ICMR study identifies well water as major risk factor for amoebic meningoencephalitis in Keralam

A joint study by the Kerala Health Department and the Indian Council of Medical Research National Institute of Epidemiology has identified non-chlorinated well water and exposure to natural water bodies as major risk factors for amoebic meningoencephalitis in Kerala. Published in the US Centers for Disease Control and Prevention journal Emerging Infectious Diseases, the case-control study provides the first epidemiological evidence linking unsafe domestic water use to the rare central nervous system infection in the state.

The research analyzed 159 amoebic meningoencephalitis cases reported in Kerala between January 1 and November 11, 2025. Among the 76 cases confirmed by real-time PCR testing, 67 were caused by Acanthamoeba species, while nine were caused by Naegleria fowleri. The findings show that Acanthamoeba, rather than Naegleria fowleri, accounted for the overwhelming majority of cases, challenging public perception regarding the primary cause of the outbreak. Overall, the state recorded 41 deaths, representing a case fatality rate of 25.8 percent.

Investigators found that individuals using non-chlorinated well water for bathing or face washing faced nearly three times higher odds of contracting Acanthamoeba-related amoebic meningoencephalitis. The estimated population attributable fraction was 34.2 percent, indicating that over one-third of population cases could be prevented by eliminating non-chlorinated well water exposures.

Dr. R. Aravind, Head of Infectious Diseases at Thiruvananthapuram Government Medical College and a key researcher on the study, emphasized the public health relevance for Kerala, where a large portion of the population relies on private or public wells rather than chlorinated piped water systems. Domestic water exposures cited in the study involved direct physical contact, such as bathing or washing the face and hair, rather than water ingestion. Poorly maintained wells contaminated by heavy rainfall, flooding, sewage, or organic runoff create ideal environments for free-living amoebae.

The study also revealed that swimming or diving in natural water bodies like ponds and canals increased infection odds by 4.7 times, particularly among individuals with a history of facial injuries or nasal surgery. Entering natural water bodies with open skin wounds or ulcers presented the strongest association, raising infection odds by 25.4 times due to Acanthamoeba entering through broken skin.

Researchers highlighted lower socioeconomic status as a significant contributing factor, as vulnerable households often lack access to safe treated water and rely on unchlorinated wells. Experts recommend year-round water surveillance, periodic well chlorination by local self-governments, and targeted public health messaging ahead of monsoon seasons to mitigate transmission risks.

#AmoebicMeningoencephalitis #Kerala #ICMR #PublicHealth #Acanthamoeba #WaterQuality #DrRAravind