Scrub Typhus Leading to Acute Encephalitis Syndrome, Assam, India

Aetiological profile of acute encephalitis syndrome in Assam, India, during a 4-year period from 2019 to 2022

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.

Development and implementation of a strategy for early diagnosis and management of scrub typhus: an emerging public health threat

Scrub typhus, caused by Orientia tsutsugamushi, is a re-emerging zoonotic disease in the tropics with considerable morbidity and mortality rates. This disease, which is mostly prevalent in rural areas, remains underdiagnosed and underreported because of the low index of suspicion and non-specific clinical presentation. Limited access to healthcare, diagnostics, and treatment in rural settings further makes it challenging to distinguish it from other febrile illnesses. While easily treatable, improper treatment leads to severe forms of the disease and even death. As there is no existing public health program to address scrub typhus in India, there is an urgent need to design a program and test its effectiveness for control and management of the disease. With this backdrop, this implementation research protocol has been developed for a trial in few of the endemic "pockets" of Odisha, an eastern Indian state that can be scalable to other endemic areas of the country, if found effective. The main goal of the proposed project is to include scrub typhus as a differential diagnosis of fever cases in every tier of the public health system, starting from the community level to the health system, for the early diagnosis among suspected cases and to ensure that individuals receive complete treatment. The current study aimed to describe the protocol of the proposed Scrub Typhus Control Program (STCP) in detail so that it can receive valuable views from peers which can further strengthen the attempt.

Scrub typhus in Northeast India: epidemiology, clinical presentations, and diagnostic approaches

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.

Scrub Typhus- An Underestimated Infectious Disease Attributable to Community Acquired Acute Kidney Injury

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.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12088-023-01137-x.

Phylogenetic and immunological investigations of complete TSA56 ORF of Orientia tsutsugamushi present in acute encephalitis syndrome cases from eastern Uttar Pradesh, India

Scrub typhus (ST) caused by Orientia tsutsugamushi (OT), has long been known to cause acute encephalitis syndrome (AES) and acute febrile illness (AFI). The immunodominant 56 kDa protein of OT, which is encoded by the 56 kDa gene (1600 bp encoding 516-541 amino acids) is a commonly studied antigen for genotype and serotype assignment. Previous studies from India have utilized partial type specific antigen (TSA) 56 kDa sequences for OT strain characterisation. On the other hand, understanding the antigenic diversity of current OT strains, is critical for developing specific diagnostic tests and vaccines against ST. As a result, the current study analyses antigenic variants using the entire TSA56 ORF of OT from AES cases. Phylogenetic investigation using complete TSA56 ORF sequences revealed Karp and Gilliam were the circulating predominant strains of OT. Furthermore, Immuno-informatical analysis demonstrated that the majority of high-binding affinity CD4 TCEs against the most prevalent Indian human leukocyte antigen alleles were present in the S-VDIII/IV and S-VDIV spacer regions of TSA56 ORF. TSA56 conserved spacer is crucial for OT immunological response investigations. Further, the pathophysiological effects of spacer domains in ST require further investigation. Furthermore, the characterization of the TSA56 spacer region of the OT from different parts of India is critical for developing region-specific ST diagnostic assays and vaccines.

Etiological Profile and Clinico Epidemiological Patterns of Acute Encephalitis Syndrome in Tamil Nadu, India

Introduction

Establishing the etiological cause of acute encephalitis syndrome (AES) is challenging due to the distinct distribution of various etiological agents. This study aims to determine the etiological profiles of both viruses and bacteria and their associated clinico-epidemiological features among the AES suspected cases in Tamil Nadu, India.

Methods

Samples of 5136 suspected AES cases from January 2016 to December 2020 (5 years) were subjected to the detection of etiological agents for AES through serological and molecular diagnosis methods. Further, the clinical profile, age- and gender-wise susceptibility of cases, co-infection with other AES etiological agents, and seasonality pattern with respect to various etiological agents were examined.

Results

AES positivity was established in 1480 cases (28.82%) among the 5136 suspected cases and the positivity for male and female groups were 57.77% and 42.23%, respectively. The pediatric group was found to be more susceptible than others. Among the etiological agents tested, the Japanese encephalitis virus (JEV) was the predominant followed by Cytomegalovirus, Herpes Simplex virus, Epstein-Barr virus, Varicella Zoster virus, and others. Co-infection with other AES etiological agents was observed in 3.5% of AES-positive cases. Seasonality was observed only for vector-borne diseases such as JEV, dengue virus, and West Nile virus infections in this study.

Conclusion

AES was found to be a significant burden for Tamil Nadu with a diverse etiological spectrum including both sporadic and outbreak forms. Overlapping clinical manifestations of AES agents necessitate the development of region-specific diagnostic algorithm with distinct etiological profiles for early detection and effective case management.

Association of Scrub Typhus in Children with Acute Encephalitis Syndrome and Meningoencephalitis, Southern India

Scrub typhus is an established cause of acute encephalitis syndrome (AES) in northern states of India. We systematically investigated 376 children with AES in southern India, using a stepwise diagnostic strategy for the causative agent of scrub typhus, Orientia tsutsugamushi, including IgM and PCR testing of blood and cerebrospinal fluid (CSF) to grade its association with AES. We diagnosed scrub typhus in 87 (23%) children; of those, association with AES was confirmed in 16 (18%) cases, probable in 55 (63%), and possible in 16 (18%). IgM detection in CSF had a sensitivity of 93% and specificity of 82% compared with PCR. Our findings suggest scrub typhus as an emerging common treatable cause of AES in children in southern India and highlight the importance of routine testing for scrub typhus in diagnostic algorithms. Our results also suggest the potential promise of IgM screening of CSF for diagnosis of AES resulting from scrub typhus.

