Japanese encephalitis in India: an overview

Seroprevalence of Japanese encephalitis virus in pig populations of Tamil Nadu, India: Exploring the tropical endemic link of virus

Japanese encephalitis virus (JEV) is a major cause of encephalitis in Southeast Asia. Tamil Nadu, a state located in the southern part of India, contributes substantially to the national burden of human JE cases every year. However, limited information is available on the epidemiology of JE in pig populations of Tamil Nadu. A cross-sectional study was conducted to assess JEV prevalence in pig populations of Tamil Nadu. A total of 710 pigs reared in 118 farms across 10 districts of Tamil Nadu were sampled using multistage cluster random sampling. Serum samples were analyzed for their JEV status using Immunoglobulin M (IgM) and Immunoglobulin G (IgG) Enzyme-Linked Immunosorbent Assay (ELISA). At the animal-level, the apparent JEV seroprevalence was 60.4% (95% CI: 56.8% - 64.0%) and the true seroprevalence was 50.1% (95% CI: 47.0% - 53.2%). The herd-level apparent seroprevalence was 94.1% (95% CI: 88.1% - 97.5%) and the true seroprevalence was 93.3% (95% CI: 89.5% - 96.2%). The intensity of JEV circulation was high in all the districts, with seroprevalence ranging between 43% and 100%. Pigs across all age categories were seropositive and a high overall seroprevalence of 95.2% (95% CI: 76.2% - 99.9%) was recorded in pigs older than 12 months. JEV seropositivity was recorded in all the seasons but the prevalence peaked in the monsoon (67.9%, 95% CI: 61.1% - 74.2%) followed by winter (65.1%, 95%CI: 57.4% - 72.2%) and summer (53.3%, 95% CI: 47.8% - 58.8%) seasons. The results indicate that JEV is endemic in pigs populations of the state and a one health approach is essential with collaborative actions from animal and public health authorities to control JE in Tamil Nadu, India.

West Nile virus in India: An update on its genetic lineages

West Nile virus (WNV) is a rapidly spreading mosquito-transmitted zoonotic flavivirus. Mosquitoes belonging to the genus Culex are incriminated as the principal vectors of the virus, which causes West Nile fever (WNF) in humans. Manifestations of WNF include a mild, self-limiting, flu-like illness, which in severe cases (rare) may progress to encephalitis, resulting in life-threatening consequences. WNV is geographically distributed worldwide, covering Africa, the Americas, Europe, and Asia (except Antarctica). The virus exists in a bird-mosquito transmission cycle in nature, with humans and horses as incidental/accidental hosts. The virus can infect a large variety of hosts worldwide, i.e., about 300 birds and around 70 different mosquito species belonging to several genera. For a long time, it was believed that WNV was not highly virulent and caused only mild infection globally. However, the recent frequent and increasing incidence of clinically severe WNV infections, such as encephalitis in humans and horses with significant mortality, has been reported in the Americas, Europe, and several East Asian countries. The emergence of lineage 2 strains endemic to Africa, with epidemic potential in humans and horses in Europe, is considered a serious global health concern. Although WNV is known to circulate in India since 1952, its re-emergence with severe neuro-invasive pathogenic potential in humans in Assam, Kerala, West Bengal and Tamil Nadu states signals urgent efforts to understand the dynamics of circulating strains with regard to its vector, hosts, and environment. This could be done by prioritizing "One Health" approach for developing effective preventive and control strategies. In view of the global interest, we present an overview of the circulating genetic lineages of WNV in India in comparison with the global scenario. In addition, we stress on holistic approaches of "One Health" strategy as the current need of the hour for designing effective preventive and control strategies in the country.

Molecular epidemiology of Japanese encephalitis in pigs and risk factors associated with causing Japanese encephalitis in pigs of Lakhimpur, the first case reported in the district of North East India

BACKGROUND & OBJECTIVES

Japanese encephalitis (JE) is a major public health problem in India. The first outbreaks of JE have been reported from the North-eastern regions of Assam, particularly from the Lakhimpur district of Assam between July-August 1989. In Assam every year many people died due to JE. This study was performed to investigate the molecular epidemiology of JE in pigs in Lakhimpur district of Assam and the risk factors associated with causing Japanese encephalitis in pigs. This study will help to map out the endemic regions and to know where and when to apply the most control strategies towards the prevention and control of the disease.

METHODS

A total of 342 serum samples from pigs were collected from 10 organized and 20 unorganized farms from 9 blocks and recorded to age, sex and breed and tested by RT-PCR. Pig farms and the surrounding environment were studied for assessment of farm-level risk factors responsible for JEV infection in pigs.

RESULTS

Out of 342 samples tested for detection of the E gene of JEV, 14 samples were found to be positive with a prevalence rate of 4.09%. Age, sex and breed-wise higher cases were found in at the age group above 12 months, sex wise female and breed-wise local pigs. Pig farms less than 500 meters from risk factors like rice field, stagnant water source, wild bird exposure to farm and mosquito exposure at farm/ bite to pigs, found to be more numbers of JE cases.

INTERPRETATION & CONCLUSION

Molecular epidemiology of JE in pigs, and humans; positive at Lakhimpur recommend the need for uninterrupted surveillance of this virus in pigs specially those areas where pig population is more and all risk factors are present.

Estimates of Japanese Encephalitis mortality and morbidity: A systematic review and modeling analysis

Background

Japanese Encephalitis (JE) is known for its high case fatality ratio (CFR) and long-term neurological sequelae. Over the years, efforts in JE treatment and control might change the JE fatality risk. However, previous estimates were from 10 years ago, using data from cases in the 10 years before this. Estimating JE disease severity is challenging because data come from countries with different JE surveillance systems, diagnostic methods, and study designs. Without precise and timely JE disease severity estimates, there is continued uncertainty about the JE disease burden and the effect of JE vaccination.

Methodology

We performed a systematic review to collate age-stratified JE fatality and morbidity data. We used a stepwise model selection with BIC as the selection criteria to identify JE CFR drivers. We used stacked regression, to predict country-specific JE CFR from 1961 to 2030. JE morbidity estimates were grouped from similar study designs to estimate the proportion of JE survivors with long-term neurological sequelae.

Principal findings

We included 82 and 50 peer-reviewed journal articles published as of March 06 2021 for JE fatality and morbidity with 22 articles in both analyses. Results suggested overall JE CFR estimates of 26% (95% CI 22, 30) in 1961–1979, 20% (95% CI 17, 24) in 1980–1999, 14% (95% CI 11, 17) in 2000–2018, and 14% (95% CI 11, 17) in 2019–2030. Holding other variables constant, we found that JE fatality risk decreased over time (OR: 0.965; 95% CI: 0.947–0.983). Younger JE cases had a slightly higher JE fatality risk (OR: 1.012; 95% CI: 1.003–1.021). The odds of JE fatality in countries with JE vaccination is 0.802 (90% CI: 0.653–0.994; 95% CI: 0.62–1.033) times lower than the odds in countries without JE vaccination. Ten percentage increase in the percentage of rural population to the total population was associated with 15.35% (95% CI: 7.71, 22.57) decrease in JE fatality odds. Ten percentage increase in population growth rate is associated with 3.71% (90% CI: 0.23, 7.18; 95% CI: -0.4, 8.15) increase in JE fatality odds. Adjusting for the effect of year, rural population percent, age of JE cases, and population growth rate, we estimated that there was a higher odds of JE fatality in India compared to China. (OR: 5.46, 95% CI: 3.61–8.31). Using the prediction model we found that, in 2000–2018, Brunei, Pakistan, and Timor-Leste were predicted to have the highest JE CFR of 20%. Bangladesh, Guam, Pakistan, Philippines, and Vietnam had projected JE CFR over 20% for after 2018, whereas the projected JE CFRs were below 10% in China, Indonesia, Cambodia, Myanmar, Malaysia, and Thailand. For disability, we estimated that 36% (min-max 0–85) JE patients recovered fully at hospital discharge. One year after hospital discharge, 46% (min-max 0%-97%) JE survivors were estimated to live normally but 49% (min-max 3% - 86%)till had neurological sequelae.

