Serological study of Japanese encephalitis in Nepal

Antibodies against Japanese encephalitis virus (JEV) were examined in 356 serum samples from individuals visiting Tribhuvan University Teaching Hospital using neutralization test. A total of 13.2% (47/356) seropositivity was observed. Antibody positivity against both Nakayama-NIH and Beijing-1 strains was seen in 7.9% subjects. Infection by Nakayama-NIH strain alone was seen to be 4.2% while 1.1% of study populations were found to be infected only by Beijing-1 strain. High antibody titer was observed in the 20-40 years age-group and did not increase with age. Seropositivity was more common in zone-A (Tarai) area compared to zone-B (Hills) and zone-C (Mountains). Spectrum of antigenicity of JEV in zone-A as shown by neutralization test was identical to Indian isolates (strains). Difference in seropositivity was observed against Nakayama-NIH and Beijing-1 strain in zone-B and C indicating recent spread of JEV in these areas.