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Scrub typhus is an acute illness caused by the bacteria Orientia tsutsugamushi and is transmitted by mites. Scrub typhus propagates via infected chigger bites (larval stage). Diagnosing scrub typhus is challenging due to its ability to mimic symptoms of other febrile illnesses. Conventional methods such as Weil‐Felix, ELISA, and PCR are available for diagnosing scrub typhus. The Weil‐Felix test was formerly used in developing nations to diagnose scrub typhus, but it is not recommended since it lacks both specificity and sensitivity. IFA and ELISA are superior for detecting scrub typhus; however, they are not as effective at detecting the illness in its early stages and require convalescent sampling to confirm positive samples. However, because the Orientia tsutsugamushi serotypes differ in their genetic makeup, PCR‐based approaches have become less applicable despite their higher specificity and sensitivity. Nanomaterial‐based biosensing could help detect scrub typhus early due to its high surface area, electrical conductance, and chemical stability. This study emphasizes the need for point‐of‐care detection of this under‐diagnosed but fatal disease, emphasizing the importance of nanobiosensors in early diagnosis. The pathophysiology of scrub typhus, standard diagnostic procedures, and the critical role that nanobiosensors play in the early detection of scrub typhus are discussed. [ABSTRACT FROM AUTHOR]

Spotted fever group (SFG) rickettsia, the causative agent of SFG rickettsiosis, is predominantly carried by ticks, whereas Orientia tsutusgamushi, the causative agent of scrub typhus, is primarily transmitted by chigger mites in Japan. In this study, we attempted to isolate intracellular eubacteria from Leptotrombidium scutellare, a major vector of O. tsutsugamushi; moreover, we isolated an SFG rickettsia using a mosquito‐derived cell line. Draft genome sequences of this unique isolate, by applying criteria for species delimitation, classified this isolate as a novel strain, proposed as "Rickettsia kedanie." Further genetic analysis identified conserved virulence factors, and the isolate successfully propagated in mammalian cells, suggesting its ability to cause diseases in humans. The presence of SFG rickettsia in unfed larvae implies potential dual‐pathogen carriage and reflects a symbiotic relationship similar to that between the mites and O. tsutsugamushi, indicating possibility of its transovarial transmission from female adults. Furthermore, conserved genomic similarity of the novel isolate to known SFG rickettsia suggests potential multiple hosts, including chiggers and ticks. In the natural environment, ticks, chigger mites, and wild animals may carry new isolates, complicating the infection cycle and increasing the transmission risks to humans. This discovery challenges the conventional association of SFG rickettsia with ticks, emphasizing its implications for research and disease control. However, this study was confined to a particular species of chigger mites and geographic area, underscoring the necessity for additional studies to comprehend the ecological dynamics, host interactions, and health implications linked to this newly identified SFG rickettsia. [ABSTRACT FROM AUTHOR]

Acute encephalitis syndrome (AES) is a major public health concern in India as the aetiology remains unknown in the majority of cases with the current testing algorithm. We aimed to study the incidence of Japanese encephalitis (JE) and determine the aetiology of non‐JE AES cases to develop an evidence‐based testing algorithm. Cerebrospinal fluid (CSF) samples were tested for Japanese encephalitis virus by ELISA and polymerase chain reaction (PCR). Multiplex real‐time PCR was done for Dengue, Chikungunya, West Nile, Zika, Enterovirus, Epstein Barr Virus, Herpes Simplex Virus, Adenovirus, Cytomegalovirus, Herpesvirus 6, Parechovirus, Parvovirus B19, Varicella Zoster Virus, Scrub typhus, Rickettsia species, Leptospira, Salmonella species, Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, Plasmodium species and by ELISA for Mumps and Measles virus. Of the 3173 CSF samples, 461 (14.5%) were positive for JE. Of the 334 non‐JE AES cases, 66.2% viz. Scrub typhus (25.7%), Mumps (19.5%), Measles (4.2%), Parvovirus B19 (3.9%) Plasmodium (2.7%), HSV 1 and 2 (2.4%), EBV and Streptococcus pneumoniae (2.1% each), Salmonella and HHV 6 (1.2% each) were predominant. Hence, an improved surveillance system and our suggested expanded testing algorithm can improve the diagnosis of potentially treatable infectious agents of AES in India. [ABSTRACT FROM AUTHOR]

Background Globally, India has a high zoonotic disease burden and lacks surveillance data in humans and animals. Rodents are known reservoirs for many zoonotic diseases and their synanthropic behavior poses a great public health threat. Methods In this study, trapped rodents/shrews from randomly selected villages within Puducherry, India, and their ectoparasites were screened for zoonotic pathogens, namely, Orientia tsutsugamushi , other pathogenic rickettsiae, Leptospira spp. Cryptosporidium spp. Coxiella burnetii and methicillin-resistant Staphylococcus aureus (MRSA) using conventional PCR. A total of 58 rodents/shrews were trapped from 11 villages. The species trapped were Suncus murinus (49/58, 84.48%), Rattus rattus (8/58, 13.79%) and Rattus norvegicus (1/58, 1.72%). All ectoparasites collected were identified as mites and its infestation rate was 46.55% (27/58). Results Real-time PCR targeting the 47 kDa gene of O. tsutsugamushi revealed positivity in one rodent and one shrew (3.45%) and two mite pools (7.41%). Conventional PCR targeting the 56 kDa gene revealed positivity in one shrew and two mite pools and the phylogenetic analysis of all three amplicons indicated the circulation of the Gilliam-related serotype. MRSA was detected in the alimentary tract of a shrew (1/32, 3.13%). Leptospira spp. Rickettsia, Cryptosporidium spp. and Co. burnetii tested negative. Conclusions The detection of zoonotic pathogens within reservoir hosts and vectors poses a risk of transmission to humans. This study signifies the need for zoonotic pathogen surveillance in synanthropic rodents/shrews. [ABSTRACT FROM AUTHOR]

Objectives: Scrub typhus is the most common rickettsial disease in India, caused by Orientia tsutsugamushi and transmitted by chigger mites. Previously prevalent in South India, a resurgence of scrub typhus cases has recently affected Eastern India. This study aimed to estimate the prevalence and describe the clinicolaboratory profile of scrub typhus in paediatric patients (1-12 years old) living in Eastern India. Methods: This prospective observational study was conducted from January to December 2019 at the Dr B C Roy Post Graduate Institute of Paediatric Sciences, Kolkata, India. All acute undifferentiated cases of febrile illness, in patients aged between 1-12 years, were tested using scrub typhus serology by ELISA. Demographic details, clinical features, laboratory findings, complications and treatment outcomes of these scrub typhus patients were extracted and analysed. Results: Out of 1,473 patients with acute febrile illness, 67 (4.5%) children were diagnosed with scrub typhus. The mean age of the selected patients was 5.22 ± 3.05 years, and the majority (64.2%) had been running a fever since the preceding 7-14 days. Gastrointestinal symptoms such as vomiting (43.3%) and abdominal pain (32.8%) were most frequently observed. Major clinical signs of scrub typhus were hepatomegaly (41.8%) and splenomegaly (31.3%). Complications were observed in 74.6% of patients, with thrombocytopenia (40.3%) and meningoencephalitis (29.9%) occurring more frequently. The case fatality rate of the study sample was 1.5%. Conclusion: Classical eschar was absent in three-fourth of the studied patients. Hence, this study advocates laboratory scrub typhus tests for all suspected cases in the endemic region (Eastern India). Prompt treatment with doxycycline and/or azithromycin could prevent complications such as thrombocytopenia/meningoencephalitis and reduce mortality. [ABSTRACT FROM AUTHOR]

Background: Scrub typhus, caused by Orientia tsutsugamushi, rarely leads to central nervous system involvement. Although intracerebral bleeding is rare due to endemicity and a significant proportion of underdiagnoses, it should be considered a noteworthy differential diagnosis in endemic regions in patients with relevant history and clinical findings. Case presentation: We present the case of a 40-year-old Nepali woman who visited the emergency department with complaints of left-sided weakness for 6 hours and an acute febrile illness with an eschar for 7 days and was diagnosed with scrub typhus by immunoglobulin M enzyme-linked immunosorbent assay of the serum. Imaging revealed a right-sided frontotemporal hematoma, and further examination revealed pulmonary edema with multiple organ dysfunction syndrome. The patient was mechanically ventilated and was treated with antibiotics, steroids, vasopressors, and antipyretics. However, the hematoma was treated conservatively, with ongoing neurological recovery at the 6-month follow-up. Conclusion: Although neurological complications and intracranial hemorrhage are uncommon, physicians must be cautious when making differential diagnoses and initiating appropriate therapies to avoid serious or fatal complications. [ABSTRACT FROM AUTHOR]