Conclusion

JE CFR estimates were lower than 20% after 2000. Our study provides an updated estimation of CFR and proportion of JE cases with long-term neurological sequelae that could help to refine cost-benefit assessment for JE control and elimination programs.

Japanese Encephalitis (JE) is known for its high case fatality ratio (CFR) and long-term neurological sequelae. Although JE fatality and morbidity risk might change as the characteristics of the population change with the strengthened surveillance scales, expanded immunization coverage, and healthcare improvements, there have not been any updates in the estimates for JE mortality and morbidity estimates for 10 years. In this paper, we made updated estimates of the JE CFR and the proportion of JE survivors with long-term neurological sequelae by performing a systematic review and developing statistical and machine learning models. We estimated JE CFR decreased over time, with estimates of 26% (95% CI 22, 30) in 1961–1979, 20% (95% CI 17, 24) in 1980–1999, 14% (95% CI 11, 17) in 2000–2018, and 14% (95% CI 11, 17) in 2019–2030. countries without JE vaccination, younger JE cases, higher population growth rate, and lower rural population percentage were associated with higher JE CFR. We estimated that 36% (min-max 0–85) JE patients recovered fully at hospital discharge. One year after hospital discharge, 46% (min-max 0%-97%) JE survivors were estimated to live normally but 49% (min-max 3% - 86%) JE patients still had neurological sequelae. The insights gained will be important in evaluating and updating current JE disease burden among all endemic areas and effectively channeling resources to most needed areas.

Japanese Encephalitis Virus Infects the Thalamus Early Followed by Sensory-Associated Cortex and Other Parts of the Central and Peripheral Nervous Systems

Japanese encephalitis (JE) is a known CNS viral infection that often involves the thalamus early. To investigate the possible role of sensory peripheral nervous system (PNS) in early neuroinvasion, we developed a left hindlimb footpad-inoculation mouse model to recapitulate human infection by a mosquito bite. A 1-5 days postinfection (dpi) study, demonstrated focal viral antigens/RNA in contralateral thalamic neurons at 3 dpi in 50% of the animals. From 4 to 5 dpi, gradual increase in viral antigens/RNA was observed in bilateral thalami, somatosensory, and piriform cortices, and then the entire CNS. Infection of neuronal bodies and adjacent nerves in dorsal root ganglia (DRGs), trigeminal ganglia, and autonomic ganglia (intestine, etc.) was also observed from 5 dpi. Infection of explant organotypic whole brain slice cultures demonstrated no viral predilection for the thalamus, while DRG and intestinal ganglia organotypic cultures confirmed sensory and autonomic ganglia susceptibility to infection, respectively. Early thalamus and sensory-associated cortex involvement suggest an important role for sensory pathways in neuroinvasion. Our results suggest that JE virus neuronotropism is much more extensive than previously known, and that the sensory PNS and autonomic system are susceptible to infection.

Investigation of Japanese encephalitis virus as a cause of acute encephalitis in southern Pakistan, April 2015-January 2018

Background

Japanese encephalitis (JE) occurs in fewer than 1% of JE virus (JEV) infections, often with catastrophic sequelae including death and neuropsychiatric disability. JEV transmission in Pakistan was documented in 1980s and 1990s, but recent evidence is lacking. Our objective was to investigate JEV as a cause of acute encephalitis in Pakistan.

Methods

Persons aged ≥1 month with possible JE admitted to two acute care hospitals in Karachi, Pakistan from April 2015 to January 2018 were enrolled. Cerebrospinal fluid (CSF) or serum samples were tested for JEV immunoglobulin M (IgM) using the InBios JE Detect^TM assay. Positive or equivocal samples had confirmatory testing using plaque reduction neutralization tests.

Results

Among 227 patients, testing was performed on CSF in 174 (77%) and on serum in 53 (23%) patients. Six of eight patient samples positive or equivocal for JEV IgM had sufficient volume for confirmatory testing. One patient had evidence of recent West Nile virus (WNV) neurologic infection based on CSF testing. One patient each had recent dengue virus (DENV) infection and WNV infection based on serum results. Recent flavivirus infections were identified in two persons, one each based on CSF and serum results. Specific flaviviruses could not be identified due to serologic cross-reactivity. For the sixth person, JEV neutralizing antibodies were confirmed in CSF but there was insufficient volume for further testing.

Conclusions

Hospital-based JE surveillance in Karachi, Pakistan could not confirm or exclude local JEV transmission. Nonetheless, Pakistan remains at risk for JE due to presence of the mosquito vector, amplifying hosts, and rice irrigation. Laboratory surveillance for JE should continue among persons with acute encephalitis. However, in view of serological cross-reactivity, confirmatory testing of JE IgM positive samples at a reference laboratory is essential.

Clinico-epidemiological characteristics of hospitalized acute encephalitis syndrome children and their correlation with case fatality rate

Background:

Acute Encephalitis Syndrome (AES) in children contributes considerable morbidity and mortality in endemic region. A study was conducted to see the clinico-epidemiological characteristics of hospitalized AES children and to find out if there is any correlation of clinico-epidemiological factors with case fatality rate (CFR).

Methods:

This hospital-based observational prospective study was conducted in a tertiary care teaching hospital of Assam, India from 16^th May, 2019 to 15^th May, 2020. We enrolled clinically diagnosed 140 hospitalized AES children consecutively as per WHO case definition. Cerebrospinal fluid and serum samples were tested for JEV-specific IgM antibodies.

Results:

Out of 140 AES children 84 (60%) were male and 5–12 years age group had the highest 79 (56.4%) number of cases. Primarily cases were from rural areas 132 (94.3%). In addition to fever, major clinical manifestations were seizures 114 (81.4%), altered sensorium 128 (91.4%), meningeal signs 62 (44.3%), and <8 GCS 42 (30%). CFR was 27.7%. Significantly high CFR was seen among AES children with GCS <8 (P-value 0.0001) and presence of meningeal signs (P-value 0.0007). A higher proportion of non-survivors 55.6% were non JE AES. Monthly incidence of AES/Death showed a peak in the month of July.

Conclusion:

AES in children is a significant public health problem in the study area with high CFR. Presence of GCS <8 and meningeal irritation are the important predictors of mortality in AES children. Preponderance of non-JE AES case fatality in children warrant further exploration and appropriate public health interventions.

Entomological factors in relation to the occurrence of Japanese encephalitis in Malkangiri district, Odisha State, India

Japanese encephalitis is a mosquito-borne arbo-viral disease with seasonal occurrence. Since 2009, AES/JE cases have been reported from Malkangiri district of Odisha State, India at an interval of one year.In the current study, the entomological parameters of known JE vector mosquito species were assessed for one year in Malkangiri district. Mosquito collections were done fortnightly in the index villages from August 2015 to July 2016 to record the density, their breeding habitats, feeding behaviour, parity, dusk index (DI) and infection status with JE virus. A total of 2347 JE vector mosquitoes belonging to nine species were collected from dusk collections. Culex vishnui (38.3%) was the predominant species followed by Cx. whitmorei (17.3%), Cx. fuscocephalus (13.6%), Cx. tritaeniorhynchus (11.1%), Cx. bitaeniorhynchus (6.1%), Anopheles subpictus (4.8%), An. barbirostris (4.4%), Cx. quinquefasciatus (2.3%) and Cx. gelidus (2.2%). The average DI of Cx. vishnui was 0.37 which was highest among all JE vector species and varied between 0.02 (April) and 0.9 (November). The human blood indexof Cx. vishnui was 0.026. A total of 1835 JE vector mosquitoes were screened for the isolation of JE virus, but none was found positive. Presence of paddy fields and ponds, abundance of JE vectors and their human feeding habit indicate the risk of JE transmission in the study area. Detection of JE virus in Cx. vishnui during 2016 outbreak in Malkangiri district further confirms that there would be a threat of JE transmission during the favourable period.