Scrub Typhus Meningoencephalitis: An Overlooked Entity

Scrub typhus is common in rural parts of Nepal, but its diagnosis remains difficult due to a lack of clinical suspicion and poor diagnostic resources. The absence of common clinical features further complicates this problem. Acute kidney injury (AKI), myocarditis, rhabdomyolysis, hepatitis, acute respiratory distress syndrome, and meningoencephalitis are complications of the disease associated with high mortality. Overlap findings can be noted in scrub typhus meningoencephalitis and other tropical infections. This makes diagnosing the disease more challenging, especially in areas where the burden of infectious diseases is high. We report three cases of scrub typhus meningoencephalitis. All three patients were treated successfully with doxycycline. Because patients with scrub typhus have an excellent response to treatment, delay in treatment and rate of complications can be prevented with high clinical suspicion of the condition.

Prevalence, clinico-laboratory features, and the functional outcome of children with scrub typhus meningoencephalitis-a cohort study

Scrub typhus is being reported as the most common cause of childhood meningoencephalitis (ME) in India. Hence, we planned to estimate the proportion of scrub typhus infection among children aged 1 month to 12 years with the clinical diagnosis of ME and to evaluate their demographic, clinical and laboratory characteristics. This cohort study was conducted in the Department of Pediatrics of a tertiary care teaching hospital in south India. One hundred and twenty-seven consecutive children aged 1 month to 12 years with the clinical diagnosis of ME were the participants. Their socio-demographic factors, clinical details, laboratory reports and outcomes were analyzed. The etiological agent was identified in 71 (56%) children. Orientia tsutsugamushi (Scrub typhus) was the most common infection (24.4%), of all children with ME. Children aged ≥5 years were frequently affected by scrub typhus ME. Eschar, capillary leak, hepatomegaly and splenomegaly were the predominant clinical features of scrub typhus ME. Thrombocytopenia and deranged liver function tests were common in scrub typhus ME. To conclude, Orientia tsutsugamushi was the most common organism identified in our study. Prompt recognition of some tell-tale clinical signs of scrub typhus (such as eschar, thrombocytopenia and hepatosplenomegaly), and timely initiation of antibiotics would lead to better outcomes as evident from the study.

Molecular characterization and evolutionary analysis of Orientia tsutsugamushi in eastern Indian population

Scrub typhus is a bacterial zoonotic acute febrile illness (AFI) caused by the obligate intracellular bacterium Orientia tsutsugamushi, which is an antigenically diverse strain frequently observed in the tropical region of Southeast Asian countries. The recent investigation was conducted to delineate the genotype identification of Orientia tsutsugamushi predominating in the eastern zone of India such as Odisha to decipher its strain type, and evaluate its diversity as well as evolutionary pattern based on the nucleotide analysis of the immune dominant 56 KDa gene. During this study, we have investigated 100 clinical samples (2014-2018), out of which 28 were positive for scrub typhus followed by its molecular characterization and phylogenetic analysis utilizing 56 KDa partial genes. Population genetic parameters showed the presence of 287 polymorphic sites within the analyzed 56 KDa gene. The gene diversity (Hd) and sequence diversity (π) was estimated 0.638 and 0.280, respectively. Selection pressure analysis (θ = dN/dS) having the value 0.222 suggests that the gene lied under purifying selection. The present study suggested a high rate of genetic diversity within the isolates. This research study sheds light on the hereditary and evolutionary relationships of Orientia strains found in the eastern Indian population. Understanding regional genetic variation is critical for vaccine development and sero-diagnostics methods. A significant level of genetic variability was observed during this study. This information has a way to understand more about antigen diversity that leads to develop an effective vaccine candidate for this pathogen.

Scrub Typhus and its co-infection with Leptospirosis at a tertiary care hospital in Uttar Pradesh

The diagnosis of Scrub Typhus is now improving with the availability of an array of serological tests at the majority of diagnostic centres and of molecular tests at advanced laboratories. Our study focuses on evaluating the spectrum of Scrub Typhus and its coinfection with Leptospirosis in patients presenting with acute febrile illness. A total of 1743 blood samples were collected from both In and Out Patient Department (OPD) patients and analyzed for anti Orientia tsutsugamushi and anti-Leptospira IgM antibodies. Our study showed the presence of Scrub Typhus IgM antibodies in 20.7% of all the cases of acute febrile illness. We also found an interesting correlation of Scrub Typhus with Leptospirosis owing to the presence of co-infection in 8.4% of Scrub Typhus cases paving a way for future research in this regard.

Diagnosis of Indigenous Non-Malarial Vector-Borne Infections from Malaria Negative Samples from Community and Rural Hospital Surveillance in Dhalai District, Tripura, North-East India

The aetiology of non-malaria vector-borne diseases in malaria-endemic, forested, rural, and tribal-dominated areas of Dhalai, Tripura, in north-east India, was studied for the first time in the samples collected from malaria Rapid Diagnostic Kit negative febrile patients by door-to-door visits in the villages and primary health centres. Two hundred and sixty serum samples were tested for the Dengue NS1 antigen and the IgM antibodies of Dengue, Chikungunya, Scrub Typhus (ST), and Japanese Encephalitis (JE) during April 2019-March 2020. Fifteen Dengue, six JE, twelve Chikungunya, nine ST and three Leptospirosis, and mixed infections of three JE + Chikungunya, four Dengue + Chikungunya, three Dengue + JE + Chikungunya, one Dengue + Chikungunya + ST, and one Dengue + ST were found positive by IgM ELISA tests, and four for the Dengue NS1 antigen, all without any travel history. True prevalence values estimated for infections detected by Dengue IgM were 0.134 (95% CI: 0.08-0.2), Chikungunya were 0.084 (95% CI: 0.05-0.13), Scrub were 0.043 (95% CI: 0.01-0.09), and Japanese Encephalitis were 0.045 (95% CI: 0.02-0.09). Dengue and Chikungunya were associated significantly more with a younger age. There was a lack of a defined set of symptoms for any of the Dengue, Chikungunya, JE or ST infections, as indicated by the k-modes cluster analysis. Interestingly, most of these symptoms have an overlapping set with malaria; thereby, it becomes imperative that malaria and these non-malaria vector-borne disease diagnoses are made in a coordinated manner. Findings from this study call for advances in routine diagnostic procedures and the development of a protocol that can accommodate, currently, in practicing the rapid diagnosis of malaria and other vector-borne diseases, which is doable even in the resource-poor settings of rural hospitals and during community fever surveillance.