Background: Fever is a symptom, not a disease. It is the non-specific manifestation of several underlying illnesses. Aims and Objectives: The aims and objectives of this study were to determine the serological profile of patients with febrile illnesses, to study their different unusual presentations, and to study patients with coinfections with more than one type of disease. Materials and Methods: Blood samples from 15,000 febrile patients were collected during the study period of 6 months. Different serological tests were performed in our laboratory based on clinical suspicion and in a few patients, more than one type of tests were done. The unusual presentations of different diseases were studied. Results: Various percentages of male and female patients were seen suffering from different types of febrile illnesses. The different positive results out of total tests done for respective diseases were dengue (848/7708), vivax malaria (64/800), falciparum malaria (4/800), leptospirosis (95/798), scrub typhus (77/2433), enteric fever (75/1506), hepatitis B (143/9368), hepatitis C (11/9368), human immunodeficiency virus (HIV) (37/10900), systemic lupus erythematosus (5/158), acute renal failure (66/158), and syphilis (54/583). Different unusual presentations among patients with several diseases were noted, along with their percentages of occurrence. Coinfections among dengue and enteric fever (3%), mixed infection with Plasmodium vivax and Plasmodium falciparum (0.25%), scrub typhus and Leptospira (15.6%), hepatitis B and hepatitis C (0.649%), hepatitis B and HIV (5%), hepatitis C and HIV (8.33%), and syphilis and HIV (27.68%). Conclusion: Dengue fever was found to be the most common of all febrile illnesses. The different unusual presentations of those diseases should suggest an improved clinical suspicion and better diagnostic stewardship. Coinfection was most commonly seen among syphilis and HIV and these data must suggest to always looking for associated illnesses in a patient with a single diagnosis. [ABSTRACT FROM AUTHOR]

Background: Acute undifferentiated fever (AUF) remains a significant reason for hospitalization among children, particularly in Southeast Asia. Common causative agents include dengue, scrub typhus, murine typhus, leptospirosis, and enteric fever. This study aims to delineate the clinical and etiological profiles of AUF in children. Materials and Methods: A prospective observational study was conducted over one year in the Department of Pediatrics at a tertiary care hospital in Central India. The study enrolled children with fever lasting less than 21 days and without a specific focus of infection identified through history, physical examination, and routine investigations. Results: Among the 90 children included in the study, the most prevalent cause of undifferentiated fever was typhoid fever (31.1%), followed by malaria (21.1%), dengue fever (18.9%), and urinary tract infections (10%). Other notable causes included acute gastroenteritis (8.9%), pneumonia (5.6%), bronchiolitis (2.2%), hepatitis (1.1%), and pharyngotonsillitis (1.1%). Common clinical symptoms observed were pyrexia (100%), headache (65.6%), rash (47.8%), and abdominal pain (31.1%). Laboratory findings indicated mild anemia in the majority of cases, leukopenia in cases of dengue and malaria, and thrombocytopenia in dengue cases. Conclusion: Non-malarial infections are predominant causes of AUF in children within this region of Central India. Scrub typhus, dengue, and enteric fever were identified as significant contributors. The study underscores the necessity for improved diagnostic facilities to reduce the proportion of undiagnosed fevers, often assumed to be viral in nature. [ABSTRACT FROM AUTHOR]

This study evaluated the use of F-18 fluorodeoxyglucose (FDG) PET/CT imaging to differentiate between scrub typhus and systemic lupus erythematosus (SLE) in patients presenting with lymphadenopathy. We carried out a retrospective analysis of 18 scrub typhus patients and seven SLE patients, using various imaging parameters, including lymph node size, spleen and liver lengths, the distance between the two farthest lesions (Dmax), and assessments of glucose metabolism. On FDG PET images, we measured the maximum standardized uptake value (SUVmax) of the lymph nodes, spleen, and liver and the mean standardized uptake value (SUVmean) of the liver and spleen. The Dmax values of scrub typhus patients were significantly longer than those of SLE patients, indicating that lymphadenopathy is more generalized in the patients with scrub typhus. The SUVmax values for the lymph node, spleen, and liver were also higher in patients with scrub typhus, while the SUVmean of the liver and spleen did not differ between the two groups. This study is the first to compare FDG PET/CT images between these two conditions, suggesting the potential of this imaging modality to provide critical diagnostic distinctions. [ABSTRACT FROM AUTHOR]

Simple Summary: Leptotrombidium imphalum (a chigger species) can serve as a transmitting vector of scrub typhus. Based on the field investigation in southwest China from 2001 to 2022, this article presents the first report on the distribution and infestation of L. imphalum on small mammals in the region. A total of 2161 L. imphalum were identified from 218 small mammal hosts that crossed three orders, and the majority of the mites were found on the order Rodentia (rodents). Different host species had different susceptibility to the infestation of L. imphalum, and the shrew gymnure (Neotetracus sinensis) was much more susceptible to the infestation than other host species. Leptotrombidium imphalum exhibited an aggregated distribution among different individuals of its hosts. The positive correlation between the infestation indices for L. imphalum on small mammals and the occurrence of scrub typhus, together with the low host specificity of the mite, indicates the potential risk of the mite. Leptotrombidium imphalum is a species of chigger mites, and it can serve as a transmitting vector of scrub typhus. Southwest China is an important focus of scrub typhus. Based on the field investigation in southwest China from 2001 to 2022, this article presents the first report on the distribution and infestation of L. imphalum on rodents and other sympatric small mammals in the region. A total of 2161 L. imphalum were identified from 218 small mammal hosts in 21 of 114 survey sites. The 17 host species of L. imphalum crossed 13 genera and 5 families in 3 orders (Rodentia, Eulipotyphla, and Scandentia), indicating the low host specificity of the mite. The Asian house rat (Rattus tanezumi) was the dominant host species in the 21 sites where L. imphalum were collected, and 49.38% of mites were found on R. tanezumi. Different small mammals had different susceptibility to the infestation of L. imphalum. The prevalence (PM = 27.66%), infestation mean abundance (MA = 6 mites/per examined host), and mean intensity (MI = 21.69 mites/per infested host) for L. imphalum on the shrew gymnure (Neotetracus sinensis) were much higher than those on other host species (p < 0.05), indicating N. sinensis had a high susceptibility to the infestation of L. imphalum. The infestation indices for L. imphalum on small mammal hosts varied along different altitude and latitude gradients (p < 0.05), indicating the environmental heterogeneity of the mite infestation. Leptotrombidium imphalum exhibited an aggregated distribution among different individuals of its hosts. Besides the low host specificity of L. imphalum, the prevalence of the mite was positively correlated with the occurrence of scrub typhus, indicating the potential risk of the mite. [ABSTRACT FROM AUTHOR]

Background: Febrile illnesses that persist despite initial treatment are common clinical challenges in (sub)tropical low-resource settings. Our aim is to review infectious etiologies of "prolonged fevers" (persistent febrile illnesses, PFI) and to quantify relative contributions of selected neglected target diseases with limited diagnostic options, often overlooked, causing inadequate antibiotic prescriptions, or requiring prolonged and potentially toxic treatments. Methods: We performed a systematic review of articles addressing the infectious etiologies of PFI in adults and children in sub-/tropical low- and middle-income countries (LMICs) using the PRISMA guidelines. A list of target diseases, including neglected parasites and zoonotic bacteria (e.g., Leishmania and Brucella), were identified by infectious diseases and tropical medicine specialists and prioritized in the search. Malaria and tuberculosis (TB) were not included as target diseases due to well-established epidemiology and diagnostic options. Four co-investigators independently extracted data from the identified articles while assessing for risk of bias. Results: 196 articles from 52 countries were included, 117 from Africa (33 countries), 71 from Asia (16 countries), and 8 from Central and -South America (3 countries). Target diseases were reported as the cause of PFI in almost half of the articles, most frequently rickettsioses (including scrub typhus), relapsing fever borreliosis (RF-borreliosis), brucellosis, enteric fever, leptospirosis, Q fever and leishmaniasis. Among those, RF-borreliosis was by far the most frequently reported disease in Africa, particularly in Eastern Africa. Rickettsioses (including scrub typhus) were often described in both Africa and Asia. Leishmaniasis, toxoplasmosis and amoebiasis were the most frequent parasitic etiologies. Non-target diseases and non-tropical organisms (Streptococcus pneumoniae, Escherichia coli, and non-typhoidal Salmonella spp) were documented in a fifth of articles. Conclusions: Clinicians faced with PFI in sub-/tropical LMICs should consider a wide differential diagnosis including enteric fever and zoonotic bacterial diseases (e.g., rickettsiosis, RF-borreliosis and brucellosis), or parasite infections (e.g., leishmaniasis) depending on geography and syndromes. In the absence of adequate diagnostic capacity, a trial of antibiotics targeting relevant intra-cellular bacteria, such as doxycycline or azithromycin, may be considered. Author summary: "Prolonged" or "Persistent" Febrile illnesses (PFI) are common challenging diagnostic entities in LMICs. Symptoms and signs can be non-specific and diagnostic tests are often not available, and antibiotics inadequate. This systematic review aimed to investigate important causes of PFI in different geographical regions, as well as to highlight lack of data in these areas to stimulate discussion for future research. We found that zoonotic bacterial and neglected parasitic diseases accounted for substantial proportions of PFI cases, in particular rickettsiosis, borreliosis, brucellosis, leptospirosis, melioidosis, leishmaniasis, toxoplasmosis and amoebiasis. Although data is very limited for many regions, our results suggest that the geographical context can help inform clinicians on the likelihood of different infections in a patient with PFI. [ABSTRACT FROM AUTHOR]

