Outbreaks and Sporadic Cases of Japanese Encephalitis in the State of Odisha, India: Outcome of 7 Years of Laboratory Surveillance

Acute encephalitis syndrome (AES) is a major public health challenge in India. We report here the epidemiology of sporadics and outbreaks of Japanese Encephalitis (JE) in Odisha state during 2012–2018. A total of 4235 AES cases (sporadics – 3394, outbreak cases – 841) recorded including 42 outbreaks; majority (n = 18) of which were during 2016. Overall JE virus (JEV) positivity was 11.78% (outbreak cases – 24.5%, sporadic cases – 8.6%). Age ≤15 years were largely affected during outbreaks, while 16–60 years population was dominant among sporadics. The major outbreak (2016) involved 336 patients from a tribal dominated district, spread over 173 villages. JEV seropositivity was high (43.45%) with 28.57% mortality. Epidemiological linkage with pig rearing was documented through JEV neutralizing antibodies in 50% of pig serum samples. Although the postvaccination period (2017–18) showed increase in AES case reporting but low JE proportion. Ongoing surveillance and preparedness of the health system would be of importance, especially in tribal‑dominated districts.

ACUTE ENCEPHALITIS SYNDROME IN A TERTIARY CARE SETTING WITH SPECIAL REFERENCE TO JAPANESE ENCEPHALITIS: AN OBSERVATIONAL STUDY IN ASSAM, INDIA

Acute Encephalitis Syndrome (AES) is a major public health problem and Japanese Encephalitis (JE) is one of the most important causes of AES. Therefore, it is crucial to know the etiology of AES for patient management and decision making. The present study aimed to assess the morbidity and mortality profile of AES/JE patients admitted in tertiary care setting. An observational prospective cross-sectional study was conducted among 140 hospitalized AES patients admitted in Pediatric and Medicine ward of Jorhat Medical College and Hospital (JMCH), Jorhat over a period from August, 2017 to July 2018. Blood serum and cerebrospinal fiuids (CSF) were tested for presence of JE specific IgM antibody by Mac ELISA during acute illness of AES. The data were compiled and analyzed using the IBM SPSS, V23.0. Of the total 140 AES cases, majority (60%) were below 15 years age (p-value 0.180). Significantly higher proportion of AES cases were from rural areas (94.3%) (p-value <0.0001). The male and female ratio was 1.3:1. The most common presenting symptoms in AES patients were fever (100%), change in mental status (100%), seizure (56.4%) and headache (42.9%). Signs of meningeal irritation were present in 69.3% of cases. Around 22.9% AES patients had GCS ? 8. A total 49 (35%) cases were found to be laboratory confirmed JE following detection of JE specific IgM antibody. Among the JE patients, only 4.1% were immunized with SA 14-14-2 vaccine and 14% died before discharge. The complete recoveries were observed in 78% of cases. JE is one of the major causes of AES which is highly prevalent in this part of India. The significant findings in the present study calls for policy decision to combat JE.

Evidence of natural infection of Orientia tsutsugamushi in vectors and animal hosts � Risk of scrub typhus transmission to humans in Puducherry, South India

Background: Scrub typhus infection is endemic in India and reported to be the major cause for acute encephalitis syndrome (AES) in humans. Periodic occurrence of scrub typhus cases and presence of pathogen in rodents were also reported in areas with human cases of scrub typhus in Puducherry. Objectives: This study was carried out to screen Orientia tsutsugamushi in rodent/shrew reservoirs and vectors in villages of Puducherry with no reports of human scrub typhus cases. Methods: This study was conducted during October 2017 to January 2018 in ten randomly selected villages in Puducherry. Rodents/shrews in the peridomestic area were trapped using Sherman traps. Screening of O. tsutsugamushi in rodents/shrews and mite vectors was done by polymerase chain reaction (PCR). Weil-Felix test was done to screen antibodies against O. tsutsugamushi in rodent serum samples. Results: Among the 54 rodents trapped, Suncus murinus was the major small animal and Leptotrombidium deliense was the major mite species retrieved. PCR screening revealed pathogen positivity in 8 rodent blood and 3 pooled mite samples. Phylogenetic analysis has shown that Kato was the circulating serotype of O. tsutsugamushi. None of the rodent serum samples was tested positive for antibodies against O. tsutsugamushi by Weil-Felix test. Conclusions: The presence of pathogen in both vectors and reservoir animal hosts imposes a risk for scrub typhus transmission to the inhabitants; hence, initiation of vector control measures before the start of winter is recommended in the study area. It is also recommended to screen scrub typhus in patients with undifferentiated acute febrile illness and AES.