Seasonal abundance of Leptotrombidium deliense, the vector of scrub typhus, in areas reporting acute encephalitis syndrome in Gorakhpur district, Uttar Pradesh, India

The rickettsial pathogen Orientia tsutsugamushi, causing scrub typhus, has been implicated as a major cause of acute encephalitis syndrome (AES) in many places in India including Gorakhpur district of Uttar Pradesh. Seasonal abundance of the principal vector mite of the pathogen, Leptotrombidium deliense, its animal hosts, and prevalence of infection on them are important attributes in the assessment of outbreaks of the disease. Hence, these aspects were investigated, seasonally, in rural villages of Gorakhpur district, where peak incidence of AES cases were reported. A total of 903 animals (rodents/shrews) was collected using 6484 Sherman traps in eight study villages (14% overall trap rate). A sum of 5526 trombiculid mites comprising 12 species was collected from 676 live rodents/shrews screened. Suncus murinus, the Asian house shrew was the predominant species (67%). Among trombiculids, the principal vector mite, L. deliense, was predominant (64.7%) and its infestation index (i.e., average number of chiggers per host animal) was 5.3. The L. deliense infestation index was higher during July to November with a peak in October. Out of 401 animal sera samples screened, 68% were positive for antibodies against O. tsutsugamushi. Of 465 blood samples tested by nested PCR, seven were positive for the 56 kDa gene of O. tsutsugamushi. In conventional PCR, 41 out of 265 samples were positive for the 60 kDa groEL gene of O. tsutsugamushi. Among the 5526 mite samples, tested as 352 pools through nested PCR, four pools were positive for 56 kDa gene. Phylogenetic analysis of 56 and 60 kDa genes confirmed circulation of Karp and TA678 (rodents) and TA678 (mite) serotypes of O. tsutsugamushi in Gorakhpur. Peak incidence of AES in Gorakhpur district occurs during the rainy season (July-October), coinciding with the peak abundance of L. deliense. These results indicate involvement of L. deliense as the vector mite transmitting the scrub typhus pathogen O. tsutsugamushi to humans in the rural areas of Gorakhpur district, India.

Spotted Fever Group Rickettsiae among Children with Acute Febrile Illness, in Gorakhpur, India

Seasonal outbreaks of acute encephalitis syndrome have been occurring in Gorakhpur division in the Indian state of Uttar Pradesh during monsoon and post-monsoon months. Orientia tsutsugamushi was identified as the major aetiology of these outbreaks. Orientia tsutsugamushi was also identified as one of the important aetiology of febrile illness among children attending peripheral health facilities. The present study was undertaken to detect antibodies against spotted fever group rickettsiae (SFGR) and typhus group rickettsiae (TGR) among children with acute febrile illness presenting at peripheral health facilities in Gorakhpur district. Of the 224 blood samples tested, SFGR infection was detected in 13 (6%) patients. None of the samples tested positive for TGR.

Molecular Detection and Genetic Characterization of Orientia tsutsugamushi from Hospitalized Acute Encephalitis Syndrome Cases During Two Consecutive Outbreaks in Eastern Uttar Pradesh, India

Background: Seasonal outbreaks of acute encephalitis syndrome (AES) have been reported especially in the pediatric population with a high case fatality rate in Eastern Uttar Pradesh, India. Orientia tsutsugamushi (OT) is a causative agent of scrub typhus that has been recently identified as a major cause of AES. However, the specific genotypes of OT responsible for AES cases of this region are not known. Therefore, the present study was undertaken to understand the molecular epidemiology of OT prevailing in the AES endemic Eastern Uttar Pradesh region of India. Methods: The study was conducted on 2529 hospitalized AES cases from August 2016 to December 2017. The presence of antibodies against OT from cerebrospinal fluid (CSF) and serum samples were tested using OT IgM enzyme-linked immunosorbent assay (ELISA), whereas OT DNA was tested from whole blood and CSF specimens targeting the partial gene of 56 kDa using nested PCR. Phylogenetic analysis was conducted with sequences (n = 241) generated in this study. Findings: Among the studied AES cases, 50% were found positive for antibodies against OT, whereas 37% of cases were positive for OT DNA. The genetic analysis study revealed that Gilliam (93.8%) is the prevailing genotype of OT followed by Karp (6.16%) genotype in AES cases. Furthermore, the Gilliam strains of this study showed they were >99% identical to earlier reported Gilliam strains from AES cases. Conclusion: We observed the presence of two main OT genotypes in AES cases, among which the majority of OT genotypes fall under the Gilliam clade. The understanding of predominant genotype will be beneficial for its future implications in vaccine development strategies and the development of rapid diagnostic tests.