Objective: Defining whether a suspected case was due to scrub typhus through laboratory testing, to understand the prevalence of scrub typhus in Shijiazhuang City, Hebei Province. Methods: An epidemiological investigation was conducted on the suspected case, utilizing Weil-Felix test and indirect immunofluorescence assay (IFA) to detect specific antibodies against O. tsutsugamushi in serum specimens. Additionally, PCR amplification of the 56-kDa and groEL genes was performed, followed by constructing a phylogenetic tree to identify the genotype. Results: The acute phase titer of the Weil-Felix test for the case was 1:160, which increased to 1:320 in the recovery phase. IFA assay revealed IgG titers against O. tsutsugamushi of 1:64 in the acute phase and 1:256 in the recovery phase. Sequence alignment of the PCR amplified fragment showed the highest similarity with the O. tsutsugamushi genotype. Kawasaki sequence, ranging from 99.71 to 100.00%. The strain exhibited the closest genetic relationship with the known O. tsutsugamushi Kawasaki genotype. Conclusion: This study confirms the presence of O. tsutsugamushi in Shijiazhuang City, Hebei Province, with the identified strain belonging to the Kawasaki genotype, marking the first diagnosis of this strain in the region. [ABSTRACT FROM AUTHOR]

Key Clinical Message: In this case report, we describe the successful management of severe scrub typhus with pneumonia, sepsis, and multiple organ dysfunction in a pregnant woman. Despite initial challenges, the patient responded favorably to fecal microbiota transplantation and oral fecal microbiota capsule therapy. Scrub typhus, caused by Orientia tsutsugamushi, can lead to severe multiorgan dysfunction and carries a mortality rate of up to 70% if not treated properly. In this report, we present the case of a 27‐year‐old pregnant woman at 18 + 6 weeks gestation whose symptoms worsened 15 days after onset and progressed to severe pneumonia with sepsis and multiple organ dysfunction syndrome. After the pathogen was confirmed by next‐generation sequencing analysis of bronchoalveolar‐lavage fluid and blood samples, the patient's treatment was switched to antiinfective chloramphenicol. The patient also underwent uterine evacuation due to a miscarriage. Extracorporeal membrane oxygenation was discontinued once the pulmonary infection significantly improved. Subsequently, the patient had recurrent diarrhea, abdominal distension, and difficulty eating. The antibiotic regimen was adjusted according to the drug sensitivity, but the diarrhea and abdominal distension still did not improve. Following a comprehensive multidisciplinary risk assessment, we initiated fecal microbiota transplantation and oral fecal microbiota capsule therapy. As a result, the patient's condition was effectively managed, and they were gradually discharged. Fecal microbiota transplantation may be a safe and effective treatment for severe pneumonia and shock in pregnant women. This has significant implications for maternal health. However, further clinical cases are required to observe its long‐term effectiveness. [ABSTRACT FROM AUTHOR]

Scrub typhus is one of the most underdiagnosed and unreported febrile illnesses caused by an obligate intracellular bacterium named Orientia tsutsugamushi and the antibiotics were the commonly prescribed drugs to treat the condition. Due to the widespread development of antimicrobial resistance to the standard drugs, the new therapeutic approach is warranted. The drug repurposing approach plays a novel concept in identifying alternative therapies to fight against pathogens. To investigate the anti-scrub typhus activity of nine newly FDA-approved antibiotics from 2018-2019 against Orientia tsutsugamushi deubiquitylase (OtDUB) compared with standard drugs. The structure of ligands was retrieved from the PubChem database and the crystal structure of target OtDUB (PDB ID: 6UPU) with a resolution of 2.2 Ao was retrieved from the Protein data bank. Molecular docking studies were performed using PyRx version 0.8 and the amino acid interactions were visualized using BIOVIA Discovery studio and the pharmacokinetic properties of the drugs were analysed by SWISS ADME software. The binding affinity of the drugs to deubiquitylase and amino acids was determined using the In silico approach, the drug Omadacycline shows superior activity when compared with other drugs. Based on our preliminary in-silico docking studies, we conclude that Omadacycline may be repurposed for the treatment of scrub typhus as it shows a higher binding affinity of -8.6 kcal/mol when compared to the standard drugs. For the further advancement of the study, in vitro and in vivo studies should be performed. [ABSTRACT FROM AUTHOR]

Background: Acute hepatitis due to various tropical infections can mimic the clinical picture of acute viral hepatitis(AVH), leading to increased morbidity and mortality. We aimed to identify clinical and laboratory parameters that could help to distinguish acute hepatitis due to tropical infections from AVH. Methods: We retrospectively analyzed our database of 150 children (107 boys) with AVH and 50 children(34 boys)with acute hepatitis due to tropical infections between January 2013 and March 2023. Clinical features, investigations, complications and outcomes were compared. Results: Hepatitis A (75%) was the commonest etiology of AVH while enteric fever (34%), dengue (26%), scrub typhus (20%) and leptospirosis (16%) constituted the majority of tropical infections. Persistent fever and skin rashes were found in 88% and 16% of patients respectively in the tropical infection group and none in the AVH group (p < 0.001). On univariate analysis, prodromal symptoms, clinically detectable jaundice, cholestatic pattern, total and direct bilirubin and liver enzymes were significantly higher in AVH while headache, myalgia, leukopoenia, thrombocytopenia, hyponatremia were significantly higher in tropical infections group (all p < 0.05). Multivariate analysis identified thrombocytopenia (Odds ratio [OR] 4.237) as an independent positive predictive factor and markedly elevated total bilirubin (OR 0.575), direct bilirubin (OR 0.498), aspartate aminotransferase (OR 0.841) and alanine aminotransferase (OR 0.863) as independent negative predictive factors for acute hepatitis due to tropical infections. Conclusion: High index of suspicion for tropical infections is warranted in patients with persistent fever after the onset of jaundice, especially in the presence of skin rash and thrombocytopenia. [ABSTRACT FROM AUTHOR]

Tsutsugamushi disease was first described in China by Hong Ge in 313. In his book Zhouhou Beiji Fang, three escharassociated febrile diseases were described: Shashidu, Zhongxidu, and Shegongdu. Shashidu was identified as being identical to tsutsugamushi disease in Japan: it occurred in riverside areas, exhibited an eschar, and was transmitted by tiny red “sand lice”. The nature of Zhongxidu remains unknown, but we propose that it is another type of Orientia tsutsugamushi infection: it occurred in mountainous areas, an eschar was observed, and the causative vector was not identified. Moreover, Zhongxidu would have predated Shashidu by five centuries; thus, the first documentation of tsutsugamushi disease would date back 2.2 millennia. O. tsutsugamushi infection without eschar has not been identified in ancient Chinese literature and may be included in Shanghan. Several ancient Chinese books describe that Shegongdu occurs following a Shegong bite. Shegong is described as a bug resembling a cockroach or cicada with a crossbow-like structure, possibly the hypostome and unfolded palps of tick, in its mouth. Thus, Shegong refers to an engorged tick and Shegongdu is a tick-borne rickettsiosis. However, due to a lack of entomological knowledge, these findings have not been recognized for the past 1.7 millennia. [ABSTRACT FROM AUTHOR]

Scrub typhus is an acute febrile disease due to Orientia tsutsugamushi (Ot) infection and can be life-threatening with organ failure, hemorrhage, and fatality. Yet, little is known as to how the host reacts to Ot bacteria at early stages of infection; no reports have addressed the functional roles of type I versus type II interferon (IFN) responses in scrub typhus. In this study, we used comprehensive intradermal (i.d.) inoculation models and two clinically predominant Ot strains (Karp and Gilliam) to uncover early immune events. Karp infection induced sequential expression of Ifnb and Ifng in inflamed skin and draining lymph nodes at days 1 and 3 post-infection. Using double Ifnar1-/-Ifngr1-/- and Stat1-/- mice, we found that deficiency in IFN/STAT1 signaling resulted in lethal infection with profound pathology and skin eschar lesions, which resembled to human scrub typhus. Further analyses demonstrated that deficiency in IFN-γ, but not IFN-I, resulted in impaired NK cell and macrophage activation and uncontrolled bacterial growth and dissemination, leading to metabolic dysregulation, excessive inflammatory cell infiltration, and exacerbated tissue damage. NK cells were found to be the major cellular source of innate IFN-γ, contributing to the initial Ot control in the draining lymph nodes. In vitro studies with dendritic cell cultures revealed a superior antibacterial effect offered by IFN-γ than IFN-β. Comparative in vivo studies with Karp- and Gilliam-infection revealed a crucial role of IFN-γ signaling in protection against progression of eschar lesions and Ot infection lethality. Additionally, our i.d. mouse models of lethal infection with eschar lesions are promising tools for immunological study and vaccine development for scrub typhus. Author summary: Scrub typhus can lead to severe complications and even fatality if not treated properly; however, the early host immune responses to Ot bacterium infection remain unclear. This study focused on the functional roles of IFNs in i.d. inoculation mouse models of scrub typhus. We found that mice lacking IFN receptors were highly susceptible to Ot infection, which resulted in severe pathology and skin eschar lesions that resembled to human scrub typhus. Further investigation revealed that the lack of IFN-γ, but not IFN-I, resulted in dysregulated innate immune responses, leading to uncontrolled bacterial burdens and tissue damage. Using IFN-γ reporter mice and neutralizing antibody treatment, we confirmed that NK cells were the major source of early IFN-γ, and thus contributed to the bacterial control in the draining lymph nodes. Moreover, our comparative studies with two Ot strains revealed bacterium strain- and dose-dependent eschar formation and disease severity. In conclusion, our study highlights the crucial role of IFN-γ signaling in ensuring host protection against Ot infection. Our mouse models resemble skin eschar lesions and lethal infections observed in human disease, offering potential for future immunological studies on scrub typhus. [ABSTRACT FROM AUTHOR]