A descriptive study on prevalence pattern of Japanese encephalitis in State of Manipur

Background and Objective

Japanese encephalitis (JE) surveillance is not well established in many countries, and laboratory confirmation is challenging, the true extent and prevalence of the virus and burden of disease are not well understood. It is estimated that 67,900 clinical cases of JE occur annually despite the widespread availability of vaccine, with approximately 13,600-20,400 deaths and an overall incidence rate of 1.8/100,000 in the 24 countries with JE risk. The present study aimed at determining the prevalence rate (PR) and distribution (time, place and person) of JE cases in Manipur. This descriptive study was conducted over 24-month period (2016-2017).

Materials and Methods

A total of 1770 cases of acute encephalitis syndrome tested for JE including 251 confirmed JE were diagnosed by IgM antibody-capture enzyme-linked immunosorbent assay.

Results

The JE cases were most commonly reported in the age group of >15 years. Most of JE prevalence was seen in rural distribution in our study. There is a strong seasonal pattern of JE occurrence in Manipur which peaked in July-August and declined by October each year, which corresponds to the monsoon season. The JE cases were reported in all the districts of the state expanding in the plains and hill regions.

Conclusions

The changing pattern of JE cases among different age groups was also observed in our study. The present study reveals the changing pattern of the prevalence of JE in the State of Manipur and initiated a systematic approach of JE surveillance also highlights the need for further expanding of surveillance across the state.

Analysis of dengue specific memory B cells, neutralizing antibodies and binding antibodies in healthy adults from India

BACKGROUND

The Indian population is facing highest dengue burden worldwide supporting an urgent need for vaccines. For vaccine introduction, evaluation and interpretation it is important to gain a critical understanding of immune memory induced by natural exposure. However, immune memory to dengue remains poorly characterized in this region.

METHODS

We enumerated levels of dengue specific memory B cells (MBC), neutralizing (NT) and binding antibodies in healthy adults (n=70) from New Delhi.

RESULTS

NT-antibodies, binding antibodies and MBC were detectable in 86%, 86.56% and 81.63% of the subjects respectively. Among the neutralizing positive subjects, 58%, 27%, 5% and 10% neutralized all four, any three, any two and any one dengue serotypes respectively. The presence of the neutralizing antibodies was associated with the presence of the MBC and binding antibodies. However, a massive interindividual variation was observed in the levels of the neutralizing antibodies (range, <1:50-1:30,264), binding antibodies (range, 1:3,000-1:134,000,) as well as the MBC (range=0.006%-5.05%).

CONCLUSION

These results indicate that a vast majority of the adults are immune to multiple dengue serotypes and show massive interindividual variation in neutralizing/binding antibodies and MBCs - emphasizing the importance of monitoring multiple parameters of immune memory in order to properly plan, evaluate and interpret dengue vaccines.

Japanese Encephalitis: A Brief Review on Indian Perspectives

Introduction:

Japanese encephalitis (JE) is recently declared as a notifiable disease in India due to its expanding geographical distribution. The disease notification facilitates effective implementation of preventive measures and case management.

Expalantion:

JE is a vector-borne disease that can be prevented by vaccine administration. It is caused by Japanese encephalitis virus (JEV), belonging to family Flaviviridae. Amongst the known etiological viral encephalitis agents, it is one of the leading viral agents of acute encephalitis syndrome in many Asian countries where it is identified to cause substantial morbidity and mortality as well as disability. Globally, it is responsible for approximately 68,000 clinical cases every year.

Conclusion:

In the absence of antivirals, patients are given supportive treatment to relieve and stabilize. Amongst available control strategies; vector control is resource intensive while animal and human vaccination are the most effective tool against the disease. This review highlights recent progress focusing challenges with diagnosis and prophylactic interventions.

Seroprevalence of Japanese encephalitis virus & West Nile virus in Alappuzha district, Kerala

BACKGROUND & OBJECTIVES

Several outbreaks of acute encephalitis syndrome (AES) have been reported in Alappuzha district, Kerala State, India, in the past. The aetiology of these outbreaks was either inconclusive or concluded as probable Japanese encephalitis virus (JEV) infection based on clinical presentation. The role of West Nile virus (WNV) in AES outbreaks was also determined. However, the extent of WNV infection has not been studied in this region previously. A population-based cross-sectional serosurvey study was undertaken to determine the seroprevalence of JEV and WNV in Alappuzha district.

METHODS

A total of 30 clusters were identified from 12 blocks and five municipalities as per the probability proportional to size sampling method. A total of 1125 samples were collected from all age groups. A microneutralization assay was performed to estimate the prevalence of JEV and WNV neutralizing antibodies in the sample population.

RESULTS

Of 1125 serum samples tested, 235 [21.5%, 95% confidence interval (CI): 15.2-27.8%] and 179 (15.9%, 95% CI: 9.6-22.3%) were positive for neutralizing antibodies against WNV and JEV, respectively. In addition, 411 (34.5%, 95% CI: 26.7-42.2%) were positive for cross-reactive antibodies against flaviviruses.

INTERPRETATION & CONCLUSIONS

The study showed the seroprevalence of WNV and JEV antibodies in the surveyed area and the WNV seroprevalence was greater than JEV. It is necessary to create awareness in public and adopt suitable policy to control these diseases.

Epidemiological Profile of Acute Viral Encephalitis

OBJECTIVE

To study the etiology and clinico-epidemiological profile of acute viral encephalitis in children with acute encephalitis syndrome (AES).

METHODS

An observational study including 100 patients fulfilling the criteria for AES was conducted in children of age group 1 mo - 16 y. Viral isolation was done on RD cells, HEp-2 cells and Vero cells from the cerebrospinal fluid samples of suspected viral encephalitis (VE) cases. An enzyme immunoassay for IgM antibodies was performed for measles, mumps, Varicella zoster virus (VZV), Herpes simplex virus 1 (HSV1) and Japanese encephalitis virus (JEV). Multiplex polymerase chain reaction (PCR) was done for Cytomegalovirus, Epstein Barr virus (EBV), HSV1 & 2, VZV, Enterovirus, Parecho virus, Human Herpes virus (HHV 6, 7) and Parvovirus B19. A micro neutralization test was performed for Enterovirus 71.

RESULTS

Out of enrolled 100 patients, 73 were of probable viral encephalitis. HSV1 (31.50%) was the commonest virus followed by Adenovirus (10.95%), Parvovirus (2.73%), JE virus (1.36%), Enterovirus (1.36%), EBV (1.36%), and mixed infection with HSV & EBV (1.36%). HSV 1 caused significant morbidity in children. The common computed tomography (CT) findings were hypodensities in the fronto- parietal lobe followed by cerebral edema.

CONCLUSIONS

The landscape of AES in India has changed in the previous decade, and both outbreak investigations and surveillance studies have increasingly reported non-JEV etiologies; because of these findings there is a need to explore additional strategies to prevent AES beyond vector control and JEV vaccination.

Aetiological study of viruses causing acute encephalitis syndrome in North West India

CONTEXT

Acute encephalitis syndrome (AES) is a serious public health problem, caused mainly by viruses. However, the profile of viruses causing AES in Rajasthan is not well characterised.

AIMS

The present study was undertaken to identify the viruses causing AES and develop diagnostic algorithm so as to help in improved diagnosis, treatment, prevention and control.

SETTINGS AND DESIGN

The present study is a hospital-based descriptive, observational study. Samples were processed at Grade-1 DHR/ICMR Viral Research and Diagnostic Laboratory at SMS, Jaipur.