Outbreak prone communicable diseases of public health importance in the northern districts of West Bengal - Current status & the way forward

India is perilously poised on the threshold of an explosion of infectious diseases, some of which have witnessed re-emergence while others await apposite opportunity to do so. The State of West Bengal is uniquely positioned with its innate geographical vulnerabilities that favour outbreaks of a host of infectious diseases. The northern districts of this State are well known endemic areas for many outbreak prone communicable diseases like malaria, Japanese encephalitis, scrub typhus, dengue and kala-azar. An outbreak of Nipah virus in the recent past is a pointer towards the emerging and re-emerging threat in these regions and warrants urgent prioritization for surveillance and monitoring of these diseases. Identification of risk factors, challenges in delivery of primary healthcare, implementation of intervention strategies along with strengthening of healthcare setup are also the need of the hour. Multisectoral initiatives with emphasis on understanding the complex and rapidly evolving human-animal-vector dynamics as envisaged under the ‘One Health’ concept are indubitably important pillars in the effective management of these emerging public health challenges.

Emerging infectious encephalitides

PURPOSE OF REVIEW

The COVID-19 pandemic has cast increased attention on emerging infections. Clinicians and public health experts should be aware of emerging infectious causes of encephalitis, mechanisms by which they are transmitted, and clinical manifestations of disease.

RECENT FINDINGS

A number of arthropod-borne viral infections -- transmitted chiefly by mosquitoes and ticks -- have emerged in recent years to cause outbreaks of encephalitis. Examples include Powassan virus in North America, Chikungunya virus in Central and South America, and tick-borne encephalitis virus in Europe. Many of these viruses exhibit complex life cycles and can infect multiple host animals in addition to humans. Factors thought to influence emergence of these diseases, including changes in climate and land use, are also believed to underlie the emergence of the rickettsial bacterium Orientia tsutsugamushi, now recognized as a major causative agent of acute encephalitis syndrome in South Asia. In addition, the COVID-19 pandemic has highlighted the role of bats as carriers of viruses. Recent studies have begun to uncover mechanisms by which the immune systems of bats are poised to allow for viral tolerance. Several bat-borne infections, including Nipah virus and Ebola virus, have resulted in recent outbreaks of encephalitis.

SUMMARY

Infectious causes of encephalitis continue to emerge worldwide, in part because of climate change and human impacts on the environment. Expansion of surveillance measures will be critical in rapid diagnosis and limiting of outbreaks in the future.

Seroprevalence of Rickettsial Infections in Northeast India: A Population-Based Cross-Sectional Survey

A cross-sectional survey was undertaken to estimate seroprevalence of immunoglobulin G antibodies against scrub typhus, spotted fever group rickettsiae, and typhus group rickettsiae in randomly selected 48 clusters in 12 districts of 3 Northeast states of India: Assam, Meghalaya, and Tripura. Individuals in 3 age groups (5-8, 9-17, and 18-45 years) were selected from each cluster. Sera (N = 2360) tested were collected as part of a national survey on dengue seroprevalence conducted between September 2017 and February 2018. Overall, seroprevalence of 2.5% was detected against rickettsioses, with highest positivity against spotted fever group rickettsiae, followed by scrub typhus and typhus group rickettsiae. Seroprevalence was highest in Tripura (3.7%), followed by Assam (2.6%) and Meghalaya (1.04%). Adults of 18 to 45 years of age were found to be most affected (3.8%). The study findings indicate the need for increasing testing facilities for active case detection at hospital levels. Efforts on implementing effective preventing strategies are suggested to be targeted in disease-specific endemic foci.

Association of leptospirosis and scrub typhus in acute encephalitis syndrome in a tertiary care hospital in Odisha, India

BACKGROUND

Acute encephalitis syndrome (AES) is a major public health concern in India, causing febrile illness principally associated with viral infection. Bacteria-like scrub typhus and leptospirosis also cause acute febrile illness. Therefore, this study was conceived to address the possible etiological agents contributing to sporadic AES in a tertiary care center in Odisha, India.

METHOD

This was a prospective hospital-based study that enrolled 92 consecutive patients with clinically diagnosed AES whose blood/cerebrospinal fluid samples were tested for IgM antibodies to dengue, Japanese encephalitis (JE), herpes simplex virus (HSV), Epstein-Barr virus (EBV), leptospirosis and scrub typhus.

RESULTS

Viral antibodies to dengue were detected in three (3.26%) cases, HSV1 in four (4.34%) and HSV2 in three (3.26%) cases. Significantly, antibodies to EBV in 22 (23.591%) and to JE in 27 (29.34%) cases were detected. Notably, 30 (32.60%) and 11(12.0%) of patients had IgM antibodies to leptospirosis and scrub typhus, respectively.

CONCLUSION

This observation indicates an association of leptospirosis and scrub typhus infection in sporadic cases of AES, besides other viruses.

Update on prevalence and distribution pattern of tick-borne diseases among humans in India: a review

In the present scenario, tick-borne diseases (TBDs) are well known for their negative impacts on humans as well as animal health in India. The reason lies in their increased incidences due to global warming, environmental and ecological changes, and availability of suitable habitats. On a global basis, they are now considered a serious threat to human as well as livestock health. The major tick-borne diseases in India include Kyasanur forest disease (KFD), Crimean-congo hemorrhagic fever (CCHF), Lyme disease (LD), Q fever (also known as coxiellosis), and Rickettsial infections. In recent years, other tick-borne diseases such as Babesiosis, Ganjam virus (GANV), and Bhanja virus (BHAV) infections have also been reported in India. The purpose of this paper is to review the history and the current state of knowledge of tick-borne diseases in the country. The conclusion of this review is extending the requirement of greater efforts in research and government management for the diagnosis and treatment and as well as prevention of these diseases so that tick-borne disease burden should be minimizing in India.