Clinical Profile and Predictor of Adverse Outcome in Children with Acute Encephalitis Syndrome: A Cross Sectional Study.

Background: Acute Encephalitis Syndrome (AES) isdefined as a person of any age at any time of year, withthe acute onset of fever and a change in mental statussuch as confusion, disorientation, coma or inability totalk and/or new onset of seizures (excluding simplefebrile seizure). Most cases of AES are due to viralencephalitis, which is more prevalent in South EastAsia. Aim and Objectives: to study clinical profile andrisk factors for adverse outcome of AES in children inAcharya Vinoba Bhave Rural Hospital (AVBRH).Material and Methods: This cross-sectional,observational study was conducted in children withAES admitted in Pediatric Intensive Care Unit (PICU)of AVBRH over period of 2 years (August 2017- July2019). Data collection were done by using predesigned,structured proforma and analyzed by using SPSSversion 22. Results: Of the 80 cases enrolled in the study31.25% were between 10-15 years. In this study male tofemale ratio was 1.5. Mostly subjects were residing inrural area (54.1%), with a common presentation of fever(100%), altered sensorium (73.7%) and convulsion(71.25%). Mortality was observed in 23.7% cases out ofwhich 40(50%) had viral etiology (other than dengue),21(26.25%) had dengue, 5(6.2%) had malaria. Thosewho presented with shock and required mechanicalventilation and had deranged Liver Function Test (LFT)profile have statistically significant correlation withmortality. Conclusion: Majority of cases were in the agegroup 10-15 years, with male predominance. DerangedLFT, presence of shock significantly associated withmortality among children with AES. Viral encephalitisis an important cause of AES

Study on acute encephalitis syndrome in children and their correlation with clinical parameters and etiological factors

'Background: Acute encephalitis is the clinical diagnosis of children with acute onset of symptoms and signs of inflammatory lesions in the brain. It must be diagnosed promptly for saving life and preserving brain functions.Authors objectives was to determine the profile and outcome of children admitted with Acute Encephalitis Syndrome (AES) and to identify etiological factors.Methods: Study consist of a retrospective analysis of hospital records of children up to 15 years of age admitted with a diagnosis of AES in the pediatric ward, Narayana medical college, Nellore from January 2018 to June 2019.Results: In a total of 30 patients of AES, clinical features like fever (100%), altered sensorium (100%), convulsion (40%), headache (45%) and neuro deficit (40%) and vomiting (50%). The average Glasgow coma scale at admission was 8. There are 55% of cases in the 5 to15 yr age group (p>0.05). Both Encephalitis (56.6%) and meningitis (43.3%) were documented significantly more in males as compared to females (p<0.01). Twenty-one cases are discharged, eight expired, and 1 case was referred (p<0.001). JE IgM positive cases contributed to 36.6%, of which eight males and three females recorded between 5-15 years. Male children are more likely to play outdoors where the mosquito vector of the disease is abundant.Conclusions: JE has significant morbidity and mortality, can be prevented by immunization, and reduced if supportive interventions are provided in time. Preventive measures must be taken for 5-15 years of age group those playing outdoors, going to school or agriculture fields predisposing them to vector mosquito bite.

