Deepak Y Patil, Rima R. Sahay, Sreelekshmy Mohandas, Pragya D. Yadav
Nipah virus (NiV), a highly infectious human pathogen, is primarily maintained in Pteropus bats. The virus was initially identified in a large outbreak in Malaysia in 1998–1999 1 . Since then, it has caused repeated spillover events in South and Southeast Asia, with high case fatality rates and lacks effective treatment options 2 . The history of the Nipah virus disease in India is unique: although its bat reservoir is widely distributed across the country, human cases have only been reported repeatedly in two states, namely, West Bengal in Eastern India and Kerala in the southwest coast 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 . These two geographies are very different in terms of ecology, demography, health system capacity and human environment interface, but both have observed Nipah spillover recurrence. Outbreaks were reported in West Bengal in 2001 and 2007, epidemiologically associated with Bangladesh 3 , 4 , and again in 2026, when two healthcare workers in Barasat, North 24 Parganas district were laboratory-confirmed for Nipah virus infection 11 . Kerala, on the other hand, has had recurring spill-over events since 2018, with outbreaks in 2019, 2021, 2023, 2024, and 2025, and has frequently been limited to single cases or small outbreaks with quick containment 5 , 6 , 7 , 8 , 9 , 10 . This commentary argues that recurrent Nipah virus spill over in India is best understood not as a uniform virological phenomenon, but as the outcome of distinct ecological interfaces interacting with bat reservoir dynamics, human exposure patterns, and health system preparedness. A comparative analysis of West Bengal and Kerala states outbreaks reveals how the same virus can generate divergent epidemiological narratives depending on geography.