SUBJECTS AND METHODS

Cerebrospinal fluid (CSF) samples were processed for IgM antibody detection by enzyme-linked immunosorbent assay (ELISA) for mumps virus (MPV), measles virus (MV), Rubella virus (RV), Japanese encephalitis virus (JEV), West Nile virus (WNV) and Dengue virus using commercial kits. Nucleic acid was extracted from CSF using automated extraction system. Real-time polymerase chain reaction was done using specific primers and probes for Herpes simplex virus (HSV), Varicella-zoster virus (VZV), Epstein-Barr virus (EBV), cytomegalovirus (CMV) and enterovirus (EV).

STATISTICAL ANALYSIS USED

Statistical analysis was done using ANOVA.

RESULTS

Among 3088 patients, 702 (22.7%) patients were positive for one or more viruses. HSV (261;8.45%) was the most common followed by EBV (173;5.6%), VZV (97;3.1%), CMV (68;2.2%), EV (32;1.03%), MPV (27;0.9%), DV (28;0.9%), MV (19;0.6%) and RV (6;0.2%).

CONCLUSIONS

AES occurred sporadically in Rajasthan, samples should be tested first for herpes group of viruses followed by EV or/and for arboviruses depending on season or measles, mumps and RVs in children.

Immunogenicity & safety of a single dose of live-attenuated Japanese encephalitis vaccine SA 14-14-2 in adults

Background & objectives:

Japanese encephalitis (JE) caused by mosquito-borne Flavivirus is one of the leading causes of viral encephalitis in Asia. Control strategies include vector control and human vaccination. Due to lack of immunization programmes in endemic regions, there are still high mortality and morbidity. A live-attenuated SA 14-14-2 JE vaccine (LAJEV) has been licensed and used in Asian countries, including India. We report the assessment of immunogenicity and safety of the vaccine in adults during the first mass adult vaccination campaign carried out in Assam, India.

Methods:

One thousand and seventy five adults (aged ≥15 yr) who received LAJEV were monitored for adverse events following immunization for one year. The safety assessment of vaccinated population was evaluated till 28 days and at 6 and 12 months. Blood samples collected from the enrolled participants were tested by plaque reduction neutralization test (PRNT₅₀) to assess the neutralizing antibody titres (NATs) before vaccination and 28 days, six and 12 months post-vaccination (PV).

Results:

Among the 1075 vaccinated individuals, four reported minor adverse effects from 30 min to 28 days PV. Based on the pre-vaccination NAT, the study participants were categorized as seronegative, moderately seropositive and strongly seropositive. Nearly 85.5 per cent of JE seronegative participants seroconverted by 28 days PV. The geometric mean titre (GMT) in all the three groups increased by 28 days and decreased by six and 12 months PV. Nearly 60 per cent of the moderately positive individuals exhibited four-fold rise in GMT, 28 days PV. Almost 95.5 per cent of the participants in the study population remained seroprotected at the end of 12 months PV.

Interpretation & conclusions:

This study on immunogenicity and safety of LAJEV in adults showed that a single dose of the live-attenuated vaccine was safe and induced protective immunity to both JE seronegative and naturally seropositive adults. Further study is required to find out long term protective efficacy of this vaccine.

Seasonal abundance & role of predominant Japanese encephalitis vectors Culex tritaeniorhynchus & Cx. gelidus Theobald in Cuddalore district, Tamil Nadu

Background & objectives:

Japanese encephalitis (JE) is the leading cause of viral encephalitis in Asia. The first major JE outbreak occurred in 1978 and since 1981 several outbreaks had been reported in the Cuddalore district (erstwhile South Arcot), Tamil Nadu, India. Entomological monitoring was carried out during January 2010 - March 2013, to determine the seasonal abundance and transmission dynamics of the vectors of JE virus, with emphasis on the role of Culex tritaeniorhynchus and Cx. gelidus.

Methods:

Mosquito collections were carried out fortnightly during dusk hours in three villages viz. Soundara Solapuram, Pennadam, Erappavur of Cuddalore district. Mosquitoes were collected during dusk for a period of one hour in and around the cattle sheds using oral aspirator and torch light. The collected mosquitoes were later identified and pooled to detect JE virus (JEV) infection by enzyme linked immunosorbent assay (ELISA).

Results:

A total of 46,343 mosquitoes comprising of 25 species and six genera were collected. Species composition included viz, Cx. tritaeniorhynchus (46.26%), Cx. gelidus (43.12%) and other species (10.62%). A total of 17,678 specimens (403 pools) of Cx. gelidus and 14,358 specimens (309 pools) of Cx. tritaeniorhynchus were tested, of which 12 pools of Cx. gelidus and 14 pools of Cx. tritaeniorhynchus were positive for JE virus antigen. The climatic factors were negatively correlated with minimum infection rate (MIR) for both the species, except mean temperature (P<0.05) for Cx. gelidus.

Interpretation & conclusions:

High abundance of Cx. tritaeniorhynchus and Cx. gelidus was observed compared to other mosquito species in the study area. Detection of JEV antigen in the two species confirmed the maintenance of virus. Appropriate vector control measures need to be taken to reduce the vector abundance.

Apoptosis, autophagy and unfolded protein response pathways in Arbovirus replication and pathogenesis

Arboviruses are pathogens that widely affect the health of people in different communities around the world. Recently, a few successful approaches toward production of effective vaccines against some of these pathogens have been developed, but treatment and prevention of the resulting diseases remain a major health and research concern. The arbovirus infection and replication processes are complex, and many factors are involved in their regulation. Apoptosis, autophagy and the unfolded protein response (UPR) are three mechanisms that are involved in pathogenesis of many viruses. In this review, we focus on the importance of these pathways in the arbovirus replication and infection processes. We provide a brief introduction on how apoptosis, autophagy and the UPR are initiated and regulated, and then discuss the involvement of these pathways in regulation of arbovirus pathogenesis.

Phylogeographic analysis of Japanese encephalitis virus in India (1956-2012)

Japanese encephalitis virus (JEV) isolates from India phylogenetically belong to two genotypes, III and I. We used envelope gene sequences from GenBank, representing different states of India and other countries, to study the spatiotemporal transmission histories of these two JEV genotypes separately. Genotype III was found to have been successively introduced in the 1930s, 1950s and 1960s, followed by genotype I twice around 2003-2006. Changes in JEV disease patterns in India over the last five decades could thus be attributed to multiple introductions of JEV strains from neighboring Asian countries along with increased transmission potential due to altered ecological settings.

Trend of Japanese encephalitis in Uttar Pradesh, India from 2011 to 2013

As indicated by the sporadic Japanese encephalitis (JE) cases reported from the districts of Uttar Pradesh (UP), India, the disease is endemic in the state despite the fact that a JE vaccination programme has been ongoing in the state since 2006. Hence, the present study was undertaken to study the annual trend of JE in UP during January 2011 to December 2013. CSF and/or serum samples collected from acute encephalitis syndrome (AES) cases were referred to the virology laboratory at King George's Medical University, Lucknow and were tested for anti-JEV IgM antibodies by JEV MAC-ELISA kit. The study reveals that 26·9%, 9·9% and 14·8% of AES cases were positive for anti-JEV IgM in the years 2011, 2012 and 2013, respectively. Of the total JE confirmed cases, 30% were adults. Males were more commonly affected than females. A distinct peak of JE was seen in the monsoon and post-monsoon season, although sporadic cases were also reported in other months. JE vaccination by district in UP is discussed. This study reports that the proportion of JE positives in AES cases is decreasing in UP although the number of AES cases has not decreased. The study also discusses the probable causes of this decrease, including JE vaccination and natural periodicity due to herd immunity.

Mass scale screening of common arboviral infections by an affordable, cost effective RT-PCR method

OBJECTIVE

To develop a rapid, cost effective RT-PCR method for the mass scale diagnosis of such diseases at the viremia stage to find out the actual disease burden in that area.

