When an outbreak of encephalitis occured in Siliguri town of West Bengal in India in February 2001, investigators took nearly six months to conclude that it was a Nipah virus outbreak.
The outbreak that caused widespread panic among residents of Siliguri was brought under control only after 45 lives were lost. Recalling how the outbreak was handled then, N. Devadasan, Director of Institute of Public Health, who led the World Health Organisation’s outbreak investigation team then, said there is no need to panic as the infection is not air borne unlike H1N1 or SARS. “It can spread only if there is close contact with the infected person’s body fluids,” he said.
Adequate precautionary measures including total quarantine of infected persons and personal protection of those in close contact with the infected persons including the health staff will help, he said.
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Speaking to The Hindu on Wednesday, Dr Devadasan said the Siliguri outbreak was investigated by a team drawn from All India Institute of Medical Sciences (AIIMS), New Delhi; National Institute of Communicable Diseases (NICD), Delhi; National Institute of Virology (NIV), Indian Council of Medical Research, Pune and WHO Country Office. A retired health officer from Gujarat also participated in the investigations.
“The WHO’s assistance was sought as tests at NIV, Pune did not reveal definitive results. Though initial laboratory investigations indicated the outbreak to be due to non-exanthematous measles, subsequent epidemiological and laboratory investigations including those conducted at CDC, Atlanta, USA found the infection similar to the 1998-1999 outbreak of severe febrile encephalitis among pig farmers in Malaysia. This was caused by the emerging Nipah virus then,” Dr Devadasan recalled.
He said all the cases that were interviewed had a definite history of exposure to an infected case. There was no association with factors like travel outside Siliguri, visit by guests from outside Siliguri, attending funeral, exposure to injections, contact with animals/birds including pigs, exposure to any new or old insecticide or homeopathic remedies during one month prior to date of onset in the cases. “We concluded the infection could spread from person to person only if there was close contact with body fluids of the infected person, may be when the person had visited the patient in the hospital,” he explained.
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The investigating teams ensured all infected patients were quarantined. “It was made mandatory for all health personnel and those visiting patients in hospitals to wear single use (disposable) personal protection gears including masks, caps and slippers. Health facilities were upgraded and equipped with more ventilators as most of the 45 patients died due to breathlessness. After 20 days (two incubation periods), deaths reduced and no new cases were detected,” he explained reiterating that there is no need to panic.