Impact of cattle on joint dynamics and disease burden of Japanese encephalitis and leptospirosis

Japanese encephalitis (JE) is a mosquito-borne neglected tropical disease. JE is mostly found in rural areas where people usually keep cattle at home for their needs. Cattle in households reduce JE virus infections since they distract vectors and act as a dead-end host for the virus. However, the presence of cattle introduces risk of leptospirosis infections in humans. Leptospirosis is a bacterial disease that spreads through direct or indirect contact of urine of the infected cattle. Thus, cattle have both positive and negative impacts on human disease burden. This study uses a mathematical model to study the joint dynamics of these two diseases in the presence of cattle and to identify the net impact of cattle on the annual disease burden in JE-prevalent areas. Analysis indicates that the presence of cattle helps to reduce the overall disease burden in JE-prevalent areas. However, this reduction is dominated by the vector's feeding pattern. To the best of our knowledge, this is the first study to examine the joint dynamics of JE and leptospirosis.

Neurological facets of scrub typhus: A comprehensive narrative review

Scrub typhus is one of the most frequent causes of acute febrile illness in South and South-east Asian countries. Neurological features accompany 20% of scrub typhus infections, and may affect the central or peripheral nervous system, and sometime, may even occur in combination. Of late, its recognition among clinicians has increased with widening detection of its cutaneous hallmark, called eschar. Multiple mechanisms underlie neurological involvement, including direct invasion (meningitis, encephalitis), vasculitis (myositis) or immune-mediated mechanisms (opsoclonus, myoclonus, optic neuritis, Guillain–Barre syndrome). Despite an immunological basis for several neurological manifestations, response to doxycycline is remarkable, although immune therapy may be necessary for severe involvement. Scientific literature on scrub typhus neurology chiefly emanates from case reports, case series and small studies, and a comprehensive review is warranted to aid clinicians in recognising neurological involvement. This review aims at enriching this gap, and summarises clinical features, laboratory findings, and treatment options for various neurological facets of scrub typhus.

Prediction Rule for Scrub Typhus Meningoencephalitis in Children: Emerging Disease in North India

OBJECTIVES

To evaluate the proportion of scrub typhus meningoencephalitis among children with acute encephalitis syndrome and to outline its differentiating features. To develop a prediction rule for scrub typhus meningoencephalitis.

METHODS

A prospective cohort study was conducted at a tertiary care public hospital in Northern India. Consecutive patients of acute encephalitis syndrome who met our inclusion criteria were enrolled over 2 years. Standardized workup including serum IgM against Orientia tsutsugamushi was performed. Clinical and laboratory features were compared between IgM-positive and IgM-negative patients. The area under the receiver operating characteristic curve of the score derived from "independent predictors" was measured. Sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios were calculated at different cut-offs of the score.

RESULTS

Scrub typhus IgM enzyme-linked immunosorbent assay was positive in 66/352 patients (18.8%). Longer duration of fever and prodromal stage along with eschar, hepatomegaly, lymphadenopathy, and pneumonia were significantly more prevalent in scrub typhus meningoencephalitis. However, petechiae were frequent in non-scrub typhus patients. Leucocytosis, lymphocytosis, thrombocytopenia, hypoalbuminemia, and elevated levels of serum bilirubin, serum transaminases, and cerebrospinal fluid protein were associated with scrub typhus meningoencephalitis. Logistic regression revealed fever for >8 days, pneumonia, absence of petechiae, cerebrospinal fluid protein >1000 mg/L, and serum glutamic oxaloacetic transaminase >100 IU/L as independent "predictors" of scrub typhus meningoencephalitis. The area under the receiver operating characteristic curve (95% confidence interval) of the prediction score was 0.832 (0.78-0.89). Score at cutoff ≥1 had 91% sensitivity, 96.1% negative predictive value, and at cutoff ≥4 had 99.7% specificity, 88.9% positive predictive value, 83.1% negative predictive value, 40.3 positive likelihood ratio, 0.88 negative likelihood ratio for identifying scrub typhus meningoencephalitis.

CONCLUSION

Prediction score may help physicians in peripheral areas to identify and treat scrub typhus meningoencephalitis, an emerging cause of acute encephalitis syndrome in India.

Chronic encephalopathy and locked-in state due to scrub typhus related CNS vasculitis

BACKGROUND

Scrub Typhus, prevalent in Asia-Pacific region, often has neurological manifestations in the setting of acute febrile illness, as acute encephalitis syndrome.

CASE REPORT

A 20-year-old female, from western Rajasthan, India presented with calf pain followed by nausea, vomiting, dizziness, and sequentially progressive weakness of limbs, anarthria and loss of bladder control over 10 days. MRI Brain showed T2-weighted and FLAIR hyperintense lesions in corpus callosum, subcortical and periventricular white matter, basal ganglia, thalamus, brainstem and cerebellum producing starry sky appearance with diffusion restriction. Serum IgM for Scrub typhus was positive and patient progressively improved over 3 weeks with doxycycline.

CONCLUSIONS

This report highlights an unusual presentation of scrub typhus with subacute onset and static course, quadriparesis and locked-in state for 2 months, suspected based on red flags on neuroimaging and reversal of deficits with appropriate treatment.

Seroprevalence & seroincidence of Orientia tsutsugamushi infection in Gorakhpur, Uttar Pradesh, India: A community-based serosurvey during lean (April-May) & epidemic (October-November) periods for acute encephalitis syndrome

Background & objectives

In India, acute encephalitis syndrome (AES) cases are frequently reported from Gorakhpur district in Uttar Pradesh. Scrub typhus is one of the predominant aetiological agents for these cases. In order to delineate the extent of the background of scrub typhus seroprevalence and the associated risk factors at community level, serosurveys during both lean and epidemic periods (phase 1 and phase 2, respectively) of AES outbreaks were conducted in this region.

