West Nile Viral Detection in Thai Patients with Viral Encephalitis during 2007-2013

Abstract

West Nile virus (WNV) is belonged to the Flaviviridae family. It was transmitted to humans through Culex mosquitoes. Humans infected with WNV are usually asymptomatic. Less than 1.0% of symptomatic patients develop severe neurological diseases including meningitis and encephalitis. The case fatality rate is 4.0-14.0%. According to the International Health Regulations 2005 (IHR), WNV infection is a disease that member states must report its outbreaks to the World Health Organization. The purpose of this study was to determine the WNV infection case in Thailand. We performed WNV detection in samples collected from viral encephalitis patients sending to National Institute of Health during 2007- 2013. The samples were collected within 5 days after onset. The viral RNA was extracted from 368 CSF samples and 478 serum samples. The RT-PCR and Real-time RT-PCR in CSF were performed to detect WNV RNA from 245 and 601 samples, respectively. All 846 samples were negative. The detection of antibody either IgM or IgG against WNV by ELISA and indirect immuno-fluorescence test were shown the cross reaction with JEV and dengue antibodies. In conclusion, there was no evidence of WNV infection in Thailand during 2007 to 2013.