is a neglected tropical disease that affects the poorest communities and can cause substantial morbidity and mortality. Visceral leishmaniasis is characterized by the presence of Leishmania parasites in the spleen, liver and bone marrow, hepatosplenomegaly, pancytopenia, prolonged fever, systemic inflammation and low body mass index (BMI). The factors impacting on the severity of VL are poorly characterized. Here we performed a cross-sectional study to assess whether co-infection of VL patients with intestinal parasites influences disease severity, assessed with clinical and haematological data, inflammation, cytokine profiles and BMI. Data from VL patients was similar to VL patients co-infected with intestinal parasites, suggesting that co-infection of VL patients with intestinal parasites does not alter disease severity.

Visceral leishmaniasis (VL) is a fatal parasitic disease. Unfortunately, diagnosis of VL in east Africa currently relies on aspiration of tissue from the spleen or bone marrow, which is painful and potentially dangerous. We sought to determine whether peripheral blood could be used instead of invasive tissue aspirates to diagnose VL, using three parasite concentration techniques. Three hundred and one consecutive people suspected of having VL were recruited. Compared with microscopy of tissue aspirates, the diagnostic accuracy of peripheral blood microscopy was as follows: whole blood thin smear sensitivity 1.5% (95% confidence interval [CI] 0.0-8.3) and specificity 100% (95% CI 76.8-100); buffy-coat smear sensitivity 19.5% (95% CI 14.3-25.6) and specificity 98.9% (95% CI 94.1-100); peripheral blood mononuclear cell (PBMC) smear sensitivity 33.7% (95% CI 27.3-40.5) and specificity 95.7% (95% CI 89.6-98.6). Sensitivity of PBMC smears was significantly higher in human immunodeficiency virus (HIV)-coinfected patients (N = 48/301); two-sample test of proportions, P = 0.0097; sensitivity 55.9% (95% CI 37.9-72.8) and specificity 92.9% (95% CI 66.1-99.8), and correlated with the degree of parasite load in the tissue. Combining the results from smears of both PBMC and buffy coat yielded a sensitivity and specificity of 67.6% (95% CI 49.1-82.6) and 92.9% (95% CI 66.1-99.8), respectively, in HIV-coinfected patients. In this setting, VL could be ruled-in with peripheral blood microscopy in a substantial number of VL suspects and may reduce the number of tissue aspirations performed, particularly in HIV-coinfected patients. More sensitive and logistically feasible methods than light microscopy are needed to detect Leishmania donovani parasites present in blood., (© The American Society of Tropical Medicine and Hygiene.)

Background: Despite high prevalence of visceral leishmaniasis and malaria in the study area, their coinfection remains unknown. Therefore, this study was aimed to document VL-malaria coinfections and their associated factors., Methods: A cross-sectional study was conducted among clinical suspected VL patients attending Metema hospital, Northwest Ethiopia, from January 2014 to June 2014. Blood sample was tested by rk39 antigen-based DiaMed IT-Leish dipstick and Giemsa stain microscopic examination of thick and thin blood smears for malaria detection was performed., Result: A total of 384 VL suspected patients were included in the study. Out of these, the prevalence of VL was 83 (21.6%) while the prevalence of malaria was 45 (11.7%). Of malaria cases, 40 (89%) were positive for P. falciparum and 5 (11%) positive for P. vivax . The overall prevalence of VL-malaria coinfection was 16 (4.2%). One-hundred eighty (46.9%) study participants have history of travel. Of these, 10 (5.6%) have VL-malaria coinfections. Age less than 5 years was associated with VL-malaria coinfection., Conclusion: This study highlights the importance of performing malaria screening amongst VL patients living in malaria-endemic areas, particularly in patients under five years.

Immunologically, active visceral leishmaniasis (VL) is characterized by profound immunosuppression, severe systemic inflammatory responses, and an impaired capacity to control parasite replication. Neutrophils are highly versatile cells, which play a crucial role in the induction as well as the resolution of inflammation, the control of pathogen replication, and the regulation of immune responses. Neutrophil functions have been investigated in human cutaneous leishmaniasis; however, their role in human VL is poorly understood. In the present study we evaluated the activation status and effector functions of neutrophils in patients with active VL and after successful anti-leishmanial treatment. Our results show that neutrophils are highly activated and have degranulated; high levels of arginase, myeloperoxidase, and elastase, all contained in neutrophils' granules, were found in the plasma of VL patients. In addition, we show that a large proportion of these cells are immature. We also analyzed effector functions of neutrophils that are essential for pathogen clearance and show that neutrophils have an impaired capacity to release neutrophil extracellular traps, produce reactive oxygen species, and phagocytose bacterial particles, but not Leishmania parasites. Our results suggest that impaired effector functions, increased activation, and immaturity of neutrophils play a key role in the pathogenesis of VL.

