Bat populations in many Indian States harbour serological evidence of exposure to Nipah virus,” the Nature article points out. 
| Photo Credit: CraigRJD

Many places in Southeast Asia, such as Myanmar, Thailand, Laos, southern China, Bhutan, Nepal, Sri Lanka and some Indian States, have Nipah virus reservoirs and could experience cross-species transmission to humans, says an article published in the recent issue of Nature journal.

The article in the ‘World view’ section, titled ‘a personal take on science and society’, is authored by T.S. Anish, one of the leaders of the Nipah surveillance team in Kerala, and epidemiology professor at Government Medical College, Manjeri, Malappuram.

Based on his experience during the 2018 and 2023 outbreaks in the State, Dr. Anish calls for more scientific and policy work on the infection.

As a key first step, all countries likely to have Nipah virus reservoirs should have early detection systems. “The strain in Kerala’s outbreaks originated from Bangladesh in 2001. Health systems have missed this strain because its mortality rate is so high that it often causes small outbreaks or single cases,” he says.

“To reach Kerala, the virus must have spread undetected over more than 2,000 km, from Bangladesh or the neighbouring Indian State of West Bengal. It is highly probable that many places in Southeast Asia have Nipah virus reservoirs and could experience spillovers. Myanmar, Thailand, Laos, southern China, Bhutan, Nepal, Sri Lanka and many Indian States all lie in a similar distance from Bangladesh and are home to fruit bats. Bat populations in many Indian States harbour serological evidence of exposure to Nipah virus,” the article points out.

Dr. Anish says that lack of treatment options for Nipah is a concern as drug trials are difficult because outbreaks typically last for only a few days. “Kerala’s experience is that using antivirals not specific to Nipah might have helped some people infected near the end of the outbreaks in 2018 and 2023. More research is needed, as is wider distribution of general antivirals,” he says.

The development of monoclonal antibodies from Nipah survivors in Kerala is also a priority. These will be specific to the local variant and could be given to people with early symptoms and to high-risk contacts, such as frontline healthcare workers, to save lives. The International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh, is already studying about 50 survivors of Nipah.

According to Gavi, the vaccine alliance, several candidate vaccines for Nipah are in clinical trials, including one based on messenger RNA, one based on a viral vector, and one containing the protein subunit of Hendra virus, which closely resembles Nipah.

Because Nipah is an RNA virus that is prone to mutate, studying the virological factors contributing to severity is important for monitoring its pandemic potential. It is also crucial to study variation in immunological mechanisms known to affect people’s susceptibility to Nipah, the article adds.