Since May 2018 when Kerala reported the first Nipah outbreak in Kozhikode district, there have been three more outbreaks of Nipah virus including the latest one in late-August 2023. For reasons still not known, three of the four Nipah outbreaks in Kerala in 2018, 2021 and 2023 have been in Kozhikode district; the 2019 outbreak was in Ernakulam district.
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Even five years after the first outbreak in Kerala, and four outbreaks in all, it is still unclear why three of the four outbreaks have been in Kozhikode district in Kerala. Fruit bats that can cause Nipah virus outbreaks in humans are not restricted to Kozhikode district.