Nipah/Hendra virus outbreak in Siliguri, West Bengal, India in 2001

The viral encephalitides caused by animal or human viruses are characterized by sudden outbreaks of neurological disease in both tropical and temperate regions. An outbreak of acute encephalitis occurred in Siliguri (West Bengal) town of India between January 31 and February 23, 2001. This outbreak was investigated by a team of scientists from four major institutions, and the findings are presented here.

Detailed information about the outbreak was collected with the help of local health authorities. Limited entomological investigations were also done. Samples collected from cases and contacts were sent for analysis.

A total of 66 probable cases and 45 deaths were reported. Epidemiological linkages between cases point towards person-to-person transmission and incubation period of around 10 days. There was neither any concurrent illness in animals nor was there any exposure of cases to animals. Centres for Disease Control and Prevention, Atlanta, USA concluded on the basis of tests carried out on serum specimen from four cases and two contacts that the causative pathogen appears to be Nipah/ Hendra or closely related virus.

This outbreak highlights the importance and urgency of establishing a strong surveillance system supported by a network of state-of-the-art laboratories equipped to handle and diagnose new pathogens and including patient isolation techniques, use of personal protective equipment, barrier nursing and safe disposal of potentially infected material in the prevention and control measures for Nipah/Hendra virus infection.