Methods

Two community-based serosurveys were conducted during lean (April-May 2016) and epidemic AES (October-November 2016) periods. A total of 1085 and 906 individuals were enrolled during lean and epidemic AES periods, respectively, from different villages reporting recent AES cases. Scrub typhus-seronegative individuals (n=254) during the lean period were tested again during the epidemic period to estimate the incidence of scrub typhus.

Results

The seroprevalence of Orientia tsutsugamushi during AES epidemic period [immunoglobulin (Ig) IgG: 70.8%, IgM: 4.4%] was high as compared to that of lean AES period (IgG: 50.6%, P <0.001; IgM: 3.4%). The factors independently associated with O. tsutsugamushi positivity during lean AES period were female gender, illiteracy, not wearing footwear, not taking bath after work whereas increasing age, close contact with animals, source of drinking water and open-air defecation emerged as additional risk factors during the epidemic AES season. IgM positivity was significantly higher among febrile individuals compared to those without fever (7.7 vs. 3.5%, P=0.006). The seroincidence for O. tsutsugamushi was 19.7 per cent, and the subclinical infection rate was 54 per cent.

Interpretation & conclusions

The community-based surveys identified endemicity of O. tsutsugamushi and the associated risk factors in Gorakhpur region. The findings will be helpful for planning appropriate interventional strategies to control scrub typhus.

Scrub typhus - A case series from the state of Sikkim, India

Scrub typhus is one of the leading causes of acute febrile illness in India. It is associated with rash and often an eschar, which responds dramatically to antibiotics. In some cases, it results in serious illness leading to multiple organ involvement and finally death. The various clinical manifestations of scrub typhus arise mainly due to systemic vasculitis, caused by direct effects of organism as well as exaggerated immune response. The disease course is often complicated, leading to mortality in the absence of treatment. Here, in this case series, we describe three cases depicting the typical manifestations which a patient of scrub typhus can present with highlighting the fact that high index of clinical suspicion is of utmost importance for this deadly disease.

An outbreak of Japanese encephalitis in a non-endemic region of north-east India

Background There are few comprehensive reports of epidemic Japanese encephalitis in a previously unaffected region. We report our experience of a first-ever outbreak of it in Sonitpur District, Assam, India, with 45 laboratorycon confirmed cases at a single hospital. Method Between 2 July and 11 August 2008, patients meeting the WHO definition of acute encephalitis syndrome were assessed in a single hospital and had tests including blood and cerebrospinal fluid for Japanese encephalitis antibody titres. Results Ninety-six cases meeting the definition of acute encephalitis syndrome were identified with 45 cases of Japanese encephalitis confirmed by cerebrospinal fluid or blood results. For Japanese encephalitis positive patients, mean age was 36 (range 4-80). Of the 45, 11 (24%) died and a further 21 (47%) had significant residual deficits. Focal neurological signs (40%) and seizures (25%) were common. Conclusion An effective Japanese encephalitis vaccine is the key intervention for limiting the population impact of this disease. Identification of these cases led to a district-wide mass vaccination campaign.

Bioinformatic Exploration of Metal-Binding Proteome of Zoonotic Pathogen Orientia tsutsugamushi

Metal ions are involved in many essential biological processes and are crucial for the survival of all organisms. Identification of metal-binding proteins (MBPs) of human affecting pathogens may provide the blueprint for understanding biological metal usage and their putative roles in pathogenesis. This study is focused on the analysis of MBPs from Orientia tsutsugamushi (Ott), a causal agent of scrub typhus in humans. A total of 321 proteins were predicted as putative MBPs, based on sequence search and three-dimensional structure analysis. Majority of proteins could bind with magnesium, and the order of metal binding was Mg > Ca > Zn > Mn > Fe > Cd > Ni > Co > Cu, respectively. The predicted MBPs were functionally classified into nine broad classes. Among them, gene expression and regulation, metabolism, cell signaling, and transport classes were dominant. It was noted that the putative MBPs were localized in all subcellular compartments of Ott, but majorly found in the cytoplasm. Additionally, it was revealed that out of 321 predicted MBPs 245 proteins were putative bacterial toxins and among them, 98 proteins were nonhomologous to human proteome. Sixty putative MBPs showed the ability to interact with drug or drug-like molecules, which indicate that they may be used as broad-spectrum drug targets. These predicted MBPs from Ott could play vital role(s) in various cellular activities and virulence, hence may serve as plausible therapeutic targets to design metal-based drugs to curtail its infection.

Genetic diversity of Orientia tsutsugamushi strains circulating in Northeast India

Background

Scrub typhus, caused by the intracellular bacteria Orientia tsutsugamushi is widely distributed in Southeast Asian countries with antigenically divergent strains reported across the Asia-Pacific belt. The present study was conducted to characterize the circulating strains of Orientia tsutsugamushi prevailing in two Northeastern states of India-the gateway to most Southeast Asian countries.

Methods

A total of 278 (98 clinical and 180 field collected) scrub typhus positive blood samples collected from December 2014 to December 2016 were subjected for amplification of partial 56 KDa, 47 KDa and 16SrRNA genes of Orientia.

Results

Highest number of PCR positives were obtained for 56 KDa gene (17.3%); followed by 11.2% for 47 KDa gene and 5.1% for 16S rRNA gene. High degree of genetic diversity was identified among the identified strains, especially within the 56 KDa gene. Different strains of Orientia circulate in the northeastern part of India, with a pre-dominance of Karp-like strains. Independently branched isolates formed distinct clades, suggesting the possibility of a new strain type of Orientia.

Conclusion

This study provides insight into the genetic and evolutionary relationship of Orientia strains prevalent in this part of the country. Understanding the regional genetic diversity is crucial for its implications in vaccine developments strategies as well as sero-diagnostics.

