Quantum Leap

Why Nipah virus has baffled scientists and experts

It still not clear whether the outbreak is a result of circulating virus within the country or is of imported origin.

 |  Quantum Leap  |  3-minute read |   29-05-2018
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The outbreak of the Nipah virus in Kerala is yet another reminder of how fast new viruses can travel from one country to another in a globalised world. Nipah is a relatively new virus which was discovered in 1999 in Sungai Nipah village in the Malaysian peninsula.

Within a short time, it made its way to Bangladesh which saw nine outbreaks in the year 2001 alone. The same year, Nipah struck in Siliguri, which is strategically located near international borders with Bangladesh, Nepal and Bhutan and sees movement of migratory labour from all sides. Its tropical climate is ideal for viruses to thrive.

The virus strains isolated from Siliguri was closely linked to that from Bangladesh and not to that isolated in Malaysia. After Siliguri, Nipah killed five people in Nadia, also in West Bengal, in 2007. Now, Nipah has surfaced in Kozhikode and Mallapuram. However, it still not quite clear whether the outbreak is a result of circulating virus within India or is of imported origin.

After the 2001 Siliguri outbreak, experts had warned of outbreaks elsewhere. The team of experts that investigated the outbreak reported that 45 deaths in Siliguri were either due to Nipah or closely related Hendra virus.

There was clear evidence of human-to-human transmission, but no evidence of any occurrence in animals. The team had underlined the need for a strong surveillance system backed by modern laboratories for handling and diagnosing new pathogens.

At a scientific conference in 2008, an expert from Dhaka-based International Centre for Diarrheal Disease Research in Bangladesh warned that Nipah was spreading in rural areas of Bangladesh and India and that it had high mortality rate — killing up to three-quarters of those infected.


Scientists from Bhopal's High-Security Animal Disease Laboratory reiterated a few years later that “preparedness, surveillance and constant vigil would have to be mounted continuously in the country,” in view of the fact that antibodies of Nipah had been found in bat populations in the Northeast as well as north-west states like Haryana. The presence of antibodies indicates that the virus may be circulating among bats.

However, scientists are still not clear about exact transmission route of Nipah because every outbreak has presented a different picture. In Bangladesh outbreaks, fruit bats contaminated palm sap which people consumed and got infected.

The involvement of pigs and even dogs in the transmission chain of Nipah can’t be ruled out. Despite warnings from time to time, Nipah has resurfaced.

This means India’s disease surveillance system is still not robust enough. While the Integrated Disease Surveillance System exists, serious gaps have been found in implementation on the ground.

Studies done to assess its effectiveness have shown that it’s not as intense as it’s supposed to be and by the time new infections are likely to be detected, the disease would have already spread. Training and retraining of health workers, who are supposed to be the eyes and ears of the surveillance system, too are lacking.

Laboratory network for quick diagnosis also needs to be expanded and strengthened. Hopefully, Nipah will spur the much-needed action and investment to strengthen basic healthcare system.

(Courtesy of Mail Today)

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Dinesh C Sharma Dinesh C Sharma @dineshcsharma

Journalist, columnist and author based in New Delhi.

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