Determinants of Acute Encephalitis Syndrome (AES) in Muzaffarpur district of Bihar, India: A case-control study

BackgroundMuzaffarpur district in Bihar, India has witnessed several outbreaks of Acute Encephalitis Syndrome in the past decade with reportedly high case fatality in children under the age of 15 years. No study has documented the mode of transmission and nature of causative agent.MethodsA case-control study was conducted to assess the risk factors associated with AES. All cases reported from two hospitals in the district were selected with four controls per case selected randomly. Questionnaires were administered using geographical positioning system (GPS) enabled Tablets.ResultsThe median age was 4 years (IQR: 3-6.5) in both cases and controls. Case-fatality rate was 274 per 1000 AES cases. Logistic regression analysis showed significant association (p < 0.05) with literacy status, occupational status of parents, travel using public transport mode and presence of lychee orchard near the vicinity of households. Goodness-of-fit of model using chi-square statistic based on Hosmer-Lemeshow test was found to fit well for the final model (p = 0.353).ConclusionsOutbreaks of acute encephalitis of unknown origin coinciding with the harvesting season of lychee strengthens hypothesis of oral-faecal transmission.