Malnutrition is commonly associated with increased infectious disease susceptibility and severity. Whereas malnutrition might enhance the incidence of disease as well as its severity, active infection can in turn exacerbate malnutrition. Therefore, in a malnourished individual suffering from a severe infection, it is not possible to determine the contribution of the pre-existing malnutrition and/or the infection itself to increased disease severity. In the current study we focussed on two groups of malnourished, but otherwise healthy individuals: moderately malnourished (BMI: 18.4-16.5) and severely malnourished (BMI <16.5) and compared several immune parameters with those of individuals with a normal BMI (≥18.5). Our results show a similar haematological profile in all three groups, as well as a similar ratio of CD4+ and CD8+ T cells. We found significant correlations between low BMI and increased levels of T helper (Th) 1 (Interferon (IFN)-γ, (interleukin (IL)-2, IL-12), Th2 (IL-4, IL-5, IL-13), as well as IL-10, IL-33 and tumor necrosis factor-α, but not IL-8 or C reactive protein. The activities of arginase, an enzyme associated with immunosuppression, were similar in plasma, peripheral blood mononuclear cells (PBMC) and neutrophils from all groups and no differences in the expression levels of CD3ζ, a marker of T cell activation, were observed in CD4+ and CD8+T cells. Furthermore, whereas the capacity of neutrophils from the malnourished groups to phagocytose particles was not impaired, their capacity to produce reactive oxygen species was impaired. Finally we evaluated the frequency of a subpopulation of low-density neutrophils and show that they are significantly increased in the malnourished individuals. These differences were more pronounced in the severely malnourished group. In summary, our results show that even in the absence of apparent infections, healthy malnourished individuals display dysfunctional immune responses that might contribute to increased susceptibility and severity to infectious diseases., Competing Interests: The authors have declared that no competing interests exist.

One of the key immunological characteristics of active visceral leishmaniasis (VL) is a profound immunosuppression and impaired production of Interferon-γ (IFN-γ). However, recent studies from Bihar in India showed using a whole blood assay, that whole blood cells have maintained the capacity to produce IFN-γ. Here we tested the hypothesis that a population of low-density granulocytes (LDG) might contribute to T cell responses hyporesponsiveness via the release of arginase. Our results show that this population is affected by the anticoagulant used to collect blood: the frequency of LDGs is significantly lower when the blood is collected with heparin as compared to EDTA; however, the anticoagulant does not impact on the levels of arginase released. Next, we assessed the capacity of whole blood cells from patients with active VL to produce IFN-γ and IL-10 in response to antigen-specific and polyclonal activation. Our results show that whole blood cells produce low or levels below detection limit of IFN-γ and IL-10, however, after successful treatment of VL patients, these cells gradually regain their capacity to produce IFN-γ, but not IL-10, in response to activation. These results suggest that in contrast to VL patients from Bihar, India, whole blood cells from VL patients from Gondar, Ethiopia, have lost their ability to produce IFN-γ during active VL and that active disease is not associated with sustained levels of IL-10 production following stimulation.

Background: Diagnostic guidelines for Visceral Leishmaniasis (VL) in the East African region are complex. Patients meeting the VL clinical case definition should be tested by rK39 rapid diagnostic test (RDT) followed by the Direct Agglutination Test (DAT) or tissue aspiration if RDT-negative. Otherwise, RDT-positive patients should be started on VL treatment. We evaluated how this guideline is adhered to by assessing the routine clinical practice in a university hospital in North-West Ethiopia., Methods: Retrospective record analysis was done for all patients who had an rK39-RDT done at University of Gondar (UoG) Hospital between June 2012 and June 2013. We described the diagnostic work-up performed and the proportion initiated on VL treatment by test result., Results/findings: From a total of 928 patients tested, 308 (33.2%) were rK39 RDT-positive. Spleen or bone marrow aspiration was done for 237 (77.2%) RDT-positive patients. Of these, 165 were confirmed parasitologically, yielding a positive predictive value of 69.6%. Only 126 (20.3%) of the 620 patients with a negative rK39 test underwent further testing by tissue aspiration, of which 22 (17.5%) were also parasitology positive. HIV test results were available for 570 (61.4%) patients and 36 (6.3%) were HIV-infected. Of the 187 parasitologically confirmed patients, 182 (97.3%) were started on VL treatment., Conclusions/discussion: A negative rK39 test was often not followed by further testing and a positive rK39 test result was followed by tissue aspiration in three out of four cases. Further research is required to understand why the diagnostic work-up did not comply with the guidelines, including evaluating adherence to the VL clinical case definition and quality of rK39-RDT testing.

