Abstract :
Introduction: Japanese encephalitis (JE) is viral encephalitis that causes high morbidity and mortality and is endemic in large parts of West Bengal. Subclinical infections greatly outnumber overt cases of JE. The objective of this study was to detect cases of inapparent infections and the disease burden of JE in Bendubi garrison considered to be ‘endemic’ for JE.
Methods: JE disease burden was evaluated by detection of anti-JEV IgM in serum and cerebrospinal fluid (CSF) in 510 cases of acute encephalitis syndrome (AES) reporting to the base hospital in Bengdubi while inapparent infections were evaluated by detection of serum anti-JE IgG antibodies in a matched sample of 511 individuals.
Results: Fourteen (2.7%) of the 510 symptomatic cases that had presented to the hospital with fever or/and symptoms of acute encephalitis, tested positive for JEV infection. In the asymptomatic cohort, 429 out of 511 (83.9%) tested positive for the IgG antibody to JEV, giving an apparent: inapparent ratio of 1: 31.
Conclusion: The overall incidence of JE cases was lower than that reported from other ‘endemic’ regions of West Bengal. Residents of the area developed IgG antibodies and hence longterm immunity against JE, probably as a result of repeated subclinical infections. Anti-mosquito measures, JE vaccination and environmental modifications can break the transmission cycle and eventually eradicate JE completely.
Keyword :
Japanese encephalitis, Bengdubi, Acute encephalitis syndrome, Epidemiology, IgM, IgG, Zoonotic