Objective: Acute encephalitis syndrome (AES) in children results in significant neurocognitive deficits or mortality. It is pertinent to study the AES patterns periodically to identify the changes in the etiological trends and outcomes. Our objective was to find the etiological agents of AES, mode of diagnosis, treatment given, and outcomes. Methods: We reviewed the electronic records of children aged 1 month to 15 years who were admitted with AES in our centre from January 2015 to December 2019. We analyzed the the clinical, laboratory, and radiological profile of these children and adolescents in relation to their outcome. Poor outcome was defined as death, discharge against medical advice with neurological deficits, or Glasgow Outcome Score Extended (GOS-E) d≤ 5 at the time of discharge. Results: Among 250 patients admitted with AES during the study period, a definitive etiological diagnosis was established in 56.4% of children (30.4% viral, 22% bacterial). Scrub typhus (11.2%) and dengue (9%) were the two most common underlying illnesses. Serology helped in clinching the diagnosis in 30% of children. A surge in AES cases in the post-monsoon season was observed in our cohort. Third-generation cephalosporin drugs (85.7%) and acyclovir (77.7%) were the most commonly used empiric antimicrobial drugs. About one-third of children (n = 80) had a poor outcome. GCS ≤ 8 at presentation and requirement for invasive ventilation were found to be significant predictors of poor outcome. Conclusion: A definitive diagnosis was obtained in about half of the children with AES. Viral (30.4%) and rickettsial infections (22%) were the common etiologies identified. Poor outcome was observed in 32 % of patients. [ABSTRACT FROM AUTHOR]

Background: Scrub typhus is a mite-borne zoonotic disease caused by Orientia tsutsugamushi and commonly presents with fever, rash, and eschar. Systemic complications develop later in the illness including, meningoencephalitis, pericardial effusion, myocarditis, and pneumonitis. In this article, we will be presenting different neurological manifestations of scrub typhus along with functional outcomes studied at a tertiary care center in New Delhi. Methods: This ambispective observational study was conducted at Army Hospital Research and Referral, New Delhi, during January 2018-January 2020. Febrile illness, serologically confirmed as scrub typhus and developing neurological complications were included. A predesigned clinical proforma was recorded for demographics, clinical features, neurological examination, supported with laboratory and/or radiology evaluation, and functional outcomes using the modified Rankin Scale (mRS). Results: In our cohort of 7 patients' majority were male (71%) with mean age at presentation being 42.5 years. Eschar was present in only 2 cases (28%) and a syndromic clinical diagnosis of meningoencephalitis was made in 3 (43%), acute flaccid quadriparesis in 2 (28%); and symptomatic seizure and parkinsonism in 1 patient each (14%). CSF showed lymphocytic pleocytosis with protein elevation in 57% cases. Systemic dysfunction was noted in the form of thrombocytopenia (57%), hyponatremia (42%), elevated transaminases (57%). Symptoms resolved with Doxycycline ± Rifampicin therapy in all cases, with good functional outcomes in majority of (89%) cases. Conclusion: Neurological complications in scrub typhus have a wide spectrum involving meninges, encephalon, basal ganglia, cranial, and peripheral nerves. High index of suspicion with early serological testing (ELISA) is a must in undifferentiated fevers. Timely initiation of appropriate therapy leads to good clinical outcomes, in majority of cases with neurological involvement. [ABSTRACT FROM AUTHOR]

Background and Objectives: Scrub typhus (ST) is detected in one-fourth of patients with acute febrile illnesses, confirming its nationwide re-emergence. The disease, if not diagnosed, can lead to multiple organ dysfunction and mortality. Being a vector-borne zoonotic disease, the molecular survey for pathogens in animal hosts is essential to predict the risk of its transmission to humans. Hence, this study aimed at identifying the effective animal tissue and molecular technique for zoonotic surveillance of ST infection in small animal hosts. Methods: Rodents/shrews were trapped from seventeen randomly selected villages in Puducherry between July and September, 2022. The presence of Orientia tsutsugamushi in ectoparasites and tissues including blood, lung, liver, spleen, kidney, heart, brain, and intestine retrieved from the animals was screened by nested PCR targeting 56 kDa, real-time PCR (qPCR) targeting 47 kDa and traD, and conventional PCR targeting groEL. The Weil–Felix test was carried out to detect antibodies against O. tsutsugamushi in rodent/shrew serum samples. Diagnostic accuracy measures of the molecular tests were calculated for each of the tissues by latent class modeling. Results:O. tsutsugamushi detected in the rodents/shrews were identified to be Karp-like and Kawasaki-like strains. Upon statistical analysis, qPCR targeting 47 kDa exhibited the highest accuracy measures in most of the tissues analyzed, with perfect sensitivity and specificity of 100% and 97% for intestine and lung samples for the epidemiological surveillance, respectively. Interpretation and Conclusion: The study recommends qPCR targeting 47 kDa gene and analysis of intestine and lung along with blood for the zoonotic surveillance of ST infection. [ABSTRACT FROM AUTHOR]

Background Scrub typhus (ST) is endemic in Fukushima, with the largest number of cases reported in Japan from 2009 to 2010. Although ST is highly treatable, its atypical clinical presentation impedes diagnosis, causing delays in treatment. Methods We review the clinical features of ST in adults from 2008 to 2017 at Ohta Nishinouchi General Hospital in Fukushima, Japan. Results Fifty-five cases (serotype Karp 24, Irie/Kawasaki 21, Hirano/Kuroki 10) of ST were confirmed via serology based on elevated immunoglobulin (Ig)M and IgG and polymerase chain reaction positivity of eschar samples. The mean age was 69 years, and 64% were female. The case fatality rate was 1.8% (1/55). Approximately 70% of cases (38/55) were not diagnosed as ST upon the initial clinic visit. Inappropriate use of antibiotics was identified in 22% of cases (12/55). In terms of atypical clinical features, 1 or more of the manifestations, fever, rash, and eschar, was absent in 31% of cases (17/55). Approximately 11% of cases presented without eschar (6/55; Karp 1, Irie/Kawasaki 1, Hirano/Kuroki 4). Moreover, severe complications were observed with shock and disseminated intravascular coagulation in 7% of cases (4/55), Thus, while 53% of cases presented with the typical triad (29/55), unusual complications and atypical features occurred in 40% (22/55). Conclusions Diagnosis of ST becomes clinically challenging in the absence of typical features. In Fukushima, an endemic area of ST, an atypical presentation involving multisystem disease is common. [ABSTRACT FROM AUTHOR]

Acute encephalitis syndrome (AES) in children poses a significant public health challenge in India. This study aims to explore the utility of host inflammatory mediators and neurofilament (NfL) levels in distinguishing etiologies, assessing disease severity, and predicting outcomes in AES. We assessed 12 mediators in serum (n = 58) and 11 in cerebrospinal fluid (CSF) (n = 42) from 62 children with AES due to scrub typhus, viral etiologies, and COVID‐associated multisystem inflammatory syndrome (MIS‐C) in Southern India. Additionally, NfL levels in serum (n = 20) and CSF (n = 18) were examined. Clinical data, including Glasgow coma scale (GCS) and Liverpool outcome scores, were recorded. Examining serum and CSF markers in the three AES etiology groups revealed notable distinctions, with scrub typhus differing significantly from viral and MIS‐C causes. Viral causes had elevated serum CCL11 and CCL2 compared with scrub typhus, while MIS‐C cases showed higher HGF levels than scrub typhus. However, CSF analysis showed a distinct pattern with the scrub typhus group exhibiting elevated levels of IL‐1RA, IL‐1β, and TNF compared with MIS‐C, and lower CCL2 levels compared with the viral group. Modeling the characteristic features, we identified that age ≥3 years with serum CCL11 < 180 pg/mL effectively distinguished scrub typhus from other AES causes. Elevated serum CCL11, HGF, and IL‐6:IL‐10 ratio were associated with poor outcomes (p = 0.038, 0.005, 0.02). Positive CSF and serum NfL correlation, and negative GCS and serum NfL correlation were observed. Median NfL levels were higher in children with abnormal admission GCS and poor outcomes. Measuring immune mediators and brain injury markers in AES provides valuable diagnostic insights, with the potential to facilitate rapid diagnosis and prognosis. The correlation between CSF and serum NfL, along with distinctive serum cytokine profiles across various etiologies, indicates the adequacy of blood samples alone for assessment and monitoring. The association of elevated levels of CCL11, HGF, and an increased IL‐6:IL‐10 ratio with adverse outcomes suggests promising avenues for therapeutic exploration, warranting further investigation. [ABSTRACT FROM AUTHOR]