Seroprevalence of Japanese encephalitis amongst cases of acute encephalitis syndrome in a tertiary care centre of north east India: a four year retrospective study

Background: The present study was undertaken to investigate the trend of JE and the different parameters associated with it.Methods: It was a hospital-based retrospective study conducted from January 2014 to December 2017. A total of 3531 consecutive non-repetitive patients, satisfying the clinical case definition of AES as per the WHO guidelines, were included in the study. Cerebrospinal fluid (CSF) and serum samples were tested for JEV-specific IgM antibodies by the NIV JE IgM Capture ELISA Kit.Results: Of the 3531 patients admitted, 838(23.7%) cases were positive for JE IgM antibodies. There was a significant reduction in the JE positivity rate from 32.9% in 2014 to 13.3% in 2017. The male-to-female ratio was 1.6:1. JE positivity rate was significantly higher in adults as compared to children. The majority of cases occurred during the monsoon and post-monsoon season. Fever (100%), change in mental status (87.8%), headache (70.5%), neck rigidity (32.4%), unconsciousness (35.4%), seizure (43.9%) and paralysis (5%) were the major clinical symptoms. JE positivity was seen to be higher in the rural areas of Assam.Conclusions: A declining trend of JE was seen in this study, however further research work needs to be done to look for non-JE causes of AES.

A six years prospective epidemiological study of acute encephalitis syndrome among children admitted in a rural tertiary care center

Background: Acute Encephalitis Syndrome (AES) is a major public health issue in India. The common etiologies of AES in India are various infectious agents. There are seasonal and regional variations in etiologies making diagnosis and effective intervention often difficult. Our study represents the epidemiological data that will help in planning management in larger perspective.Methods: This is a six years prospective observational study conducted in the Department of Pediatrics, North Bengal Medical College Hospital, Darjeeling from January 1st, 2013 to December 31st, 2018. In this study all clinically diagnosed AES cases were included fulfilling inclusion and exclusion criterion.Results: 585 out of 39420 patients (1.48%) were diagnosed clinically as AES over six years. Male patients (372) contributing to 63.6% and female patients (213) 36.4% of the study. Majority cases (271) were seen in the age group of 1-5 years amounting to 46.3% with mean age 5.1'3.6 years. In July 2014 number of cases were maximum 59 (10%) followed by May 2013 20 (3.4%). Among the 585 AES cases, 263 (45%) were suspected for viral etiology (JE= 84, 14.3%). Total 457 cases (78.1%) were alive with insignificant to age and gender variance. Vaccination status revealed 11 among 15 JE deaths were unimmunized which is statistically significant (p < 0.05) by Chi-square test.Conclusions: The magnitude and etiologies of AES need to be explored and understood in various geographic regions and in different seasons to have a better insight for development of future policies to reduce the burden.

A Study of the Clinico-Etiological Profile of Acute Encephalitis Syndrome Cases in a Tertiary Care Hospital of Upper Assam with Special Reference to Japanese Encephalitis

Introduction: Acute Encephalitis Syndrome is a major health problem in Assam, claiming thousands of lives every year and crippling the survivors. Japanese Encephalitis is the leading agent of this group. Much emphasis has been given to the vaccination drive but the effort has not been fruitful. This study aims to explore the common presentations of these diseases, the causative agents and the vaccination status of those affected. Material and methods: This is a single centre observational study carried out in Unit-V of the Department of Medicine of Assam Medical College and Hospital, Dibrugarh for a period of two years. Acute Encephalitis Syndrome was defined as per World Health Organisation definition. Data were collected and serum and CSF were analysed in search of the etiologic agent. Results: Of the 74 cases studied, 37 tested positive for Japanese Encephalitis. Fever, altered sensorium and seizure were the most common presentations. Herpes Simplex had 50% mortality, the highest among all the agents tested for. Only 2 out of 37 cases had been vaccinated against Japanese Encephalitis. Conclusion: Acute Encephalitis Syndrome is a major threat to public health, particularly in Assam. Adequate vaccination coverage could prevent significant morbidity and mortality.