Objective: After the epidemics of L. donovani complex in 2004/05 in human patients, to investigate the presence of antibodies against L. donovani in domestic animals in north-west Ethiopia., Methods: Two hundred and three domestic animals were screened. Serum and biopsy samples were collected. A modified direct agglutination test (DAT) for canine reservoirs was used to screen serum samples at ≥ 1:320 cut-off titre. Giemsa stain and culture on Novy macNeal Nicolae (NNN) media were used for biopsy samples. Pre-tested questionnaires were used to elicit information on potential risk factors., Results: Antibody against L. donovani in domestic animals was detected in 30.5% of animals. The highest seropositivity rates were 41.9% in cattle, 40% in dogs, 33.3% in donkeys, 10% in goats and 4.8% in sheep. No Leishmania parasite was isolated from spleen, liver, skin snip and exudates, bone marrow or lymph node of dogs. Dogs owned by households with history of kala-azar treatment and humans sharing the house with cattle were more affected by visceral leishmaniasis (P < 0.05)., Conclusion: This study showed a high serological prevalence of leishmaniasis in domestic animals. Their role in the epidemiology of visceral leishmaniasis remains unclear., (© 2014 John Wiley & Sons Ltd.)

Objective: To assess the prevalence and risk factors of smear positive pulmonary tuberculosis among Gondar town prisoners, North West Ethiopia., Methods: A cross sectional study was conducted from February to July, 2008 in Gondar Prison. Prisoners with cough duration of more than two weeks were involved in the study by giving three sputum samples and filling the questionnaires prepared for risk factor assessment. Acid fast staining technique was employed to detect the presence of the Mycobacterium tuberculosis bacilli in the sputum samples. Data was analyzed using SPSS version13 computer software and presented in table. Chi-square test was used to assess associations and a P-value less than 0.05 was taken as significant., Results: A total of 384 prisoners, 349 male and 35 females, with a mean age of 33.3 years were involved in the study. The prevalence of smear positive pulmonary tuberculosis among those prisoners with cough duration of more than two weeks was 8.59%. Only the length of imprisonment had a significant association (χ (2)= 18.82, P-value<0.0001) with the prevalence of tuberculosis., Conclusions: This study indicated that tuberculosis among prisoners with cough duration of more than two weeks in Gondar prison is very high. Therefore Periodic screening of the prisoners and screening of newly introduced prisoners should be practiced so as to minimize the burden of tuberculosis in prisoners., (Copyright © 2015 Hainan Medical College. Production and hosting by Elsevier B.V. All rights reserved.)

The development of rK39-based rapid diagnostic tests (RDTs) has greatly aided the diagnosis of visceral leishmaniasis, especially in the Indian subcontinent and Brazil, by offering high sensitivity and specificity. However, these tests have been less sensitive and less specific in sub-Saharan Africa. To improve upon the performance of rK39 in Africa, we engineered the fusion molecule rK28, which retained some of the rK39 repeats and combined them with repeat sequences from two additional Leishmania genes. This polyprotein was used in the development of several prototype RDTs by different commercial manufacturers with the goal of assessing relative performance in inexpensive formats. Here, we report field studies showing that the rK28 antigen could be readily adapted to a variety of RDT formats to achieve high sensitivity, generally > 90%, and adequate specificity to aid in the diagnosis of human visceral leishmaniasis in East Africa, Asia, and South America., (© The American Society of Tropical Medicine and Hygiene.)