METHODS

For this purpose, cases with the history of only short febrile illness were considered. Thus 157 samples with the history of dengue/chikungunya like illness and only 58 samples with a history of acute encephalitis syndrome (AES) were selected.

RESULTS

Out of 157 samples, 42 and 74 were detected as dengue and chikungunya, respectively and out of 58 AES cases only 23 could be detected as Japanese encephalitis by this RT-PCR method.

CONCLUSIONS

This cost effective RT-PCR method can detect the total positive cases that remain undetected by ELISA method. Moreover, this method is capable to detect the viral RNA from patients' sera even after the appearance of IgM antibody at one fifth costs as compared with the other commercially available kits.

Epidemiology of Japanese encephalitis: past, present, and future prospects

Japanese encephalitis (JE) is one of severe viral encephalitis that affects individuals in Asia, western Pacific countries, and northern Australia. Although 67,900 JE cases have been estimated among 24 JE epidemic countries annually, only 10,426 have been reported in 2011. With the establishment of JE surveillance and vaccine use in some countries, the JE incidence rate has decreased; however, serious outbreaks still occur. Understanding JE epidemics and identifying the circulating JE virus genotypes will improve JE prevention and control. This review summarizes the current epidemiology data in these countries.

A Japanese Encephalitis Vaccine From India Induces Durable and Cross-protective Immunity Against Temporally and Spatially Wide-ranging Global Field Strains

BACKGROUND

Japanese encephalitis (JE) is a vaccine-preventable acute disease. We report the results of a phase 2/3 trial of JENVAC, a Vero cell-derived vaccine developed using an Indian strain of JE virus (JEV).

METHODS

JENVAC was administered in 2 doses 28 days apart, and immunogenicity was compared to that from a single dose of SA-14-14-2, the only approved JE vaccine and regimen at the time in India.

RESULTS

After both the doses, seroconversion and seroprotection were >90% for JENVAC. For SA-14-14-2, seroconversion and seroprotection were 57.69% and 77.56%, respectively, on day 28 and 39.74% and 60.26%, respectively, on day 56. The geometric mean titers at day 28 and day 56 were 145.04 and 460.53, respectively, for JENVAC and 38.56 and 25.29, respectively, for SA-14-14-2. With a single dose of JENVAC, seroprotection titers lasted at least 12 months in >80% of the subjects. Following receipt of 2 doses, 61.17% of subjects retained seroprotection titers at 24 months, and immunogenicity criteria were higher than that for SA-14-14-2 at 12, 18, and 24 months each. Sera from JENVAC subjects neutralized JEV genotypes I, II, III, and IV equally well. Adverse events were not significantly different between the 2 vaccines.

CONCLUSIONS

JENVAC elicits long-lasting, broadly protective immunity.

CLINICAL TRIALS REGISTRATION

CTRI/2011/07/001855.

Mosquito surveillance revealed lagged effects of mosquito abundance on mosquito-borne disease transmission: a retrospective study in Zhejiang, China

Mosquito-borne diseases (MBDs) are still threats to public health in Zhejiang. In this study, the associations between the time-lagged mosquito capture data and MBDs incidence over five years were used to examine the potential effects of mosquito abundance on patterns of MBDs epidemiology in Zhejiang during 2008–2012. Light traps were used to collect adult mosquitoes at 11 cities. Correlation tests with and without time lag were performed to investigate the correlations between MBDs incidence rates and mosquito abundance by month. Selected MBDs consisted of Japanese encephalitis (JE), dengue fever (DF) and malaria. A Poisson regression analysis was performed by using a generalized estimating equations (GEE) approach, and the most parsimonious model was selected based on the quasi-likelihood based information criterion (QICu). We identified five mosquito species and the constituent ratio of Culex pipiens pallens, Culex tritaeniorhynchus, Aedes albopictus, Anopheles sinensis and Armigeres subalbatus was 66.73%, 21.47%, 6.72%, 2.83% and 2.25%, respectively. The correlation analysis without and with time lag showed that Culex mosquito abundance at a lag of 0 or 1 month was positively correlated with JE incidence during 2008–2012, Ae. albopictus abundance at a lag of 1 month was positively correlated with DF incidence in 2009, and An. sinensis abundance at a lag of 0–2 months was positively correlated with malaria incidence during 2008–2010. The Poisson regression analysis showed each 0.1 rise of monthly mosquito abundance corresponded to a positive increase of MBD cases for the period of 2008–2012. The rise of mosquito abundance with a lag of 0–2 months increased the risk of human MBDs infection in Zhejiang. Our study provides evidence that mosquito monitoring could be a useful early warning tool for the occurrence and transmission of MBDs.

Biomarkers in Japanese encephalitis: a review

JE is a flavivirus generated dreadful CNS disease which causes high mortality in various pediatric groups. JE disease is currently diagnosed by measuring the level of viral antigens and virus neutralization IgM antibodies in blood serum and CSF by ELISA. However, it is not possible to measure various disease-identifying molecules, structural and molecular changes occurred in tissues, and cells by using such routine methods. However, few important biomarkers such as cerebrospinal fluid, plasma, neuro-imaging, brain mapping, immunotyping, expression of nonstructural viral proteins, systematic mRNA profiling, DNA and protein microarrays, active caspase-3 activity, reactive oxygen species and reactive nitrogen species, levels of stress-associated signaling molecules, and proinflammatory cytokines could be used to confirm the disease at an earlier stage. These biomarkers may also help to diagnose mutant based environment specific alterations in JEV genotypes causing high pathogenesis and have immense future applications in diagnostics. There is an utmost need for the development of new more authentic, appropriate, and reliable physiological, immunological, biochemical, biophysical, molecular, and therapeutic biomarkers to confirm the disease well in time to start the clinical aid to the patients. Hence, the present review aims to discuss new emerging biomarkers that could facilitate more authentic and fast diagnosis of JE disease and its related disorders in the future.

Infection of human endothelial cells by Japanese encephalitis virus: increased expression and release of soluble HLA-E

Japanese encephalitis virus (JEV) is a single stranded RNA virus that infects the central nervous system leading to acute encephalitis in children. Alterations in brain endothelial cells have been shown to precede the entry of this flavivirus into the brain, but infection of endothelial cells by JEV and their consequences are still unclear. Productive JEV infection was established in human endothelial cells leading to IFN-β and TNF-α production. The MHC genes for HLA-A, -B, -C and HLA-E antigens were upregulated in human brain microvascular endothelial cells, the endothelial-like cell line, ECV 304 and human foreskin fibroblasts upon JEV infection. We also report the release/shedding of soluble HLA-E (sHLA-E) from JEV infected human endothelial cells for the first time. This shedding of sHLA-E was blocked by an inhibitor of matrix metalloproteinases (MMP). In addition, MMP-9, a known mediator of HLA solubilisation was upregulated by JEV. In contrast, human fibroblasts showed only upregulation of cell-surface HLA-E. Addition of UV inactivated JEV-infected cell culture supernatants stimulated shedding of sHLA-E from uninfected ECV cells indicating a role for soluble factors/cytokines in the shedding process. Antibody mediated neutralization of TNF-α as well as IFNAR receptor together not only resulted in inhibition of sHLA-E shedding from uninfected cells, it also inhibited HLA-E and MMP-9 gene expression in JEV-infected cells. Shedding of sHLA-E was also observed with purified TNF-α and IFN-β as well as the dsRNA analog, poly (I:C). Both IFN-β and TNF-α further potentiated the shedding when added together. The role of soluble MHC antigens in JEV infection is hitherto unknown and therefore needs further investigation.

