Nipah surveillance in Bangladesh for outbreak detection and prevention

Nipah virus (NiV) is an emerging zoonotic disease. Since 2001-2010, nine outbreaks of NiV infection were identified in Bangladesh. Onset of illness of all cases except one were December to March. Hospital based surveillance was established to identify cluster of cases of acute meningo-encephalitis and quick detection of Nipah outbreak. It is ongoing in hospitals of four medical colleges and two districts, in Nipah affected areas. A cluster is defined as onset of illness of two cases with fever and altered mental status who live within two kilometer area or within 30 minutes walking distance. The surveillance team collects serum and CSF samples from all cases of meningo-encephalitis. Rapid collection are done for rapid identification, characterization and genetic variation of Nipah viraus. The surveillance system has identified 46 cluster of cases of which four were due to Nipah outbreak and 24 cases were detected. Three of the four outbreaks had clear evidence for patient's intake of date palm sap and two had evidence of person to person transmission. In addition, the surveillance identified 6 isolated cases. Surveillance quickly detected outbreak at Thakurgaon in 2007, outbreak in Rajbari and Manikgonj in 2008 and Bhanga, Faridpur in 2010. Surveillance have public health impact for rapid identification of cluster, dissemination of prevention messages, reduce risk of person to person transmission, control outbreak, improve case management and reduction of mortality.