Background: Visceral leishmaniasis (VL) causes considerable morbidity and mortality in Ethiopia. Data on the prevalence and associated risk factors on malnutrition among VL patients in Ethiopia are scarce. This study aimed to assess the prevalence of malnutrition and its associated risk factor among VL patients in Northwest Ethiopia., Methods: An institution-based cross-sectional study was conducted from June to September 2012 at four leishmaniasis treatment sites in Northwest Ethiopia. Four hundred and three adult VL patients were enrolled in the study. Malnutrition was defined as a body mass index (BMI) ≤ 18.5 kg/m2. The data collected from the VL patients included sex, age, residence, occupation, weight, height, laboratory results (HIV, hemoglobin, intestinal parasites). Multivariate logistic regression model was used to determine the strength of association between malnutrition and associated risk factors., Results: Among 403 adult VL patients 385 (95.5%) were malnourished. Twenty eight percent (n = 113), 30.3% (n = 122), and 37.2% (n = 150) were mildly, moderately and severely malnourished, respectively. The prevalence of intestinal parasitic infection was 47.6% (n = 192) and it was associated with malnutrition (P = 0.01). The prevalence of VL-HIV co-infection was 10.4% (n = 42). Hook worm, Giardia intestinalis and Ascaris lumbircoides were the leading prevalent intestinal parasites. Factors such as age, sex, residence, occupation, HIV status and anemia were not associated with severe malnutrition., Conclusions: The prevalence of malnutrition in VL patients was very high and it was associated with intestinal parasitic infections. Therefore, screening of severely malnourished VL patients for intestinal parasitic infections during admission is recommended.

Background: Visceral leishmaniasis (VL) is a systemic disease caused by the Leishmania donovani complex. It is one of the fatal diseases if left untreated. In Ethiopia, there are many VL endemic foci. The aim of this study was to determine the trends of VL in the study area., Methodology: A retrospective study was conducted at Addis Zemen health center from September 2005 to August 2011. Data were collected from laboratory registration book and entered and analyzed by using SPSS version 20 software and P value of ≤0.05 was considered statistically significant., Result: A total of 7161 VL suspected cases were reported in the study area. The overall prevalence of VL was 2801 (39.1%). Of the 2801 VL positive cases, the highest annual prevalence, 988 (46.8%), was reported in 2005 but the trend gradually decreases. Majority of the VL confirmed cases were in the age groups of 5-14 years and males were more affected., Conclusion: The prevalence of VL in the study area was high in early 2005 but, gradually, the trend has been decreased and it becomes one of VL endemic foci in Ethiopia.

Background and Objectives: Visceral leishmaniasis (VL) is one of the neglected diseases affecting the poorest segment of world populations. Sepsis is one of the predictors for death of patients with VL. This study aimed to assess the prevalence and factors associated with bacterial sepsis, causative agents, and their antimicrobial susceptibility patterns among patients with VL., Methods: A cross-sectional study was conducted among parasitologically confirmed VL patients suspected of sepsis admitted to the University of Gondar Hospital, Northwest Ethiopia, from February 2012 to May 2012. Blood cultures and other clinical samples were collected and cultured following the standard procedures., Results: Among 83 sepsis suspected VL patients 16 (19.3%) had culture confirmed bacterial sepsis. The most frequently isolated organism was Staphylococcus aureus (68.8%; 11/16), including two methicillin-resistant isolates (MRSA). Patients with focal bacterial infection were more likely to have bacterial sepsis (P < 0.001)., Conclusions: The prevalence of culture confirmed bacterial sepsis was high, predominantly due to S. aureus. Concurrent focal bacterial infection was associated with bacterial sepsis, suggesting that focal infections could serve as sources for bacterial sepsis among VL patients. Careful clinical evaluation for focal infections and prompt initiation of empiric antibiotic treatment appears warranted in VL patients.

Bacteremia due to Shigella is rare. A 26-year-old HIV-negative male presented with a persistent high-grade fever of two months duration to the Leishmaniasis Research and Treatment Center of University of Gondar Hospital. He was anorexic and had lost significant weight (from 76 to 57 kg in 4 months, BMI = 17.2 kg/m(2)). He also complained of headache, chills, and rigor. In the last one year, he was experiencing a few episodes of acute bloody diarrhea, the last episode being two months ago. Microscopy from splenic aspiration showed Leishman-Donovan bodies with parasite load of +3. The blood culture showed Shigella species, but the stool was culture negative. The isolate was sensitive to most tested antibiotic discs, sulfamethoxazole, ceftriaxone, gentamicin, tetracycline, and norfloxacilin, except ampicillin. Therefore, requesting blood culture for identifying unexpected type of organisms causing infections in patients with underlying diseases like visceral leishmaniasis should be encouraged.

