THIRUVANANTHAPURAM: As the state grapples with its sixth Nipah virus (NiV) outbreak, and the second one this year, there is still a lack of comprehensive understanding regarding effective prevention methods. While it is agreed that fruit bats of a specific variety are responsible for spreading the virus, the exact reasons behind its localised impact and human transmission remain unclear.
Kozhikode has experienced Nipah outbreaks in 2018, 2021, and 2023. Malappuram reported cases in 2018 and again in July and September this year. Ernakulam recorded a single case in 2019. Investigations are complicated by the fact that all primary cases have resulted in death, except for the Ernakulam outbreak.
Despite directives from the government to conduct extensive surveillance in Kozhikode to understand the virus’s persistence since September last year, there has not been much headway.
While the health department’s efforts to contain Nipah were seen as a success, the World Health Organisation pointed out that there was a missed opportunity to collect timely and accurate data to better understand the epidemiology, clinical, and virological characteristics of NiV and to introduce emergency-driven clinical trials for potential treatments. The delay happened despite the fact that NiV was identified as one of the top eight emerging pathogens by the WHO.
“Understanding the connection between animal reservoirs and human infections is essential for developing better preventive measures,” said Dr Althaf A, a public health expert and professor at the Government Medical College in Thiruvananthapuram. He stressed the importance of tracing the link between animal and human transmission to create effective prevention strategies.
Though little has been learned from past outbreaks, there is growing suspicion that environmental factors play a role. Understanding the disease’s root cause requires a deeper examination of wildlife and their habitats. Fruit bats, particularly Pteropus species, are known reservoirs for the Nipah virus, but the exact transmission mechanism to humans is still not well understood.
A study by the Indian Council of Medical Research (ICMR) detected Nipah virus antibodies in bats from Kozhikode, Malappuram, and Wayanad. “There are bats everywhere, and many areas in Kerala have environmental conditions similar to Kozhikode, such as mangroves and urban forests. We need to investigate whether specific bat colonies harbour more viruses and why factors like food scarcity and overcrowding among bats can increase viral shedding,” said Dr S Nandakumar, assistant director of the animal husbandry department.
The government started the Kerala One Health Centre for Nipah Research in Medical College in Kozhikode last year. The institute has made progress in coordinating with various departments including, health, animal husbandry and the local bodies. However, wildlife biologists feel that progress has been insufficient. “Nipah is still viewed primarily as a medical issue, but the solution lies in basic research,” said one scientist.