With the State appearing to have seen off another wave of Nipah, veterinary epidemiologists have called for a systematic approach in tracing the cause of such bouts.
While the recurrence of the zoonotic disease in Kozhikode continues to baffle the scientific community, there are calls to identify hotspots of roost trees frequented by fruit bats to minimise anthropogenic activities in such areas.
Nandakumar S. Nair, Disease Investigation Officer, State Institute for Animal Diseases, who has been part of teams deployed to the affected areas to trace the sources of all four Nipah outbreaks reported in Kerala since 2018, emphasised the need to identify hotspots of bat roosts that harbour the Nipah virus (NiV). Fruit bats (or flying foxes that belong to the pteropus genus of megabats) are reservoirs of the virus.
Bats are known to respond to stress caused by overcrowding and displacement due to habitat loss by increasing the production and shedding of viruses. These are considered among the most notorious zoonoses that spill over from wildlife into domestic animals and humans.
“As part of measures aimed at controlling the NiV spread, we could collect blood samples and guano (bat droppings) for disease detection and limit human activity in such areas. Caution should also be exercised while consuming fruits harvested in such areas,” Dr. Nandakumar said.
Lamenting the absence of an effective mechanism for data sharing among departments and agencies, officials also called for imbibing the spirit of the One Health concept to find collaborative solutions.
Unlike the NiV outbreak that had taken place in Malaysia in 1998 and 1999 where the virus spread through pigs, the zoonotic spillover in Kerala had taken place in the absence of a transmission host. While Bangladesh too had reported direct transmission of the virus hypothetically through consumption of contaminated date palm sap, studies in Kerala have been unable to identify the medium of the spread.
Samples of animals, including pigs, cattle, including cows and goats, cats, and carcasses of a horse and several bats have been sent to the National Institute of High Security Animal Diseases in Bhopal in a bid to identify the possible host of the disease transmission.