Profile of Pediatric Scrub Typhus in Odisha, India

Objective: To investigate the distribution and clinical profile of scrub typhus infection amongchildren with acute febrile illness in Odisha. Methods: Children (<15 y) presenting with acutefever (>5 days) in 4 agro-climatic zones from June to November 2017 were evaluated.Patients were screened for malaria, leptospira, dengue, typhoid and scrub typhus. Scrubtyphus was confirmed by IgM ELISA and PCR. Results: Out of413 casesexamined, 48.7%were positive for scrub typhus, and 5.5% of them developed systemic complications. Escharwas found in 17.9% of cases. Five days treatment of Doxycycline and/or Azithromycin wasclinically effective against scrub typhus. Conclusion: Our study highlights that scrub typhusis one of the causes of high morbidity in children during rainy months in Odisha.

Analysis of outcome of acute encephalitis syndrome after inclusion of coverage against scrub typhus

Background: Acute encephalitis syndrome (AES) has emerged as a major epidemic in Bihar and is associated with high mortality. Owing to the increasing burden of disease and its associated morbidity and mortality, studies were undertaken to evaluate specific etiology of AES. Some studies suggested emergence of scrub typhus as a major cause of AES accounting for about 25% of the cases1. A Standard Operating Procedure (SOP) was developed for treatment of AES cases in Bihar which included addition of Injection Azithromycin (@ 10 mg/kg for 7 to 10 days in case of suspected mycoplasma/rickettsial infection. The objective of the study is to compare the outcome of AES before and after the inclusion of coverage against rickettsial infection.Methods: It is a randomized controlled trial conducted in the Department of Pediatrics, Patna Medical College and Hospital, Patna from January 2016 to August 2018.Results: Total number of patients enrolled in both the groups were 127 and 88 respectively. No significant difference were seen in the baseline socio- demographic characteristics of the two groups. Case Fatality Rate in the 1st group (without inclusion of Azithromycin) was 39.3% while in the 2nd Group (with Azithromycin) was 12.5%.Conclusions: Due to the emergence of scrub typhus as a major etiological factor for AES, inclusion of coverage against it along with measures like widespread immunization against Japanese Encephalitis and prompt management of complications and euglycemia, can result in steady decline in the death rates due to AES.

Encephalitic presentation of Neonatal Chikungunya: A Case Series

Objective: To describe clinical features and early neurological outcomes in neonatalChikungunya. Methods: Clinical, pathological and radiological details of neonates with acuteencephalitic features and typical rash, later diagnosed as Chikungunya, are presented.Neurodevelopmental evaluation and imaging was done at discharge/three months. Results:Abnormal neurological examination with fever was typical presentation in all 13 babies with/without seizures/peri-oral rashes; 12 had persistent neurological abnormalities at discharge.A follow-up at three months revealed continued neurodevelopmental deficits. Neuroimagingabnormalities were seen in eight out of ten cases. Conclusions: Perinatal Chikungunyashould be considered in neonates presenting within first week with fever, encephalopathy andperioral rashes with/without seizures with history of maternal Chikungunya within last weekbefore delivery.

Serum neuron specific enolase is increased in pediatric acute encephalitis syndrome / 소아과