Envelope protein gene based molecular characterization of Japanese encephalitis virus clinical isolates from West Bengal, India: a comparative approach with respect to SA14-14-2 live attenuated vaccine strain

Background

Increasing virulence of Japanese encephalitis virus (JEV), a mosquito-borne zoonotic pathogen is of grave concern because it causes a neurotrophic killer disease Japanese Encephalitis (JE) which, in turn, is responsible globally for viral acute encephalitis syndrome (AES). Despite the availability of vaccine, JE/AES cases and deaths have become regular features in the different rural districts of West Bengal (WB) state, India, indicating either the partial coverage of vaccine or the emergence of new strain of JEV. Therefore, a study was undertaken to characterize and compare the complete envelope (E) protein gene based molecular changes/patterns of JEVs circulating in WB.

Methods

Total of 98 AES case-patients’ samples were tested to detect the presence of JEV specific immunoglobulin M (IgM) antibody by Mac-ELISA method. Only JEV IgM negative samples with a history of ≤3 days’ illness were screened for virus isolation and RT-PCR. E gene sequences of JEV isolates were subjected to molecular phylogeny and immunoinformatics analysis.

Results

Present study confirmed JEV etiology in 39.7% and 29.1% of patients presenting ≤15 days’ febrile illness, as determined by Mac-ELISA and RT-PCR respectively. Phylogenetic analysis based on complete E gene sequences of JEV isolates showed the co-circulation of JEV genotype I (GI) with genotype III (GIII). This study also demonstrated that isolate-specific crucial amino acid substitutions were closely related to neurovirulence/neuroinvasiveness of JE. On the basis of immunoinformatics analysis, some substitutions were predicted to disrupt T-cell epitope immunogenicity/antigenicity that might largely influence the outcome of vaccine derived from JEV GIII SA14-14-2 strain and this has been observed in a previously vaccinated boy with mild JE/AES due to JEV GI infection.

Conclusions

Based on molecular evolutionary and bioinformatic approaches, we report evolution of JEV at a local level. Such naturally occurring evolution is likely to affect the disease profile and the vaccine efficacy to protect against JEV GI may demand careful evaluation.

Association of weather and anthropogenic factors for transmission of Japanese encephalitis in an endemic area of India

Weather and anthropogenic factors are important determinants for Japanese encephalitis (JE) transmission. During 2008-2010, an increasing trend of JE was observed in Dibrugarh district of Northeast India. The JE cases were found to be clustered between June to October in each year. Monthly minimum temperature and rainfall were significantly associated with JE transmission at 1 and 2 months lagged. However, the relationship was more prominent at a lag of 1 month than that of two. Regression analysis suggested that rainfall, minimum and maximum temperature, and relative humidity at 6:00 h are significant predictors (P < 0.05) of quarterly occurrence of JE cases. Additional anthropogenic risk factors including the conditions such as pig sty/cattle shed around and lower part of the houses and proximity of rice field to the dwelling houses (P < 0.05) were also found to be predictors for JE occurrence. Meteorological and anthropogenic risk factors can be used to forecast JE outbreaks in Assam which in turn can help the local health authorities to protect communities in JE prone areas.

Japanese encephalitis: a review of the Indian perspective

Japanese encephalitis virus (JEV) causes Japanese encephalitis, which is a leading form of viral encephalitis in Asia, with around 50,000 cases and 10,000 deaths per year in children below 15 years of age. The JEV has shown a tendency to extend to other geographic regions. Case fatality averages 30% and a high percentage of the survivors are left with permanent neuropsychiatric sequelae. Currently, there is no cure for JEV, and treatment is mainly supportive. Patients are not infectious, but should avoid further mosquito bites. A number of antiviral agents have been investigated; however, none of these have convincingly been shown to improve the outcome of JEV. In this review, the current knowledge of the epidemiology and the pathogenesis of this deadly disease have been summarized.

Complete genome sequence analysis of Japanese encephalitis virus isolated from a horse in India

The complete genome of the Japanese encephalitis virus (JEV) strain JEV/eq/India/H225/2009(H225), isolated from an infected horse in India, was sequenced and compared to previously published JEV genomes. H225 genome was 10,977-nucleotides long, comprising a single ORF of 10,299-nucleotides, a 5'-UTR of 95 nucleotides and a 3'-UTR of 582 nucleotides. The H225 genome showed high levels of sequence identity with 47 fully sequenced JEV genomes, ranging from 99.3 % to 75.5 % for nucleotides and 99.2 % to 91.5 % for amino acid sequences. Phylogenetic analysis of the full-length sequence indicated that the H225 strain belongs to genotype III and is closely related to the Indian JEV strain Vellore P20778. A comparison of amino acids associated with neurovirulence in the E proteins and non-structural proteins of known virulent and attenuated JEV strains suggested H225 to be a highly virulent strain. This is the first report of whole-genome sequencing of a genotype III JEV genome isolated from equines.

Changing clinico-laboratory profile of encephalitis patients in the eastern Uttar Pradesh region of India

A cross-sectional study was done on 100 consecutive paediatric patients presenting with acute encephalitis syndrome. The clinico-laboratory features of all patients were recorded in a prestructured performa. Cerebrospinal fluid and serum samples were tested for: Japanese encephalitis (JE) virus; Chandipura virus; coxsackie virus; dengue virus; enterovirus 76; and West Nile virus. Twenty-two (22.0%) patients were confirmed JE cases and 17% had parasitic or bacteriological aetiology. The remaining 61 cases (61.0%) in which no viral aetiological agent was found were grouped as non-JE cases. Peripheral vascular failure, splenomegaly and hypotonia were distinguishing clinical features found in the non-JE patients. A high mortality of 26.5% was seen in patients with confirmed or presumptive viral encephalitis (22/83). A fatal outcome was independently associated with peripheral vascular failure and pallor at the time of admission. Early recognition of these signs may help clinicians to manage these cases.

Impact of weather variables on mosquitoes infected with Japanese encephalitis virus in Kurnool district, Andhra Pradesh

OBJECTIVE

To assess the virus infection in mosquitoes during different seasons and correlated with various climatic factors.

METHODS

The field collected vectors were screened for Japanese encephalitis (JE) virus after dessication using ELISA method. Most of the positive pools were recorded from Culex tritaeniorhynchus (Cx. tritaeniorhynchus) and Culex. gelidus (Cx. gelidus) during JE transmission season (winter) and some positive pools were also reported during non JE transmission periods (i.e. summer and rainy seasons).

RESULTS

The minimum infection rates (MIR) of 1.75 from Cx. tritaeniorhynchus and 0.17 from Cx. gelidus has been reported in the year 2002 at the beginning of the study and the values were found nil at the end of the study (2006) from the study areas of Kurnool district.

CONCLUSIONS

From this study it is noted that MIR of Cx. gelidus and Cx. tritaeniorhynchus were modulated by various meteorological parameters. The mosquito vector abundance increases after the monsoon period (winter) and lowest in dry season (summer). Similarly, MIR fluctuated between seasons with higher MIR recorded after monsoon period and lower in the rest of season. Impact of these metrological parameters in JE virus infected mosquitoes is discussed in this paper.

Epidemiological concordance of Japanese encephalitis virus infection among mosquito vectors, amplifying hosts and humans in India

A temporal relationship of Japanese encephalitis virus (JEV) transmission in pigs, mosquitoes and humans revealed that sentinel pig seroconversions were significantly associated with human cases 4 weeks before (P = 0·04) their occurrence, highly correlated during the same time and 2 weeks before case occurrence (P < 0·001), and remained significantly correlated up to 2 weeks after human case occurrence (P < 0·01). JEV was detected in the same month in pigs and mosquitoes, and peaks of pig seroconversion were preceded by 1-2 months of peaks of infection in vectors. Kaplan-Meier analysis indicated that detection of JEV-positive mosquitoes was significantly associated with the median time to occurrence of seroconversion in pigs (P < 0·05). This study will not only help in predicting JEV activity but also accelerate timely vector control measures and vaccination programmes for pigs and humans to reduce the Japanese encephalitis risk in endemic areas.

