Scientists identify four Nipah positive bat species in India

LIVE MINT

JUNE 30, 2019

NEETU CHANDRA SHARMA

Scientists have flagged four new bat species as surveillance priorities in India after the re-emergence of Nipah Virus outbreak in 2018 in Kerala.

In a new study, published in PLoS Neglected Tropical Diseases on Thursday, scientists used machine learning to identify bat species with the potential to host Nipah virus, with a focus on India. A team of scientists used machine learning, a form of artificial intelligence to flag bat species with the potential to harbour Nipah.

Scientists compiled published data on bat species known to carry Nipah and other henipaviruses (bat borne viruses) globally. Data included 48 traits of 523 bat species, including information on foraging methods, diet, migration behaviors, geographic ranges, and reproduction. They also looked at the environmental conditions in which reported spillovers occurred. After compilation of data, the scientists applied a trait-based machine learning approach to a subset of species that occur in Asia, Australia, and Oceana.

Their algorithm identified known Nipah-positive bat species with 83% accuracy. It also identified six bat species that occur in Asia, Australia, and Oceana that have traits that could make them competent hosts and should be prioritized for surveillance. Four of these species occur in India, two of which are found in Kerala.

“The scientists identified six species with geographic ranges overlapping Asia, Australia, and Oceana that are not currently identified as Nipah reservoirs but, on the basis of trait similarity with known Nipah virus- virological-positive bat species, have high likelihood of exposure to Nipah virus i.e. Rousettus aegyptiacus, Taphozous longimanus, Taphozous melanopogon, Rhinolophus luctus, Chaerophon plicatus, and Macroglossus minimus," the study said.

“The geographic ranges of four of these species overlap with India: C. plicatus, R. luctus, T. longimanus, and T. melanopogon. The latter two species overlap with Kerala, with probabilities of Nipah virus-positivity around 80%," it said.

“There are likely many competent Nipah hosts that have not been identified. There is a need to devise new methods that take all available data into account to guide sampling efforts in India and in other regions. By looking at the traits of bat species known to carry Nipah globally, our model was able to make predictions about additional bat species residing in India with the potential to carry the virus and transmit it to people. These bats are currently not on the public health radar and are worthy of additional study," said Barbara Han, a disease ecologist at Cary Institute of Ecosystem Studies, New York, USA and co-lead author of the paper.

India is home to an estimated 113 bat species. Just 31 of these species have been sampled for Nipah virus, with 11 found to have antibodies that signal host potential. “Given the role bats play in transmitting viruses infectious to people, investment in understanding these animals has been low. The last comprehensive and systematic taxonomic study on the bats in India was conducted more than a century ago. We set out to make trait-based predictions of likely henipavirus reservoirs near Kerala," said Raina K. Plowright, a disease ecologist at Montana State University, and co-lead author of the study.

Since its discovery in 1999, Nipah virus has been reported almost yearly in Southeast Asia, with Bangladesh and India being the hardest hit. Nipah virus is a highly lethal, emerging henipavirus that can be transmitted to people from the body fluids of infected bats.

Eating fruit or drinking date palm sap that has been contaminated by bats has been flagged as a transmission pathway. Once infected, people can spread the virus directly to other people, sparking an outbreak. Domestic pigs are also bridging hosts that can infect people. There is no vaccine and the virus has a high mortality rate.

The scientists said that their predictions must be combined with local knowledge on bat ecology – including distribution, abundance, and proximity to humans – to design sampling plans that can effectively identify bat hosts that pose a risk to humans. The research though not definitive list of reservoirs, may prove as a guide for early surveillance.

“Surveilling high-risk bat populations can provide early warning for veterinarians and public health authorities to take preventative measures needed to preempt an outbreak. Identifying which species harbor disease is an important first step in surveillance planning," Han said.

The research was funded by the National Science Foundation’s Ecology and Evolution of Infectious Diseases (EEID) program, the Defense Advanced Research Projects Agency’s PREventing EMerging Pathogenic Threats (PREEMPT) program, and the National Institutes of Health’s National Institute of General Medical Sciences.

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