Accession numbers

KU163366, KY594249, KY594248, KY594251, KU163359, KU163361, KU163363, KU163369, KY594250, KP067915, KU163373, KU163372, KU163370, KU163364, KU163362, KY594247, KY594252, KU163360, KU163365, KU163367, KU163368, KU163371, KX1555826, KY594257, KY594255, KY594256, KX155825, KX155829, KX155827, KX155828, KY594254, KY594253, KY594258, KY583503, KY583499, KY583501, KY583500, KY583502.

Scrub Typhus Outbreak in Chonburi Province, Central Thailand, 2013

Investigation of a scrub typhus outbreak in Thailand during September 2013 found that 9.1% of Thai soldiers and 11.1% of residents living in areas surrounding training sites had antibodies against the causative agent, Orientia tsutsugamushi. Sequence analysis of O. tsutsugamushi from rodents and chiggers identified 7 genogroups and 3 genotypes.

Scrub typhus strikes back: Are we ready?

Scrub typhus has struck back, albeit with renewed vigour, impacting areas with previously known endemicity as also impressing newer expanses. It is not surprising, therefore, that Scrub typhus has emerged as a leading cause of public health concern globally as well as in India, but are we ready to take on the challenge? Over the last decade, there has been a global increase in the number of outbreaks of Scrub typhus, be it the military occupied areas or the civil population at large. The innumerable outbreaks of Scrub typhus, although disconcerting, have nonetheless contributed phenomenally towards better understanding of the dynamics of scrub typhus. There have been significant contributions to awareness of the disease amongst medical professionals, scrub typhus as a cause of Acute Undifferentiated Febrile Illness (AUFI) and newer clinical manifestation - Acute Encephalitis Syndrome (AES), availability and advances in diagnostics and management, man-vector-pathogen interactions, new records of Leptotrombidium species, newer vectors and Orientia species. Antigenic diversity and the varied clinical presentation of scrub typhus, absence of scrub typhus surveillance system and a lack of political will to recognize the disease as one of the important reemerging public health problem are areas seeking concerted deliberations and actions so that the challenges posed by scrub typhus can be addressed.

Acute Encephalitis Syndrome in Gorakhpur, Uttar Pradesh, 2016: Clinical and Laboratory Findings

BACKGROUND

Seasonal outbreaks of acute encephalitis syndrome (AES) with high fatality have been occurring in Gorakhpur, Uttar Pradesh, India, for several years. We conducted investigations during the 2016 outbreak to identify the etiology.

METHODS

We included 407 hospitalized AES patients with cerebrospinal fluid pleocytosis (>5 cells/mm) in our study. These patients were clinically examined; their blood and cerebrospinal fluid samples were collected and investigated for scrub typhus (ST), Japanese encephalitis virus (JEV), dengue virus and spotted fever group of Rickettsia by serology and/or polymerase chain reaction.

RESULTS

Of the 407 AES patients, 266 (65.4%), 42 (10.3%) and 29 (7.1%) were diagnosed to have ST, JEV and dengue infection, respectively. Four patients were diagnosed to have spotted fever group of Rickettsia infection. A significantly higher proportion of ST patients with AES had hepatomegaly, splenomegaly and facial edema. The common hematologic and biochemical abnormalities among ST-positive patients include thrombocytopenia, raised liver enzymes and bilirubin levels. The case fatality ratio was significantly higher among ST-negative AES patients (36.2% vs. 15.2%; P < 0.05).

CONCLUSIONS

ST accounted for approximately two third of the AES case-patients. Efforts are required to identify the etiology of AES case-patients who are negative for ST, JEV and dengue fever.

Emergence of Orientia tsutsugamushi as an important cause of Acute Encephalitis Syndrome in India

Background

Acute Encephalitis Syndrome (AES) is a major seasonal public health problem in Bihar, India. Despite efforts of the Bihar health department and the Government of India, burden and mortality of AES cases have not decreased, and definitive etiologies for the illness have yet to be identified.

Objectives

The present study was undertaken to study the specific etiology of AES in Bihar.

Methods

Cerebrospinal fluid and/or serum samples from AES patients were collected and tested for various pathogens, including viruses and bacteria by ELISA and/or Real Time PCR.

Findings

Of 540 enrolled patients, 33.3% (180) tested positive for at least one pathogen of which 23.3% were co-positive for more than one pathogen. Most samples were positive for scrub typhus IgM or PCR (25%), followed by IgM positivity for JEV (8.1%), WNV (6.8%), DV (6.1%), and ChikV (4.5%).M. tuberculosis and S. pneumoniae each was detected in ~ 1% cases. H. influenzae, adenovirus, Herpes Simplex Virus -1, enterovirus, and measles virus, each was detected occasionally. The presence of Scrub typhus was confirmed by PCR and sequencing. Bihar strains resembled Gilliam-like strains from Thailand, Combodia and Vietnam.

Conclusion

The highlights of this pilot AES study were detection of an infectious etiology in one third of the AES cases, multiple etiologies, and emergence of O. tsutsugamushi infection as an important causative agent of AES in India.

Acute encephalitis syndrome (AES) is a dreaded disease in India including the state of Bihar. Every year several people specially children, succumb to this disease and often the survivors are left with permanent residual disorders. The present research throws light on specific etiological agents that may cause AES and have found scrub typhus to be an important etiology. Knowing the specific etiology would help in definitive management of the patients that may improve the outcome both in terms of morbidity and mortality, as well as help the policy makers to take specific action for prevention and control of the disease.

Under-diagnosis of rickettsial disease in clinical practice: A systematic review

BACKGROUND

Rickettsial diseases present as acute febrile illnesses, sometimes with inoculation eschars.