Serological and molecular diagnosis of Japanese encephalitis reveals an increasing public health problem in the state of West Bengal, India

Japanese encephalitis (JE), a neurotrophic disease, was first recorded in the state of West Bengal, India in 1973. Since then JE is being reported every year from different districts. With a view to identify the JE cases accurately, a study was undertaken to detect the Japanese encephalitis virus (JEV) as the etiologic agent from the acute encephalitis syndrome (AES) cases and to identify its distribution in different districts. We report the results of 513 blood or cerebrospinal fluid samples referred/collected from the hospitalized AES cases. The samples were initially subjected to Mac-ELISA test followed by reverse transcriptase (RT)-PCR for the detection of IgM antibodies and the JEV genome, specific to E gene, respectively. Out of 513 samples referred/collected, 139 (27.1%) samples were reactive to JE IgM antibody. The remaining 374 samples were screened to select those which had a history of illness with a duration of ≤3 days. Only 147 samples were selected and tested, out of which 36 (24.5%) isolates were achieved and those were RT-PCR positive against the control JEV strain. Detection of IgM antibody to JE and the RT-PCR result confirms the active circulation of JEV in different districts of West Bengal and needs to be monitored carefully.

A novel low-cost approach to estimate the incidence of Japanese encephalitis in the catchment area of three hospitals in Bangladesh

Acute meningoencephalitis syndrome surveillance was initiated in three medical college hospitals in Bangladesh in October 2007 to identify Japanese encephalitis (JE) cases. We estimated the population-based incidence of JE in the three hospitals' catchment areas by adjusting the hospital-based crude incidence of JE by the proportion of catchment area meningoencephalitis cases who were admitted to surveillance hospitals. Instead of a traditional house-to-house survey, which is expensive for a disease with low frequency, we attempted a novel approach to identify meningoencephalitis cases in the hospital catchment area through social networks among the community residents. The estimated JE incidence was 2.7/100,000 population in Rajshahi (95% confidence interval [CI] = 1.8-4.9), 1.4 in Khulna (95% CI = 0.9-4.1), and 0.6 in Chittagong (95% CI = 0.4-0.9). Bangladesh should consider a pilot project to introduce JE vaccine in high-incidence areas.

Pathology of acute henipavirus infection in humans and animals

Zoonoses as causes of human infections have been increasingly reported, and many of these are viruses that cause central nervous system infections. This paper focuses on the henipaviruses (family Paramyxoviridae, genus henipavirus) that have recently emerged to cause severe encephalitis and systemic infection in humans and animals in the Asia-Pacific region. The pathological features in the human infections comprise vasculopathy (vasculitis, endothelial multinucleated syncytia, thrombosis, etc.) and parenchymal cell infection in the central nervous system, lung, kidney, and other major organs. Most animals naturally or experimentally infected show more or less similar features confirming the dual pathogenetic mechanism of vasculopathy-associated microinfarction and direct extravascular parenchymal cell infection as causes of tissue injury. The most promising animal models include the hamster, ferret, squirrel monkey, and African green monkey. With increasing evidence of infection in the natural hosts, the pteropid bats and, hence, probable future outbreaks in many more countries, a greater awareness of henipavirus infection in both humans and animals is imperative.

Japanese encephalitis (JE). Part I: clinical profile of 1,282 adult acute cases of four epidemics

Japanese encephalitis (JE) is numerically the most important global cause of encephalitis and so far confirmed to have caused major epidemics in India. Most of the reported studies have been in children. This largest study involving only adults, belonging to four epidemics, is being reported from Gorakhpur. The aim of this study is to detail the acute clinical profile (not viral) outcome and to classify the sequelae at discharge. This prospective study involved 1,282 adult patients initially diagnosed as JE admitted during the epidemics of 1978, 1980, 1988, and 1989, on identical clinical presentation and CSF examination. In the meantime, the diagnosis of JE was confirmed by serological and/or virological studies in only a representative number of samples (649 of 1,282 cases). Eighty-three left against medical advice (LAMA) at various stages, so 1,199 of 1,282 were available for the study. Peak incidence of [1,061 of 1,282 (83%)] of clinically suspected cases was from September 15 to November 2. Serum IgM and IgG were positive in high titers in 50.87% (330 of 649) and IgM positive in CSF in 88.75% (109 of 123) of the cases. JE virus could be isolated from CSF and brain tissue in 5 of 5 and 4 of 5 samples, respectively. Altered sensorium (AS) in (96%), convulsions (86%), and headache (85%) were the main symptoms for hospitalization by the third day of the onset. Other neurological features included hyperkinetic movements in 593 of 1,282 (46%)-choreoathetoid in 490 (83%) and bizarre, ill-defined in 103 (17%). The features of brain stem involvement consisted of opsoclonus (20%), gaze palsies (16%), and pupillary changes (48%) with waxing and waning character. Cerebellar signs were distinctly absent. Dystonia and decerebrate rigidity was observed in 43 and 6%, respectively, paralytic features in 17% and seizures in 30%. Many non-neurological features of prognostic importance included abnormal breathing patterns (ABP) (45%), pulmonary edema (PO) (33%), and upper gastrointestinal hemorrhage (UGIH) (16%). Injection dexamethasone was used in 1978 in all 208 cases, including 21 of PO. Patients were later randomized alternately in dexa and non-dexa groups. Forty-six cases of PO from the non-dexa group were transferred to the dexa group as an ultimate life-saving measure. Thus, it was administered in 737 of 1,199 patients including 529 patients from the later epidemics in doses of 4 mg IV every 8 h for 7 days. Of 1,199, 462 did not receive it. There was no significant difference in mortality (p > 0.05) between the dexa (42.47%) and the non-dexa group (42.86%). All PO cases expired; so after the exclusion of the PO cases from dexa group, the difference of 6.14% (42.86 and 36.72) became significant (p < 0.01) (511 of 1,199 (43%) expired, [320 of 511 (63%) died within 3 days of hospitalization]). Out of a total of 1,199 patients treated, 688 (57%) were discharged; 23 of 688 (3%) without any sequelae and 665 of 688 (97%) with neuropsychiatric deficits classified into nine groups. During the four epidemics, the diagnosis of JE was basically on identical clinical presentation of acute encephalitic syndrome (AES) consisting of (1) abrupt onset of fever, headache, and AS, (2) dystonias and various movement disorders, (3) opsoclonus and gaze palsies, (4) CSF findings, and (5) the presence of residual neuropsychiatric and neurological features in the survivors.

Functional modulation of dendritic cells and macrophages by Japanese encephalitis virus through MyD88 adaptor molecule-dependent and -independent pathways

Dendritic cells (DCs) are potent initiators of T cell-mediated immunity that undergo maturation during viral infections. However, few reports describing the interactions of DCs with Japanese encephalitis virus (JEV), which remains the most frequent cause of acute and epidemic viral encephalitis, are available. In this study, we investigated the interaction of JEV with DCs and macrophages. JEV replicated its viral RNA in both cells with different efficiency, and JEV infection of macrophages followed the classical activation pathway of up-regulation of tested costimulatory molecules and proinflammatory cytokine production (IL-6, TNF-alpha, and IL-12). On the contrary, JEV-infected DCs failed to up-regulate costimulatory molecules such as CD40 and MHC class II. Of more interest, along with production of proinflammatory cytokines, DCs infected by JEV released antiinflammatory cytokine IL-10, which was not detected in macrophages. Moreover, signaling through MyD88 molecule, a pan-adaptor molecule of TLRs, and p38 MAPK in JEV-infected DCs was found to play a role in the production of cytokines and subversion of primary CD4(+) and CD8(+) T cell responses. We also found that IL-10 released from JEV-infected DCs led to a reduction in the priming of CD8(+) T cells, but not CD4(+) T cells. Taken together, our data suggest that JEV induces functional impairment of DCs through MyD88-dependent and -independent pathways, which subsequently leads to poor CD4(+) and CD8(+) T cell responses, resulting in boosting viral survival and dissemination in the body.