PURPOSE: This study aimed to investigate whether serum neuron-specific enolase (NSE) was expressed in acute encephalitis syndrome (AES) that causes neuronal damage in children. METHODS: This prospective observational study was conducted in the pediatric neurology ward of Soetomo Hospital. Cases of AES with ages ranging from 1 month to 12 years were included. Cases that were categorized as simple and complex febrile seizures constituted the non-AES group. Blood was collected for the measurement of NSE within 24 hours of hemodynamic stabilization. The median NSE values of both groups were compared by using the Mann-Whitney U test. All statistical analyses were performed with SPSS version 12 for Windows. RESULTS: In the study period, 30 patients were enrolled. Glasgow Coma Scale mostly decreased in the AES group by about 40% in the level ≤8. All patients in the AES group suffered from status epilepticus and 46.67% of them had body temperature >40℃. Most of the cases in the AES group had longer duration of stay in the hospital. The median serum NSE level in the AES group was 157.86 ng/mL, and this value was significantly higher than that of the non-AES group (10.96 ng/mL; P<0.05). CONCLUSION: AES cases showed higher levels of serum NSE. These results indicate that serum NSE is a good indicator of neuronal brain injury.

Acute Encephalitis Syndrome (AES) as a Cause of Unfortunate Maternal Fetal Demise during the Japanese Encephalitis Epidemic - A Case Report.

Acute encephalitis syndrome (AES) is defined as the acute-onset of fever with change in mental status and often with new onset of seizures. Japanese encephalitis has been considered as the leading cause of AES in India. JE with pregnancy causes diagnostic dilemma especially in 3rd trimester if the patient presents with convulsion and altered sensorium; as in our case. It is often confused with eclampsia. But careful history and clinical investigation is helpful towards correct diagnosis

An outbreak of Japanese encephalitis after two decades in Odisha, India.

Sudden deaths in children due to acute encephalitis syndrome (AES) from a tribal dominated district of Malkangiri in Odisha, India, was reported during September-November, 2012. The investigation was carried out to search for the possible viral aetiology that caused this outbreak. Clinico-epidemiological survey and seromolecular investigation were carried out to confirm the viral aetiology. Two hundred seventy two suspected cases with 24 deaths were observed. The patients presented with low to moderate grade fever (87%), headache (43%), vomiting (27%), cold (18%), cough (17%), body ache (15%), joint pain (15%), rash (15%), abdomen pain (9%), lethargy (5%), altered sensorium (8%), convulsion (2%), diarrhoea (3%), and haematemesis (3%). Laboratory investigation showed Japanese encephalitis virus (JEV) IgM in 13.8 per cent (13/94) in blood samples and JEV RNA in one of two cerebrospinal fluid (CSF) samples. Paddy fields close to the houses, high pig to cattle ratio, high density (33 per man hour density) of Culex vishnui mosquitoes, low socio-economic status and low health awareness in the tribal population were observed. This report confirmed the outbreak of JEV infection in Odisha after two decades.

An appraisal of clinicopathological parameters in Japanese encephalitis and changing epidemiological trends in upper Assam, India.

Context: Japanese encephalitis (JE), an acute mosquito-borne viral disease, is one of the leading causes of viral encephalitis in the South-East Asian region. JE is endemic in Assam. The morbidity and mortality due to JE is significant with outbreaks every year during the monsoons. Aims: The aim was to study the clinicopathological profile of JE; to examine their role in predicting disease outcome; and to document the increase in the incidence of JE among the adult population in this region. Materials and Methods: Clinically suspected acute encephalitis syndrome (AES) cases admitted in Assam Medical College and Hospital during the period of May 2011 to April 2012 were tested by JE virus specific Immunoglobulin M capture ELISA. Statistical Analysis Used: Data analysis was performed using SPSS version 16.0. Results: Out of 424 AES cases, 194 were JE positive. The occurrence of JE in adults was higher (P < 0.001) than the pediatric age group. The study recorded a high rate of renal dysfunction in JE cases. A single case of JE induced abortion and two cases of JE-neurocysticercosis coinfections were documented. Regression analysis revealed that adult population, unconsciousness, paresis and elevated cerebrospinal fluid protein level were associated with a worse prognosis in JE cases. Mortality in JE positive cases was higher than the JE negative cases (P = 0.001). Conclusion: The study attempts to highlight the role played by a combination of clinical and laboratory parameters in assessing the severity and outcome in JE and may help in directing the limited medical resources toward those that need it the most.

