JAPANESE ENCEPHALITIS AMONG HOSPITALIZED PEDIATRIC AND ADULT PATIENTSWITH ACUTE ENCEPHALITIS SYNDROME IN HANOI, VIETNAM 1995

The etiologic spectrum of acute encephalitis syndrome (AES) has not be en well defined in Vietnam. Cohort and case-control studies were perfo rmed on all adult and pediatric AES patients admitted to the Neurology Service of Each Mai Hospital between June 5 and August 3, 1995. Among pediatric AES patients, 31 (67%) of 46 had acute Japanese encephaliti s (JE), compared with only two (6%) of 33 adult AES patients (P < 0.00 01). For confirmed JE cases, serum specimens obtained 15-21 days after symptom onset had the highest mean anti-JE IgM signal-to-noise (PIN) ratios (8.08 + 1.09 SE). A serosurvey of adult household members did n ot reveal any cases of recent subclinical JE infection, although 26% h ad evidence of past JE infection. The use of bed netting was nearly un iversal but did not appear to reduce the risk of AES or JE. Given the high incidence of JE, particularly among children, Vietnam seems well suited for the development of a targeted JE vaccination strategy.