Longitudinal studies of Japanese encephalitis virus infection in vector mosquitoes in Kurnool district, Andhra Pradesh, South India

A 4-yr (2002-2006) entomological study was carried out in Kurnool district, Andhra Pradesh state, south India, to identify the mosquito vectors of Japanese encephalitis virus (family Flaviviridae, genus Flavivirus, JEV). In total, 37,139 female mosquitoes belonging five genera and 18 species resting on vegetation were collected in villages and periurban areas at dusk. Mosquito species composition and pattern of JEV infection in mosquitoes varied in periurban and rural areas. In periurban area, Culex gelidus Theobald was abundant, making up 49.7% of total catch followed by Culex tritaeniorhynchus Giles (44.5%). In rural area, Cx. tritaeniorhynchus was predominant, making up 78.9% of total catch followed by Culex quinquefasciatus Say (10.8%), Anopheles subpictus Grassi (7.1%), and Cx. gelidus (1.1%). In light trap collections, Cx. gelidus and Cx. tritaeniorhynchus predominated in periurban and rural areas, respectively. Of 50,145 mosquitoes screened JEV isolations were made only from Cx. gelidus and Cx. tritaeniorhynchus. Based on high abundance and frequent JEV isolation, Cx. tritaeniorhynchus was found to be the principal vector in both areas, whereas Cx. gelidus plays a secondary vector role in periurban areas only.

Past, present, and future of Japanese encephalitis

Japanese encephalitis (JE), a vector-borne viral disease, is endemic to large parts of Asia and the Pacific. An estimated 3 billion people are at risk, and JE has recently spread to new territories. Vaccination programs, increased living standards, and mechanization of agriculture are key factors in the decline in the incidence of this disease in Japan and South Korea. However, transmission of JE is likely to increase in Bangladesh, Cambodia, Indonesia, Laos, Myanmar, North Korea, and Pakistan because of population growth, intensified rice farming, pig rearing, and the lack of vaccination programs and surveillance. On a global scale, however, the incidence of JE may decline as a result of large-scale vaccination programs implemented in China and India.

Usefulness of RT-PCR for the diagnosis of Japanese encephalitis in clinical samples

The present study was carried out between July 2003 and December 2005 in PGIMER, Chandigarh, India and aimed to compare IgM capture ELISA and nested RT-PCR for the diagnosis of Japanese encephalitis (JE). The samples collected were cerebrospinal fluid and blood from 40 febrile patients with encephalitis (n=40, group I) and blood samples from febrile patients without encephalitis residing in JE endemic areas (n=45, group II). Overall, in CSF samples JE specific RNA was detected in 9/40 (22.5%), while 7/28 (25%) patients showed the presence of specific IgM antibodies. Only 28 CSF samples could be subjected to both RT-PCR and IgM and, among these, 13 cases were found to be confirmed JE based on IgM and/or RT-PCR positivity. Among the confirmed cases, 6 (6/13, 46.5%) could be detected by RT-PCR alone, 4 (4/13, 30.7%) by IgM capture ELISA and 3 (3/13, 23.1%) patients were positive by both the methods. All the RT-PCR positive cases had presented within 5 d of onset of illness. The serum samples of only 16 patients in group I could be tested for IgM antibodies and 5 (31.25%) were found to be positive, while in group II, 11.1% (5/45) positivity was observed. JE specific RNA could not be detected in serum samples of either group of patients. This study highlights the need for carrying out RT-PCR in CSF samples, compared to IgM antibody detection, for the early detection of JEV.

Coinfection of Japanese encephalitis with neurocysticercosis: an imaging study

BACKGROUND AND PURPOSE

Coinfection of neurocysticercosis (NCC) and Japanese encephalitis (JE) has been advocated as more than a chance occurrence resulting in poor outcome. We undertook this study to determine whether the association of the 2 infections is more than a chance occurrence, to define the imaging characteristics of coinfections, and to explore the synergistic effect of NCC in JE.

MATERIALS AND METHODS

Sixty-two patients with JE were studied by MR imaging and CT. CT was done in 53 and MR imaging in 53 patients. The diagnosis of JE was established by CSF JE virus immunoglobulin M capture (MAC) enzyme-linked immunosorbent assay (ELISA). NCC was diagnosed from imaging. A control group of 385 patients was evaluated by imaging for prevalence of NCC in the general population.

RESULTS

A significantly high association of NCC with JE (19.3%) was observed in comparison with prevalence of NCC in control subjects (1.04%; P = .0003). JE lesions in coinfection were significantly asymmetric with lateralization to the side of the brain having the maximum NCC or a cyst with edema. The JE lesions in coinfections were more florid, with a significantly higher proportion of abnormal CT scans and more abnormal MR imaging. Coinfections were significantly more common in children. Significantly lower CSF MAC-ELISA units in patients with coinfection reflected low CSF IgM levels, suggesting altered immune status.

CONCLUSION

In our series, there was a strong association between JE and NCC, and, thus, this coinfection was more than a chance occurrence.

An insufficient anti-inflammatory cytokine response in mouse brain is associated with increased tissue pathology and viral load during Japanese encephalitis virus infection

Infection of the central nervous system with Japanese encephalitis virus (JEV) results in fatal encephalitis in humans. No reports exist describing the sequence of pathological changes and their correlation to the immune response in the brain following infection with JEV. In this report, we analyzed inducible nitric oxide synthase (iNOS) mRNA, proinflammatory (IFN-gamma, TNF-alpha) and anti-inflammatory (IL-4, IL-10) cytokine expression, viral load, and the correlation of these factors with the major histopathological changes in brain of JEV challenged mice at different time points during infection. We report for the first time that in JE, there is a progressive decline in the level of IL-4. The extent of progressive decrease in IL-4 and IL-10 level following viral infection is inversely correlated to the increased level of proinflammatory cytokines and histopathological changes with negative consequences following viral infection. In contrast, proinflammatory mediators like IFN-gamma and TNF-alpha were significantly upregulated (P < 0.05). A negative correlation between IFN-gamma and iNOS indicates their independent actions during JEV infection. To conclude, an insufficient anti-inflammatory cytokine response indicated by IL-4 and IL-10 in the brain is associated with increased tissue pathology and viral load, which regulates inflammatory responses driven by IFN-gamma in concert with TNF-alpha to cause brain tissue damage.

Immunological equivalence between mouse brain-derived and Vero cell-derived Japanese encephalitis vaccines

The persistent spread via animal reservoirs urges expanding vaccination programs against pathogens like the Japanese encephalitis virus, JEV. The JEV is spreads to new areas by domestic as well as by wild animals. Although there is a safe and efficient vaccine on the market, this is derived from infected mouse brains, why today's situation requires overcoming the potential risk caused by using animal tissues. To meet this demand we have developed a Vero cell-derived JEV vaccine, using the same virus strain as in the established one. A phase III clinical study of the new vaccine has recently been completed with positive outcome. Like the established mouse brain-derived vaccine, the Vero cell-derived one is a formalin inactivated whole virus vaccine. We here demonstrate the very good agreement in immunological tests between the two antigens. The study includes analyses with two neutralizing monoclonal antibodies that blocks cell entry at a late stage in infection, assumedly interfering with fusion-related refolding in the virus fusion protein. It is obvious that the formalin inactivation treatment, with both virus preparations, retains these essential vaccine epitopes.

A single tube RT-PCR assay for the detection of mosquito-borne flaviviruses

Mosquito-borne flaviviruses include several important agents of human disease and have provided striking examples of emerging infections. In this study we present the design and validation of a single tube RT-PCR assay using a pair of consensus primers for the detection of mosquito-borne flaviviruses. Sequencing of the amplicons permits the species identification. The assay was validated using RNA from the yellow fever virus vaccine strain and from representative strains of dengue viruses 1, 2, 3 and 4, West Nile virus, Kunjin virus (a clade of West Nile virus), and St. Louis encephalitis virus.