Background/objectives: Visceral leishmaniasis (VL) caused by Leishmania donovani is a major health problem in Ethiopia. Parasites in disparate regions are transmitted by different vectors, and cluster in distinctive genotypes. Recently isolated strains from VL and HIV-VL co-infected patients in north and south Ethiopia were characterized as part of a longitudinal study on VL transmission., Methodology/principal Findings: Sixty-three L. donovani strains were examined by polymerase chain reaction (PCR) targeting three regions: internal transcribed spacer 1 (ITS1), cysteine protease B (cpb), and HASPB (k26). ITS1- and cpb--PCR identified these strains as L. donovani. Interestingly, the k26--PCR amplicon size varied depending on the patient's geographic origin. Most strains from northwestern Ethiopia (36/40) produced a 290 bp product with a minority (4/40) giving a 410 bp amplicon. All of the latter strains were isolated from patients with HIV-VL co-infections, while the former group contained both VL and HIV-VL co-infected patients. Almost all the strains (20/23) from southwestern Ethiopia produced a 450 bp amplicon with smaller products (290 or 360 bp) only observed for three strains. Sudanese strains produced amplicons identical (290 bp) to those found in northwestern Ethiopia; while Kenyan strains gave larger PCR products (500 and 650 bp). High-resolution melt (HRM) analysis distinguished the different PCR products. Sequence analysis showed that the k26 repeat region in L. donovani is comprised of polymorphic 13 and 14 amino acid motifs. The 13 amino acid peptide motifs, prevalent in L. donovani, are rare in L. infantum. The number and order of the repeats in L. donovani varies between geographic regions., Conclusions/significance: HASPB repeat region (k26) shows considerable polymorphism among L. donovani strains from different regions in East Africa. This should be taken into account when designing diagnostic assays and vaccines based on this antigen.

Background: Visceral leishmaniasis is a parasitic disease associated with high mortality. The most important foci of visceral leishmaniasis in Ethiopia are in the Northwest and are predominantly associated with high rates of HIV co-infection. Co-infection of visceral leishmaniasis patients with HIV results in higher mortality, treatment failure and relapse. We have previously shown that arginase, an enzyme associated with immunosuppression, was increased in patients with visceral leishmaniasis and in HIV seropositive patients; further our results showed that high arginase activity is a marker of disease severity. Here, we tested the hypothesis that increased arginase activities associated with visceral leishmaniasis and HIV infections synergize in patients co-infected with both pathogens., Methodology/principal Findings: We recruited a cohort of patients with visceral leishmaniasis and a cohort of patients with visceral leishmaniasis and HIV infection from Gondar, Northwest Ethiopia, and recorded and compared their clinical data. Further, we measured the levels of arginase activity in the blood of these patients and identified the phenotype of arginase-expressing cells. Our results show that CD4(+) T cell counts were significantly lower and the parasite load in the spleen was significantly higher in co-infected patients. Moreover, our results demonstrate that arginase activity was significantly higher in peripheral blood mononuclear cells and plasma of co-infected patients. Finally, we identified the cells-expressing arginase in the PBMCs as low-density granulocytes., Conclusion: Our results suggest that increased arginase might contribute to the poor disease outcome characteristic of patients with visceral leishmaniasis and HIV co-infection.

The underlying mechanisms resulting in the profound immune suppression characteristic of human visceral leishmaniasis (VL) are not fully understood. Here, we tested the hypothesis that arginase, an enzyme associated with immunosuppression, is higher in patients with VL and contributes to impaired T cell responses. We recruited patients with VL before and after treatment and healthy controls and measured the arginase metabolism in the blood of these individuals. Our results show that arginase activity is significantly higher in the blood of patients with active VL as compared to controls. These high levels of arginase decline considerably once the patients are successfully treated. We identified the phenotype of arginase-expressing cells among PBMCs as neutrophils and show that their frequency was increased in PBMCs of patients before treatment; this coincides with reduced levels of L-arginine in the plasma and decreased expression levels of CD3ζ in T cells.