Background: The existing literature lacks studies examining the epidemiological link between scrub typhus and deep vein thrombosis (DVT) or pulmonary embolism (PE), and the long-term outcomes. The objective of this study is to explore the potential association between scrub typhus and the subsequent risk of venous thromboembolism, and long-term mortality. Method: This nationwide cohort study identified 10,121 patients who were newly diagnosed with scrub typhus. Patients with a prior DVT or PE diagnosis before the scrub typhus infection were excluded. A comparison cohort of 101,210 patients was established from the general population using a propensity score matching technique. The cumulative survival HRs for the two cohorts were calculated by the Cox proportional hazards model. Result: After adjusting for sex, age, and comorbidities, the scrub typhus group had an adjusted HR (95% CI) of 1.02 (0.80–1.30) for DVT, 1.11 (0.63–1.93) for PE, and 1.16 (1.08–1.25) for mortality compared to the control group. The post hoc subgroup analysis revealed that individuals younger than 55 years with a prior scrub typhus infection had a significantly higher risk of DVT (HR: 1.59; 95% CI: 1.12–2.25) and long-term mortality (HR: 1.75; 95% CI, 1.54–1.99). Conclusion: The scrub typhus patients showed a 16% higher risk of long-term mortality. For those in scrub typhus cohort below 55 years of age, the risk of developing DVT was 1.59 times higher, and the risk of mortality was 1.75 times higher. Age acted as an effect modifier influencing the relationship between scrub typhus and risk of new-onset DVT and death. [ABSTRACT FROM AUTHOR]

Background Scrub typhus is an understudied vector-borne bacterial infection. Methods We tested archived fever samples for scrub typhus seropositivity to begin charting its geographic distribution in Indonesia. We analysed 1033 serum samples from three sites. IgM and IgG enzyme-linked immunosorbent assay (ELISA) against Orientia tsutsugamushi was performed using Karp, Kato, Gilliam, TA 716 antigens. To determine the cutoff in the absence of a presumed unexposed population and gold standard tests, we identified the visual inflection point, performed change point analysis, and used finite mixture models. Results The optical density cutoff values used for IgM and IgG were 0.49 and 0.13, respectively. Across all sites, IgM seropositivity was 4.6% (95% CI: 3.4 to 6.0%) while IgG seropositivity was 4.4% (95% CI: 3.3 to 5.8%). The overall seropositivity across sites was 8.8% (95% CI: 8.1 to 11.7%). The overall seropositivity for Jambi, Denpasar, Tabanan were 9.7% (95% CI: 7.0 to 13.3%), 8.0% (95% CI: 5.7 to 11.0%), 9.0% (95% CI: 6.1 to 13.0%), respectively. Conclusions We conclude that O. tsutsugamushi exposure in humans occurred at all sites analysed and could be the cause of illness in some cases. Though it was not the main cause of acute fever in these locations, it is still important to consider scrub typhus in cases not responding to beta-lactam antibiotics. Future seroprevalence surveys and testing for scrub typhus in acute febrile illness studies will be essential to understand its distribution and burden in Indonesia. [ABSTRACT FROM AUTHOR]

Background: Scrub typhus is an acute infectious disease caused by Orientia tsutsugamushi. Guillain–Barre syndrome (GBS) is an autoimmune-mediated peripheral neuropathy with a frequent history of prodromal infections, but GBS associated with scrub typhus is very rare. Case presentation: We report a 51-year-old male patient who developed dysarthria and peripheral facial paralysis following the cure of scfrub typhus. CSF examination and electrophysiological findings suggested a diagnosis of GBS. After treatment with intravenous immunoglobulin, the patient's neurological condition improved rapidly. Conclusions: Scrub typhus infection is likely to be a potential predisposing factor in GBS, while scrub typhus-associated GBS has a favorable prognosis. [ABSTRACT FROM AUTHOR]

The number of people suffering from scrub typhus, which is not of concern, is increasing year by year, especially in Yunnan Province, China. From June 1, 2021 to August 15, 2022, a total of 505 mammalian samples were collected from farm, forest, and residential habitats with high incidence of scrub typhus in Yunnan, China, for nPCR (nested PCR) and qPCR (quantitative real-time PCR) detection of Orientia tsutsugamushi. A total of 4 orders of murine-like animals, Rodentia (87.52%, n = 442), Insectivora (10.29%, n = 52), Lagomorpha (1.79%, n = 9) and Scandentia (0.40%, n = 2) were trapped. Comparing the qPCR infection rates in the three habitats, it was no significant difference that the infection rate of residential habitat (44.44%) and that of the farm habitat (45.05%, P>0.05), which is much larger than that of the forest habitat (3.08%) (P<0.001). Three genotypes (Karp-like, Kato-like and TA763-like) of O. tsutsugamushi were found from Yunnan, China in this study. [ABSTRACT FROM AUTHOR]

Background: Trombiculid mites are globally distributed, highly diverse arachnids that largely lack molecular resources such as whole mitogenomes for the elucidation of taxonomic relationships. Trombiculid larvae (chiggers) parasitise vertebrates and can transmit bacteria (Orientia spp.) responsible for scrub typhus, a zoonotic febrile illness. Orientia tsutsugamushi causes most cases of scrub typhus and is endemic to the Asia-Pacific Region, where it is transmitted by Leptotrombidium spp. chiggers. However, in Dubai, Candidatus Orientia chuto was isolated from a case of scrub typhus and is also known to circulate among rodents in Saudi Arabia and Kenya, although its vectors remain poorly defined. In addition to Orientia, chiggers are often infected with other potential pathogens or arthropod-specific endosymbionts, but their significance for trombiculid biology and public health is unclear. Results: Ten chigger species were collected from rodents in southwestern Saudi Arabia. Chiggers were pooled according to species and screened for Orientia DNA by PCR. Two species (Microtrombicula muhaylensis and Pentidionis agamae) produced positive results for the htrA gene, although Ca. Orientia chuto DNA was confirmed by Sanger sequencing only in P. agamae. Metagenomic sequencing of three pools of P. agamae provided evidence for two other bacterial associates: a spirochaete and a Wolbachia symbiont. Phylogenetic analysis of 16S rRNA and multi-locus sequence typing genes placed the spirochaete in a clade of micromammal-associated Borrelia spp. that are widely-distributed globally with no known vector. For the Wolbachia symbiont, a genome assembly was obtained that allowed phylogenetic localisation in a novel, divergent clade. Cytochrome c oxidase I (COI) barcodes for Saudi Arabian chiggers enabled comparisons with global chigger diversity, revealing several cases of discordance with classical taxonomy. Complete mitogenome assemblies were obtained for the three P. agamae pools and almost 50 SNPs were identified, despite a common geographic origin. Conclusions: P. agamae was identified as a potential vector of Ca. Orientia chuto on the Arabian Peninsula. The detection of an unusual Borrelia sp. and a divergent Wolbachia symbiont in P. agamae indicated links with chigger microbiomes in other parts of the world, while COI barcoding and mitogenomic analyses greatly extended our understanding of inter- and intraspecific relationships in trombiculid mites. [ABSTRACT FROM AUTHOR]

Background: Fever is the most frequent symptom in patients seeking care in South and Southeast Asia. The introduction of rapid diagnostic tests (RDTs) for malaria continues to drive patient management and care. Malaria-negative cases are commonly treated with antibiotics without confirmation of bacteraemia. Conventional laboratory tests for differential diagnosis require skilled staff and appropriate access to healthcare facilities. In addition, introducing single-disease RDTs instead of conventional laboratory tests remains costly. To overcome some of the delivery challenges of multiple separate tests, a multiplexed RDT with the capacity to diagnose a diverse range of tropical fevers would be a cost-effective solution. In this study, a multiplex lateral flow immunoassay (DPP Fever Panel II Assay) that can detect serum immunoglobulin M (IgM) and specific microbial antigens of common fever agents in Asia (Orientia tsutsugamushi, Rickettsia typhi, Leptospira spp., Burkholderia pseudomallei, Dengue virus, Chikungunya virus, and Zika virus), was evaluated. Methodology/Principal findings: Whole blood (WB) and serum samples from 300 patients with undefined febrile illness (UFI) recruited in Vientiane, Laos PDR were tested using the DPP Fever Panel II, which consists of an Antibody panel and Antigen panel. To compare reader performance, results were recorded using two DPP readers, DPP Micro Reader (Micro Reader 1) and DPP Micro Reader Next Generation (Micro Reader 2). WB and serum samples were run on the same fever panel and read on both micro readers in order to compare results. ROC analysis and equal variance analysis were performed to inform the diagnostic validity of the test compared against the respective reference standards of each fever agent (S1 Table). Overall better AUC values were observed in whole blood results. No significant difference in AUC performance was observed when comparing whole blood and serum sample testing, except for when testing for R. typhi IgM (p = 0.04), Leptospira IgM (p = 0.02), and Dengue IgG (p = 0.03). Linear regression depicted R2 values had ~70% agreement across WB and serum samples, except when testing for leptospirosis and Zika, where the R2 values were 0.37 and 0.47, respectively. No significant difference was observed between the performance of Micro Reader 1 and Micro Reader 2, except when testing for the following pathogens: Zika IgM, Zika IgG, and B pseudomallei CPS Ag. Conclusions/Significance: These results demonstrate that the diagnostic accuracy of the DPP Fever Panel II is comparable to that of commonly used RDTs. The optimal cut-off would depend on the use of the test and the desired sensitivity and specificity. Further studies are required to authenticate the use of these cut-offs in other endemic regions. This multiplex RDT offers diagnostic benefits in areas with limited access to healthcare and has the potential to improve field testing capacities. This could improve tropical fever management and reduce the public health burden in endemic low-resource areas. Author summary: Tropical fevers, specifically those caused by non-malarial infectious agents, contribute to considerable morbidity and mortality in the Asia-Pacific region. Diagnosis of these pathogens is challenging since the clinical signs are often indistinguishable. Conventional laboratory tests to differentiate between tropical diseases require substantial infrastructure and experienced staff, limiting access to accurate tests in low-resource endemic regions. Rapid diagnostic tools (RDTs) offer an affordable solution for disease management and patient care. Although RDTs are also available for detecting non-malarial pathogens, there are financial and accessibility issues in establishing multiple separate tests in resource-constrained regions. To overcome these challenges, a multi-detection diagnostic platform with the capacity to diagnose a diverse range of tropical fevers would be a solution. This study aimed to evaluate the accuracy of an easier-to-use multiplex lateral flow immunoassay (DPP Fever Panel II Assay) that can detect IgM antibodies and specific antigens of common tropical diseases in Asia (Scrub typhus, Murine typhus, Leptospirosis, Melioidosis, Dengue virus, Chikungunya, and Zika virus). The test performed offers comparable diagnostic accuracy to commercially available tests, as well as some reference tests. The test also performs at equivalent accuracy with both blood and serum samples. If the fever panel were used as a stand-alone test for acute febrile illness diagnosis, cut-offs would need to be adjusted depending on the use of the test, and the desired sensitivity and specificity. There is a need to investigate the use of these cut-offs in other endemic regions, which could improve the rate of tropical fever diagnosis in low-resource settings. [ABSTRACT FROM AUTHOR]