Whose Failure? Encephalitis Kills.

Encephalitis continues to be one of the most dreaded diagnoses because a high rate of morbidity and mortality are accepted even before starting the treatment. Most encephalitis cases occur in rural areas due to poor environmental sanitation, highvector density, shortage of protected water supplies and lack of health education. Vaccination, environmental sanitation, vector control, health education and attention to prompt diagnosis and treatment in rural hospitals are the four essential pillars for reducing case fatality rate (CFR) of encephalitis. Frequently, virulence of the virus, immunological state of the host, unavailability of antiviral drugs and lack of enough tertiary care hospitals (TCH) are not responsible for the high CFR. Basic supportive care is not being practiced meticulously in Primary and Secondary Care Hospitals (PSCH), and their services are not being utilized fully. Main causes of high mortality and morbidity rates are hypoxia and ischemia of brain and other organs precipitated by preventable, controllable or treatable complications due to lack of basic medical and nursing care during transport to the TCH. Undiagnosed Rickettsial infections are suspected to be partly responsible for the high CFR in some areas. Improving rural hospitals and their ambulance services are the most economical way to reduce CFR. “Treatment facilities must be made available at places where cases occur.” The best way to reduce CFR of encephalitis in developing and underdeveloped countries is to increase and improve PSCH and sensitize politicians, administrators, medical/nursing professionals and more importantly to impress and convince the public to utilize them.

Isolation of Chandipura virus (Vesiculovirus: Rhabdoviridae) from Sergentomyia species of sandflies from Nagpur, Maharashtra, India.

Background & objectives: An outbreak of acute encephalitis syndrome was reported from Vidarbha region of Maharashtra state, India, during July 2012. Anti-IgM antibodies against Chandipura virus (CHPV) were detected in clinical samples. Sandfly collections were done to determine their role in CHPV transmission. Methods: Twenty nine pools of Sergentomyia spp. comprising 625 specimens were processed for virus isolation in Vero E6 cell line. Diagnostic RT-PCR targeting N-gene was carried out with the sample that showed cytopathic effects (CPE). The PCR product was sequenced, analysed and the sequences were deposited in Genbank database. Results: CPE in Vero E6 cell line infected with three pools was detected at 48 h post infection. However, virus could be isolated only from one pool. RT-PCR studies demonstrated 527 nucleotide product that confirmed the agent as CHPV. Sequence analysis of the new isolate showed difference in 10-12 nucleotides in comparison to earlier isolates. Interpretation & conclusions: This is perhaps the first isolation of CHPV from Sergentomyia spp. in India and virus isolation during transmission season suggests their probable role in CHPV transmission. Further studies need to be done to confirm the precise role of Sargentomyia spp. in CHPV transmission.

Clinical Profile and Outcome of Acute Encephalitis Syndrome in Dhulikhel Hospital of Nepal.

Introduction: Acute encephalitis syndrome (AES) is a constellation of clinical signs and or symptoms i.e. acute fever with acute change in mental status. AES may be present as encephalitis, meningoencephalitis or meningitis. It can be associated with severe complication, including impaired consciousness, seizure, limb paresis or death. Materials and Methods: Study consisted of retrospective analysis of hospital records of children up to 16 years of age admitted with diagnosis of AES in the department of Paediatrics Dhulikhel Hospital, Kathmandu University Teaching Hospital, Dhulikhel Kavre from January 2010 to December 2011. Results: During the two years (January 2010 to December 2011), 47 patients of AES were admitted. Among the admitted cases there were 34 male and 13 female patients. Meningitis cases were 29, encephalitis cases were 14 and 4 meningoencephalitis cases. Among the meningitis cases, viral meningitis accounted for 12, bacterial meningitis accounted for 15 and 1 tubercular meningitis.One was eosinopilic meningitis in which the causative organism was found to be fasciolosis by ELISA. Viral encephalitis was found to be the most common cause of encephalitis. Sensorineural hearing loss was seen in 3 cases, subdural effusion in 1 and hydrocephalus in 1. One patient had intracranial hemorrhage with hemiparesis as a complication of eosinophilic meningitis. Conclusion: Acute encephalitis syndrome is one of the most common causes of PICU admission in Dhulikhel hospital. Bacterial meningitis was common among the acute encephalitis syndrome followed by viral meningitis. One case of eosinophilic meningitis with intracranical hemorrhage and hemiparesis was found. Sensorineural hearing loss was found to be commonest complication.

