Kerala Nipah crisis: Man who contained virus in 2001 sees no need to panic

To stop the spread, you may need to quarantine the area, says Dr NK Ganguly, former director, ICMR

When the first outbreak of Nipah (NiV) hit India in 2001 at Siliguri, N K Ganguly, the then director general, Indian Council of Medical Research (ICMR) and Director General of Health (DGH) was there to oversee, supervise and understand what was happening on the ground. Dr Ganguly is a Microbiologist specialising in tropical diseases. Currently, Dr Ganguly is the President of Apollo Hospitals Educational and Research Foundation (AHERF). He wrote the first paper in India on the Nipah virus. Excerpts from an exclusive interview:

When and where did the first outbreak in India take place?

In India, the first outbreak happened in 2001 at Siliguri district of West Bengal. The virus spread was very fast and people died. The dead were mostly nurses and caregivers -- people who were in close proximity to the affected. 

The intermittent outbreak of acute encephalitis-like symptoms occurred among residents living in closed areas in the town of Siliguri. The outbreak caused high fatality rates among infected persons. Cases and deaths reported among people living in close proximity to the infected patients included treating medical, nursing and paramedical personnel.

Initial investigations using index definitions of the symptoms did not classify the disease.  
 

How was the infection/ virus identified?

The first reported outbreak happened in Malaysia in 1998, so the sequence of virus was available even though the strain in Siliguri was different. 

Dr Ganguly

The biological samples were quickly collected from the cases and contacts and were sent to national and international laboratories for isolating and identifying the pathogenic organism. Thus the disease was identified as Nipah. Centre for Disease Control and Prevention (CDC-Atlanta, USA) confirmed through sequencing, that the strain was of Nipah virus. The first cases of infection from Nipah virus had been reported from Malaysia in the year 1998-99 which led to the discovery of a novel paramyxovirus. This was named as Nipah virus. In Siliguri it was also found that the source of the virus were bats. The infection was quickly controlled by educating the public to avoid contact with infected patients.

Ringing and noise interventions were used to disperse and chase away bats. Health workers were advised to handle patients by taking precautions, like usng N95 masks, wearing protective gear, avoiding fomite and standard precautions, including washing hands, using cap and gloves. Thus using the protective measures the infection was rapidly controlled.

Further analysis of the sequences of virus isolated from India showed variations in sequence homology when compared to the viruses isolated in Malaysia and from other outbreaks reported from Australia, where Nipah, from its reservoir host spilled over into the domestic pigs and ultimately infected the humans.

Another outbreak had also occurred in India, in Nadia district of West Bengal and then in neighbouring Bangladesh, where too the source of viral infection, were bats. Here too the infection spread among people living in close proximity and the transmission was quickly controlled in the confined area with implementation of effective measures.

We collected samples and cultured them and found a viral strain that cannot infect further in the case of Siliguri. So we started looking in-depth and found that it was the fruit bats which were responsible. If a fruit half-eaten by a fruit bat was eaten by a human, the saliva that the bat left behind caused the disease in human.

A similar Nipah viral  attack happened in Dhaka (2006), where again the culprit was a bat, although the sequence was different. It was contained quickly once the virus was identified. 

What can be done to contain the fallout?

The current outbreak in Kozhikode district of Kerala has also affected people living in close proximity and is spread by fruit bats. The infection is confined only to families infected by the disease and people in close contact with them, such as the treating health workers. The infection spread is also being controlled here by isolating the patients and using protective measures.

To contain the Nipah infection, the control of bat population is of paramount importance. A considerable research on bat behaviour has been done by late Dr M K Chandrashekharan from IISc, Bangalore. From his study findings, some of his selective techniques could be used to prevent bats from colonising and residing in human habitations. This should be rigorously implemented along with other public health measures like educating the masses in taking precautionary measures to stop further spread of Nipah virus infection.