Mites are highly prevalent arthropods that infest diverse ecological niches globally. Approximately 55,000 species of mites have been identified but many more are yet to be discovered. Of the ones we do know about, most go unnoticed by humans and animals. However, there are several species from the Acariformes superorder that exert a significant impact on global human health. House dust mites are a major source of inhaled allergens, affecting 10–20% of the world's population; storage mites also cause a significant allergy in susceptible individuals; chiggers are the sole vectors for the bacterium that causes scrub typhus; Demodex mites are part of the normal microfauna of humans and their pets, but under certain conditions populations grow out of control and affect the integrity of the integumentary system; and scabies mites cause one of the most common dermatological diseases worldwide. On the other hand, recent genome sequences of mites provide novel tools for mite control and the development of new biomaterial with applications in biomedicine. Despite the palpable disease burden, mites remain understudied in parasitological research. By better understanding mite biology and disease processes, researchers can identify new ways to diagnose, manage, and prevent common mite-induced afflictions. This knowledge can lead to improved clinical outcomes and reduced disease burden from these remarkably widespread yet understudied creatures. [ABSTRACT FROM AUTHOR]

The majority of cases of undifferentiated acute febrile illness (AFI) in the tropics have an undefined etiology. In Thailand, AFI accounts for two-thirds of illnesses reported to the Ministry of Public Health. To characterize the bacterial and viral causes of these AFIs, we conducted molecular pathogen screening and serological analyses in patients who sought treatment in Chum Phae Hospital, Khon Kaen province, during the period from 2015 to 2016. Through integrated approaches, we successfully identified the etiology in 25.5% of cases, with dengue virus infection being the most common cause, noted in 17% of the study population, followed by scrub typhus in 3.8% and rickettsioses in 6.8%. Further investigations targeting viruses in patients revealed the presence of Guadeloupe mosquito virus (GMV) in four patients without other pathogen co-infections. The characterization of four complete genome sequences of GMV amplified from AFI patients showed a 93–97% nucleotide sequence identity with GMV previously reported in mosquitoes. Nucleotide substitutions resulted in amino acid differences between GMV amplified from AFI patients and mosquitoes, observed in 37 positions. However, these changes had undergone purifying selection pressure and potentially had a minimal impact on protein function. Our study suggests that the GMV strains identified in the AFI patients are relatively similar to those previously reported in mosquitoes, highlighting their potential role associated with febrile illness. [ABSTRACT FROM AUTHOR]

Background: To assess etiological factors, severity, complications and mortality due to thrombocytopenia in commonly encountered infections in hospitalised patients of MDM Hospital, DR S N Medical College, Jodhpur during 2021and 2022. Material and Methods: This was a hospital based, observational descriptive study of 310 patients presenting with thrombocytopenia due to infective etiology. Observations and Results: Dengue fever (50.9%) was found to be the most common cause of thrombocytopenia followed by malaria (17.1%), scrub typhus (16.1%), HIV (4.5%), sepsis (2.9%) and enteric fever (2.6%). Very severe thrombocytopenia (<20,000/µl) was seen in 23.2% patients, 47.1% had severe thrombocytopenia (20,000-50,000/µl), 25.8% patients had moderate thrombocytopenia (51,000-1,00,000/µl) and Mild thrombocytopenia (1,00,000-1,50,000/µl) was seen in 3.9% patients. 50.3% patients presented with bleeding manifestations of which petechial rash (15.5%) was the most common. Overall mortality was 3.5% which was higher in patients with Very severe thrombocytopenia, patients of P. falciparum malaria, scrub typhus and those having concomitant infections. Conclusion: Pyrexia with thrombocytopenia is the most commonly encountered condition with myriad connotations. It is important to find out the cause of the thrombocytopenia. Finding etiological diagnosis early is reassuring and rewarding. [ABSTRACT FROM AUTHOR]

Orientia tsutsugamushi is an obligate intracellular bacterium associated with trombiculid mites and is the causative agent of scrub typhus, a life-threatening febrile disease. Strain typing of O. tsutsugamushi is based on its immunodominant surface antigen, 56-kDa type-specific antigen (TSA56). However, TSA56 gene sequence-based phylogenetic analysis is only partially congruent with core genome-based phylogenetic analysis. Thus, this study investigated whether concatenated surface antigen sequences, including surface cell antigen (Sca) proteins, can reflect the genome-scale phylogeny of O. tsutsugamushi. Complete genomes were obtained for two common O. tsutsugamushi strains in Taiwan, TW-1 and TW-22, and the core genome/proteome was identified for 11 O. tsutsugamushi strains. Phylogenetic analysis was performed using maximum likelihood (ML) and neighbor-joining (NJ) methods, and the congruence between trees was assessed using a quartet similarity measure. Phylogenetic analysis based on 691 concatenated core protein sequences produced identical tree topologies with ML and NJ methods. Among TSA56 and core Sca proteins (ScaA, ScaC, ScaD, and ScaE), TSA56 trees were most similar to the core protein tree, and ScaA trees were the least similar. However, concatenated ScaA and TSA56 sequences produced trees that were highly similar to the core protein tree, the NJ tree being more similar. Strain-level characterization of O. tsutsugamushi may be improved by coanalyzing ScaA and TSA56 sequences, which are also important targets for their combined immunogenicity. [ABSTRACT FROM AUTHOR]

Scrub typhus is a re-emerging disease caused by Orientia tsutsugamushi, transmitted by mites belonging to the family Trombiculidae. Humans and rodents acquire the infection by the bite of larval mites/chiggers. Suncus murinus, the Asian house shrew, has been reported to harbor the vector mites and has been naturally infected with O. tsutsugamushi. The present study aimed to localize and record O. tsutsugamushi in the tissues and the host response in shrews naturally infected with O. tsutsugamushi. Sheehan's modified May–Grunwald Giemsa staining was carried out in 365 tissues from 87 animals, and rickettsiae were documented in 87 tissues from 20 animals. Immunohistochemical (IHC) staining, using polyclonal antibodies raised against selected epitopes of the 56-kDa antigen, was carried out, and 81/87 tissue sections were tested positive for O. tsutsugamushi. By IHC, in addition to the endothelium, the pathogen was also demonstrated by IHC in cardiomyocytes, the bronchiolar epithelium, stroma of the lungs, hepatocytes, the bile duct epithelium, the epithelium and goblet cells of intestine, the tubular epithelium of the kidney, and splenic macrophages. Furthermore, the pathogen was confirmed by real-time PCR using blood (n = 20) and tissues (n = 81) of the IHC-positive animals. None of the blood samples and only 22 out of 81 IHC-positive tissues were tested positive by PCR. By nucleotide sequencing of the 56-kDa gene, Gilliam and Karp strains were found circulating among these animals. Although these bacterial strains are highly virulent and cause a wide range of pathological alterations, hence exploring their adaptive mechanisms of survival in shrews will be of significance. Given that the pathogen localizes in various organs following a transient bacteremia, we recommend the inclusion of tissues from the heart, lung, intestine, and kidney of reservoir animals, in addition to blood samples, for future molecular surveillance of scrub typhus. [ABSTRACT FROM AUTHOR]

Abstract Background Tsutsugamushi, also known as bush typhus, is a naturally occurring disease caused by Orientia tsutsugamushi. We reported a case of vertical mother-to-newborn transmission of Orientia tsutsugamushi infection in a newborn from Yunnan (China). Case presentation Decreased fetal movements were observed at 39 weeks of gestation. After birth, the newborn (female) had recurrent fever, shortness of breath, and bruising around the mouth and extremities. At 5 h 58 min of age, the newborn was admitted for fever, shortness of breath and generalized rash. The liver was palpable 3 cm below the costal margin, and the limbs showed pitting edema. There was subcutaneous bleeding. Investigations suggested heavy infection, myocardial damage, decreased platelets. Treatment with cefotaxime and ampicillin failed. The mother was hospitalized at 29 weeks of gestation with a fever for 4 consecutive days, and an ulcerated crust was found in the popliteal fossa. Due to this pregnancy history, A diagnosis of Orientia tsutsugamushi infection was suspected in our index case and confirmed by macrogenomic testing and she was treated with vancomycin and meropenem, and later azithromycin for 1 week. The newborn was discharged in good general condition, gradually normalizing body temperature, and decreasing rash and jaundice. There were no abnormalities on subsequent blood macrogenomic tests for the baby. And one month later she showed good mental health, sleep, and food intake and no fever, rash, or jaundice. Conclusion Determining the cause of symptoms is the key to treating diseases, especially the rare diseases that can be misdiagnosed. Suitable for people with Infectious Diseases; Neonatology; Obstetrics.

