Hospital-based surveillance for Japanese encephalitis at four sites in Bangladesh, 2003-2005

Abstract

We investigated the epidemiology and etiology of encephalitis at four tertiary hospitals in Bangladesh during 2003-2005. Patients who met a clinical case definition for acute encephalitis and had cerebrospinal fluid (CSF) pleocytosis were eligible for enrollment; a standardized sampling pattern was used to enroll eligible patients. Recent Japanese encephalitis virus (JEV) infection was defined by presence of IgM antibodies against JEV in CSF or serum. Twenty (4%) of 492 cases had laboratory evidence of recent JEV infection; two died. All JE cases occurred during May-December, and cases were identified among all age groups. All cases resided in rural areas. Fifteen patients were re-assessed 4-6 weeks after hospitalization; 5 (33%) patients had physical disabilities and 7 (47%) reported cognitive difficulties. Infection with JEV is clearly an etiology of encephalitis in Bangladesh. Population-based studies to quantify burden of disease could assess options for targeted immunization programs.

Figure 1.

Districts of Bangladesh showing percentage of all line-listed acute encephalitis cases and distribution of Japanese encephalitis cases. This figure appears in color at www.ajtmh.org.

Figure 2.

Flowchart for acute encephalitis cases, Bangladesh, June 2003–July 2005.

Figure 3.

Number of Japanese encephalitis cases, by month of symptom onset, Bangladesh, June 2003–July 2005.