On-site assessment on the definition and classification of suspected cases in the manual of WHO Japanese Encephalitis Surveillance Standards / 中华流行病学杂志

Objective To assess the new edition of WHO Japanese Encephalitis (JE) Surveillance Standards (WHO Standards) based on syndrome surveillance data and to provide field evidence regarding the standards. Methods Based on syndrome surveillance data, acute encephalitis syndrome (AES) case was categorized, according to the WHO Standards. A cohort study was applied to estimate the AES definition set in the Standard and relative risk was computed to estimate the existence and intensity of statistical correlation between AES and JE cases. Percentage of attributable risk was counted to describe the coverage of AES for JE cases in the studied population. Sensitivity,specificity, Youden index and positive predictive value of AES components were calculated for the purpose of identifying the clinical values under the screening program. Results 1424 suspected cases were evaluated in the surveillance program and 1396 cases with ELISA result, of which 109 positive cases were detected. According to the "standardized" classification, a total of 706 cases in line with AES case deftuition, were categorized into 83 cases of JE, 425 cases of AES unknown and 198 cases of AES other agent. In the cohort study,a relative risk of 4.62 (95% CI:2.80-7.63 ) and the percentage of attributable risk as 78.35% (95% CI: 64.25% -86.89% ) were observed. Conclusion The AES definition for JE was significantly effecting on the screening programs and a strong correlation strength was observed in the study. AES syndrome could cover most of the JE cases. "Convulsions",with appreciative screening value, was recommended to be involved into the new version of the WHO Standards.

Chandipura virus encephalitis outbreak among children in Nagpur division, Maharashtra, 2007.

Background & objectives: An outbreak of acute encephalitis syndrome (AES) among children from Nagpur division, Maharashtra was investigated to confirm the aetiology and to describe clinico-epidemiological features. Methods: AES cases among children <15 yr, from Nagpur division, hospitalized between June-September 2007, were investigated. Serum and cerebrospinal fluid (CSF) were tested for IgM antibodies against Chandipura virus (CHPV) and Japanese encephalitis virus (JEV) and for CHPV RNA by RT-PCR. Partial N gene sequences were used for phylogenetic analysis. Virus isolations were attempted in rhabdomyosarcoma (RD) cell line. Sandflies were collected, pooled and tested for CHPV RNA by RT-PCR. Results: A total of 78 AES cases were recorded in children <15 yr of age. Case fatality ratio was 43.6 per cent. Male to female ratio was 1:1.2. Chandipura (CHP) was confirmed in 39 cases. CHPV RNA was detected in both CSF and serum specimens of 2 cases and in serum of 22 cases. Phylogenetic analysis showed 99.98 – 100 per cent nucleotide identity in the sequences studied. Anti-CHPV IgM antibodies were detected in CSF of 2 cases and in serum of 8 cases. Seroconversion to anti-CHPV IgM antibodies was observed in 5 cases. Clinical manifestations of CHP cases (n=38) were fever (100%), convulsion (76.3%), altered sensorium (34.2%), headache (23.7%), vomiting (44.7%) and diarrhoea (23.7%). CHPV RNA was detected in one of two pools of sandflies from affected locality. Interpretation & conclusions: Chandipura virus was confirmed as the aetiological agent of this acute encephalitis outbreak with high case-fatality among children.