Plasmacytoid dendritic cells (pDCs) produce type I interferons (IFNs) after sensing viral/bacterial RNA or DNA by toll-like receptor (TLR) 7 or TLR9, respectively. However, aberrant pDCs activation can cause adverse effects on the host and contributes to the pathogenesis of type I IFN-related autoimmune diseases. Here, we show that heparin interacts with the human pDCs-specific blood dendritic cell antigen 2 (BDCA-2) but not with related lectins such as DCIR or dectin-2. Importantly, BDCA-2-heparin interaction depends on heparin sulfation and receptor glycosylation and results in inhibition of TLR9-driven type I IFN production in primary human pDCs and the pDC-like cell line CAL-1. This inhibition is mediated by unfractionated and low-molecular-weight heparin, as well as endogenous heparin from plasma, suggesting that the local blood environment controls the production of IFN-a in pDCs. Additionally, we identified an activation-dependent soluble form of BDCA-2 (solBDCA-2) in human plasma that functions as heparin antagonist and thereby increases TLR9-driven IFN-a production in pDCs. Of importance, solBDCA-2 levels in the serum were increased in patients with scrub typhus (an acute infectious disease caused by Orientia tsutsugamushi) compared to healthy control subjects and correlated with anti-dsDNA antibodies titers. In contrast, solBDCA-2 levels in plasma from patients with bullous pemphigoid or psoriasis were reduced. In summary, this work identifies a regulatory network consisting of heparin, membrane-bound and solBDCA-2 modulating TLR9-driven IFN-a production in pDCs. This insight into pDCs function and regulation may have implications for the treatment of pDCs-related autoimmune diseases. [ABSTRACT FROM AUTHOR]

Rickettsiosis is caused by Orientia spp. and Rickettsia spp., arthropod-borne zoonotic intracellular bacteria. The close relationships between pet dogs, cats and owners increase the risk of rickettsial transmission, with limited studies on the seroprevalence in pets. This study investigated the prevalence of rickettsia exposure among dogs and cats in Bangkok and neighboring provinces. The samples from 367 dogs and 187 cats used in this study were leftover serum samples from routine laboratory testing stored at the Veterinary Teaching Hospital. In-house Enzyme-linked immunosorbent assay (ELISA) tests included IgG against the scrub typhus group (STG), typhus group (TG), and spotted fever group (SFG). The seroprevalence in pet dogs was 30.25% (111/367), including 21.53% for STG, 4.36% for TG, and 1.09% for SFG. Co-seroprevalence consisted of 2.72% for STG and TG, 0.27% for STG and SFG, and 0.27% for pangroup infection. The prevalence in cats was 62.56% (117/187), including 28.34% for STG, 4.28% for TG, and 6.42% for STG. Co-seroprevalence in cats consisted of STG and TG (4.28%), STG and SFG (5.35%), TG and SFG (3.21%), and three-group infection (10.69%). No significant difference in seroprevalence for the three serogroups was observed in any of the 64 districts sampled. The mean hematocrit level significantly decreased in seropositive dogs (P<0.05). Seropositive dogs and cats were detected in significantly greater numbers of anemia cases than nonanemia cases (P<0.05) (odds ratio: 7.93, 0.44, p = 0.00, p = 0.01). A significantly higher number of seropositive cats had decreased hemoglobin levels (P<0.05) (odds ratio: 3.63, p = 0.00). The seropositive samples significantly differed among older cats (P<0.05). These high exposures in pet dogs and cats could constitute important relationship dynamics between companion animals and rickettsial vectors. Significantly decreased hematocrit and hemoglobin levels indicated anemia in the exposed dogs and cats. The study findings will raise awareness of this neglected disease among pet owners and veterinary hospital personnel and aid in future public health preventative planning. [ABSTRACT FROM AUTHOR]

The reported cases of scrub typhus (ST) have continued to escalate, with outbreaks occurring regionally in China. These pose an increasing public health threat at a time when public health has been overwhelmed. During the period from July to August 2022, in Rongjiang County, Guizhou Province, China, 13 out of 21 fever patients were diagnosed with scrub typhus, based on epidemiological investigation and blood test analysis. The major clinical symptoms of these patients showed fever, chills, headache, eschar, fatigue and pneumonia, which were accompanied by a rise in C-reactive protein, neutrophils, alanine transaminase (ALT) and aspartate aminotransferase (AST). Furthermore, nearly half of them exhibited abnormal electrocardiogram activity. Through semi-nested PCR, Sanger sequencing and phylogenetic tree construction, the Karp strain of Orientia tsutsugamushi (O. tsutsugamushi) was confirmed as the pathogen causing ST in Rongjiang County, which shared the same evolutionary branch with O. tsutsugamushi isolated from wild mouse liver or spleen, indicating that the wild mouse plays an important role in transmitting the disease. In contrast to the sporadic cases in the past, our study is the first to disclose an epidemic and the corresponding clinical characteristics of ST in Guizhou province, which is of great significance for the prevention and treatment of regional illnesses. Author summary: In this study, 13 cases of ST were identified through clinical and laboratory diagnosis in Rongjiang County, which is the first outbreak of the disease in Guizhou province, China. It is worth noting that ST was caused by the Karp strain, which can be transmitted by wild mice, and the infected population generally had a clear history of outdoor activity. In addition to the typical clinical symptoms such as fever, chills and pneumonia, nearly half of patients with ST also exhibited abnormal electrocardiogram activity. In conclusion, our study presents a method to confirm ST through the combination of clinical and laboratory diagnosis, which provides a reference for the development of effective strategies and measures to tackle ST, and has important public health significance. [ABSTRACT FROM AUTHOR]

Background: Scrub typhus, caused by the bacterium Orientia tsutsugamushi, is a vector-borne disease transmitted to humans through the bite of infected chiggers. It is endemic to the Asia-Pacific region and is associated with significant morbidity and mortality if left untreated. Methods: In this retrospective study, we analyzed the clinical features, laboratory findings, and complications in 40 patients diagnosed with scrub typhus at a tertiary care center between 2020-2022 Data were extracted from medical records and analyzed using descriptive and inferential statistics. Results: The study population comprised patients aged 17-75 years, with a relatively equal distribution across genders. Fever, headache, and myalgia were the most common presenting symptoms, while thrombocytopenia and leukocytosis were frequent laboratory findings. Complications such as acute kidney injury, hyponatremia, and hepatic injury were observed in a subset of patients. C-reactive protein (CRP) levels showed a significant positive correlation with total white count but not with the duration of fever or other clinical parameters. Conclusion: This study provides insights into the epidemiology, clinical presentation, and laboratory features of scrub typhus in our setting. The findings underscore the importance of early recognition and comprehensive management of scrub typhus to mitigate its morbidity and mortality. Further research is warranted to elucidate the pathophysiological mechanisms underlying the disease and improve diagnostic and treatment strategies. [ABSTRACT FROM AUTHOR]

Background and Aims: Scrub typhus is an endemic disease in the fall season that occurs in a limited number of places known as the Tsutsugamushi Triangle. Peripheral neuropathy is a common complication of scrub typhus. Herein, we encountered several patients with ascending paralysis after scrub typhus infection, who were diagnosed with Guillain‐Barré syndrome (GBS). We aimed to investigate the clinical and laboratory characteristics of patients who developed GBS after scrub typhus. Methods: Patients were retrospectively recruited from six nationwide tertiary centers in South Korea from January 2017 to December 2021. Patients who had been clinically diagnosed with GBS and confirmed to have scrub typhus via laboratory examination and/or the presence of an eschar before the onset of acute limb paralysis were included. The GBS‐associated clinical and electrophysiological characteristics, outcomes, and scrub typhus‐associated features were collected. Results: Of the seven enrolled patients, six were female and one was male. The median time from scrub typhus infection to the onset of limb weakness was 6 (range: 2–14) days. All patients had eschar on their bodies. Four patients (57.1%) were admitted to the intensive care unit and received artificial ventilation for respiratory distress. At 6 months, the median GBS disability score was 2 (range, 1–4) points. Interpretation: Patients with scrub typhus‐associated GBS have a severe clinical presentation and require intensive treatment with additional immunotherapies. Therefore, GBS should be included in the differential diagnosis when peripheral neuropathies develop during scrub typhus treatment. Notably, scrub typhus is associated to GBS. [ABSTRACT FROM AUTHOR]