METHODS

We performed a systematic review of studies published between 1997 and 2017 to assess the underestimation of non-eschar rickettsial disease (NERD) relative to eschar rickettsial disease (ERD), as a cause of acute fever in patients with rickettsial diseases that commonly present with eschar(s): scrub typhus (ST), Mediterranean spotted fever (MSF), and African tick-bite fever. We compared ERD/NERD ratios according to study design: 'complete approach' studies, with testing performed in all patients with 'unspecified febrile illness'; versus 'clinical judgement' studies, with testing performed if patients presented with specific symptoms.

RESULTS

In 'complete approach' studies, ERD/NERD ratios were significantly lower, suggesting a considerable under-diagnosis of NERD in 'clinical judgement' studies. Based on these results, we estimate that the diagnosis of rickettsial disease was missed in 66.5% of patients with ST, and in 57.9% of patients with MSF.

CONCLUSIONS

Study design influences the reported eschar rates in ST and MSF significantly. NERD is likely to be a vastly underdiagnosed entity, and clinicians should consider and test for the disease more often.

PROSPERO REGISTRATION NUMBER

CRD 42016053348.

Rickettsial Infections and Q Fever Amongst Febrile Patients in Bhutan

There is limited evidence of rickettsial diseases in Bhutan. We explored the contribution of rickettsioses as a cause of undifferentiated febrile illness in patients presenting to 14 Bhutanese hospitals from October 2014 to June 2015. Obvious causes of fever were excluded clinically. Clinico-demographic information and acute blood samples were collected. Samples were tested by immunofluorescence assay (IFA) and qPCR against scrub typhus group (STG), spotted fever group (SFG) and typhus group (TG) rickettsiae, and Q fever (QF). Of the 1044 patients, 539 (51.6%) were female and the mean age was 31.5 years. At least 159 (15.2%) of the patients had evidence of a concurrent rickettsial infection. Of these, 70 (6.7%), 46 (4.4%), 4 (0.4%), and 29 (2.8%) were diagnosed as acute infections with STG, SFG, TG, and QF respectively. Ten (1.0%) patients were seropositive for both SFG and TG. Seven of the 70 STG patients were positive by qPCR. Eschar (p < 0.001), myalgia (p = 0.003), and lymphadenopathy (p = 0.049) were significantly associated with STG, but no specific symptoms were associated with the other infections. Disease incidences were not different between age groups, genders, occupations, and districts, except for students with significantly lower odds of infection with STG (OR = 0.43; 95% CI = 0.20, 0.93; p = 0.031). Rickettsioses were responsible for at least 15% of undifferentiated febrile illnesses in Bhutan, scrub typhus being the commonest. Health authorities should ensure that health services are equipped to manage these infections.

Seroprevalence of rickettsial infections and Q fever in Bhutan

Background

With few studies conducted to date, very little is known about the epidemiology of rickettsioses in Bhutan. Due to two previous outbreaks and increasing clinical cases, scrub typhus is better recognized than other rickettsial infections and Q fever.

Methodology

A descriptive cross-sectional serosurvey was conducted from January to March 2015 in eight districts of Bhutan. Participants were 864 healthy individuals from an urban (30%) and a rural (70%) sampling unit in each of the eight districts. Serum samples were tested by microimmunofluorescence assay for rickettsial antibodies at the Australian Rickettsial Reference Laboratory.

Results

Of the 864 participants, 345 (39.9%) were males and the mean age of participants was 41.1 (range 13–98) years. An overall seroprevalence of 49% against rickettsioses was detected. Seroprevalence was highest against scrub typhus group (STG) (22.6%) followed by spotted fever group (SFG) rickettsia (15.7%), Q fever (QF) (6.9%) and typhus group (TG) rickettsia (3.5%). Evidence of exposure to multiple agents was also noted; the commonest being dual exposure to STG and SFG at 5%. A person’s likelihood of exposure to STG and SFG rickettsia significantly increased with age and farmers were twice as likely to have evidence of STG exposure as other occupations. Trongsa district appeared to be a hotspot for STG exposure while Punakha district had the lowest STG exposure risk. Zhemgang had the lowest exposure risk to SFG rickettsia compared to other districts. People living at altitudes above 2000 meters were relatively protected from STG infections but this was not observed for SFG, TG or QF exposure.

Conclusion

This seroprevalence study highlights the endemicity of STG and SFG rickettsia in Bhutan. The high seroprevalence warrants appropriate public health interventions, such as diagnostic improvements and clinical treatment guidelines. Future studies should focus on vector profiles, geospatial, bio-social and environmental risk assessment and preventive and control strategies.

Rickettsial infections including scrub typhus and Q fever are not widely recognised in Bhutan although the country is situated in an endemic Asian region. With two recorded outbreaks, scrub typhus is known to occur but other rickettsial infections and Q fever have not been recorded. In this first seroprevalence study of rickettsial infections, an overall seroprevalence of 49% was detected against rickettsioses amongst 864 participants. Seroprevalence was highest against scrub typhus group (STG) (22.6%) followed by spotted fever group (SFG) rickettsia (15.7%), Q fever (QF) (6.9%) and typhus group (TG) rickettsia (3.5%). Evidence of exposure to multiple agents were also noted; the commonest being dual exposure to STG and SFG at 5%. A person’s likelihood of exposure to STG and SFG significantly increased with age and farmers were twice as likely to have evidence of STG exposure as other occupations. Trongsa district in central Bhutan appeared to be a hotspot for STG exposure. People living at altitudes above 2000 meters were relatively protected from STG infections but this was not observed for SFG, TG and QF exposure. The findings from this study may direct future research on rickettsioses in Bhutan. These neglected tropical diseases warrant specific public health interventions in Bhutan.