Acute Kidney Injury (AKI) associated with Scrub typhus is an emerging health problem which is more common in the tropics including India. This study intended to find out the occurrence of Scrub typhus among the Community Acquired Acute Kidney Injury patients in a tertiary care hospital in Assam, North East India. AKI patients with acute febrile illness admitted to Gauhati Medical College and Hospital, Guwahati, Assam were included in the study and demographic characteristics along with clinical features were recorded. The detection of Scrub typhus was done by IgM Enzyme Linked Immunosorbent Assay (ELISA) test (Optical Density > 0.5) and polymerase chain reaction (PCR) analysis. Routine haematological and biochemical tests were performed. Molecular characterization of Orientia tsutsugamushi was done followed by phylogenetic analysis. The Graph Pad Prism software 9 was used for statistical analysis. Out of 221 AKI patients admitted to hospital, 45 patients (20.4%) were confirmed to be Scrub typhus positive and among them, 4 cases were co-infected with leptospirosis. Majority of Scrub typhus positive AKI patients were in Stage I (82.2%) under KDIGO guideline. "Karp" was the predominant circulating serotype. The study showed cases of Scrub typhus associated Acute Kidney Injury was high and mortality was 11.1%. Hence, in this region, further studies need to be done with large number of population and more emphasis need to be given on differential diagnosis. [ABSTRACT FROM AUTHOR]

Scrub typhus is a vector-borne infection caused by the obligate intracellular organism Orientia tsutsugamushi. In some cases, scrub typhus can result in severe complications, multiorgan failure and death. To study the clinical and laboratory profiles of patients who succumbed to scrub typhus. A prospective cohort study was conducted from August 2019 through April 2023 on scrub typhus patients admitted to our hospital. Clinical and laboratory parameters of all the patients were recorded, and blood samples were drawn. To confirm scrub typhus, a nested polymerase chain reaction (nPCR) was performed in collected samples. Viable amplicons were sequenced, and phylogenetic analyses were performed to identify infecting genotypes. A total of 261 patients were enrolled. Of these, nine (3.45%) patients succumbed at a median (Interquartile Range) duration of 5 (1.5, 10.5) days after admission. Sepsis with septic shock (9, 100%) and acute kidney injury (AKI) (6, 66%) were noted among the succumbed patients. All the succumbed patients (100%) required intensive care admission, inotropic and ventilatory support. While 5 (55%) patients required dialysis, two (22%) required blood transfusion. Three (33%) patient samples were co-positive for Leptospira IgM, and four (44%) patients had superinfection with Candida tropicalis, multi-drug-resistant (MDR) E. Coli sepsis, pan drug-resistant (PDR) Acinetobacter Baumanii, and Klebsiella pneumoniae. Phylogenetic analysis revealed Orientia tsutsugamushi Japanese Gilliam-variant (JG-v) like (50%), Karp-like (37.5%), and Japanese Gilliam (JG) like (12.5%) strains among succumbed patients. Delay in scrub typhus diagnosis can result in severe complications, septic shock, and multisystem organ failure, culminating in death. [ABSTRACT FROM AUTHOR]

Outbreaks of acute encephalitis syndrome (AES) with unknown aetiology are reported every year in Gorakhpur district, Uttar Pradesh, India, and Orientia tsutsugamushi, the rickettsial pathogen, responsible for scrub typhus has been attributed as the primary cause of AES problem. However, information on the prevalence of other rickettsial infections is lacking. Hence, this study was carried out to assess any occurrence of tick‐ and flea‐borne rickettsial agents in villages reporting AES cases in this district. In total, 825 peridomestic small mammals were trapped, by setting 9254 Sherman traps in four villages with a trap success rate of 8.9%. The Asian house shrew, Suncus murinus, constituted the predominant animal species (56.2%) and contributed to the maximum number (87.37%) of ectoparasites. In total, 1552 ectoparasites comprising two species of ticks and one species each of flea and louse were retrieved from the trapped rodents/shrews. Rhipicephalus sanguineus, the brown dog tick, was the predominant species retrieved from the trapped rodents/shrews, and the overall infestation rate was 1.75 per animal. In total, 4428 ectoparasites comprising five tick species, three louse species and one flea species were collected from 1798 domestic animals screened. Rhipicephalus microplus was the predominant tick species collected from the domestic animals. The cat flea, Ctenocephalides felis, constituted 1.5% of the total ectoparasites. Of all the ectoparasite samples (5980) from domestic animals and rodents, tested as 1211 pools through real‐time PCR assays, 64 pools were positive for 23S rRNA gene of rickettsial agents. The PCR‐positive samples were subjected to multi‐locus sequence typing (MLST). In BLAST and phylogenetic analysis, the ectoparasites were found to harbour Rickettsia asembonensis (n = 9), Rickettsia conorii (n = 3), Rickettsia massiliae (n = 29) and Candidatus Rickettsia senegalensis (n = 1). A total of 22 pools were detected to have multiple rickettsial agents. The prevalence of fleas and high abundance of tick vectors with natural infections of rickettsial agents indicates the risk of transmission of tick‐ and flea‐borne rickettsial diseases in rural villages of Gorakhpur. Further epidemiological studies are required to confirm the transmission of these agents to humans. [ABSTRACT FROM AUTHOR]

Scrub typhus is one of the most neglected tropical diseases, a leading cause of acute undifferentiated febrile illness in areas of the 'tsutsugamushi triangle', diagnosed frequently in South Asian countries. The bacteria Orientia tsutsugamushi is the causative agent of the disease, which enters the human body through the bite of trombiculid mites (also known as chiggers) of the genus Leptotrombidium deliense. Diagnosis of the disease is challenging, as its early symptoms mimic other febrile illnesses like dengue, influenza and corona viruses. Lack of rapid, reliable and cost-effective diagnostic methods further complicates the identification process. Northeast India, a mountainous region with a predominantly rural tribal population, has witnessed a resurgence of scrub typhus cases in recent years. Various ecological factors, including rodent populations, habitat characteristics and climatic conditions, influence its prevalence. Entomological investigations have confirmed the abundance of vector mites, highlighting the importance of understanding their distribution and the probability of transmission of scrub typhus in the region. Proper diagnosis, awareness campaigns and behavioural interventions are essential for controlling scrub typhus outbreaks and reducing its impact on public health in Northeast India. Further research and community-based studies are necessary to accurately assess the disease burden and implement effective prevention strategies. [ABSTRACT FROM AUTHOR]

Background: Large-scale outbreaks of scrub typhus combined with its emergence in new areas as a vector-borne rickettsiosis highlight the ongoing neglect of this disease. This study aims to explore the long-term changes and regional leading factors of scrub typhus in China, with the goal of providing valuable insights for disease prevention and control. Methods: This study utilized a Bayesian space–time hierarchical model (BSTHM) to examine the spatiotemporal heterogeneity of scrub typhus and analyze the relationship between environmental factors and scrub typhus in southern and northern China from 2006 to 2018. Additionally, a GeoDetector model was employed to assess the predominant influences of geographical and socioeconomic factors in both regions. Results: Scrub typhus exhibits a seasonal pattern, typically occurring during the summer and autumn months (June to November), with a peak in October. Geographically, the high-risk regions, or hot spots, are concentrated in the south, while the low-risk regions, or cold spots, are located in the north. Moreover, the distribution of scrub typhus is influenced by environment and socio-economic factors. In the north and south, the dominant factors are the monthly normalized vegetation index (NDVI) and temperature. An increase in NDVI per interquartile range (IQR) leads to a 7.580% decrease in scrub typhus risk in northern China, and a 19.180% increase in the southern. Similarly, of 1 IQR increase in temperature reduces the risk of scrub typhus by 10.720% in the north but increases it by 15.800% in the south. In terms of geographical and socio-economic factors, illiteracy rate and altitude are the key determinants in the respective areas, with q-values of 0.844 and 0.882. Conclusions: These results indicated that appropriate climate, environment, and social conditions would increase the risk of scrub typhus. This study provided helpful suggestions and a basis for reasonably allocating resources and controlling the occurrence of scrub typhus. [ABSTRACT FROM AUTHOR]

Background: Scrub typhus, caused by Orientia tsutsugamushi, is an acute febrile illness with symptoms such as fever, chills, and organ failure. The similar clinical presentation in other common diseases such as malaria, dengue fever, and typhoid fever creates difficulty and delay in the clinical diagnosis of scrub typhus. This delay may increase the risk of scrub typhus complications. In India, it is a public health issue with a paucity of data. Aims and Objectives: This study aims to evaluate the clinical characteristics, outcomes, and prognostic factors of patients with scrub typhus. Materials and Methods: This institutional-based observational, cross-sectional study was conducted among consecutively selected 154 adult patients suffering from scrub typhus at a Medical College Hospital situated in the southern part of West Bengal, India. All data were collected according to a pre-designed proforma. At the end of the study, results were analyzed statistically. Results: Younger, females, and homemakers are more susceptible to scrub typhus, mostly in the post-monsoon season from July to November. The incidence of scrub typhus complications is high in the southern part of West Bengal. The case fatality rate of scrub typhus is 6.5%. Male sex, pre-hospitalization duration of illness more than 7 days, presence of diabetes mellitus, serum creatinine (Scr) more than 1.5 mg/dL, serum bilirubin more than 3 mg/dL, systolic blood pressure below 90 mmHg, altered sensorium, and acute respiratory distress syndrome were associated with poor prognosis. Conclusion: A high degree of clinical suspicion is required for the early diagnosis of scrub typhus and the factors associated with poor prognosis must be considered to reduce morbidity and mortality. [ABSTRACT FROM AUTHOR]