Janette DeFelice
Objective: Naegleria fowleri, known as the brain-eating amoeba, is a thermophilic, freshwater amoeba causing primary amoebic meningoencephalitis (PAM), a disease that progresses rapidly from symptom onset to death. Climate change is causing surface water temperatures to increase, providing a hospitable environment for N. fowleri, possibly increasing risk factors for PAM. This review synthesizes the peer-reviewed biomedical literature published between January 2012 and December 2025, examining the risk of N. fowleri infection in the context of a warming climate. Methods: A scoping review was conducted searching PubMed, Scopus, and Environment Complete. Data were extracted using a structured coding framework, and risk dimensions were derived inductively during the coding process. Results: Twenty-seven articles met inclusion criteria. Analysis revealed four dimensions of risk (environmental, behavioral, clinical/biological, and infrastructural). The environmental risk dimension highlighted gaps in understanding geographic range expansion and organism ecology. The behavioral dimension identified recreational water exposure, sinus rinsing, and travel as primary risk drivers. The clinical/biological dimension highlighted the need for standards and capacity in diagnosis and treatment, as well as research into pathogenicity. The infrastructural dimension identified gaps in water distribution system surveillance and disinfectant efficacy at high temperatures. Discussion: This review maps environmental, behavioral, clinical/biological, and infrastructural dimensions of N. fowleri disease risk onto a hazard/exposure/vulnerability framework, highlighting major gaps surrounding exposure and vulnerability. Uncertainties remain in hazard habitat favorability factors, human behavior, and water distribution systems. Emphasis should be placed on characterizing the hazard through environmental testing and determining geographic range, and addressing vulnerability by increasing clinician awareness, which serves double duty in both initiating early empiric treatment and efforts to quantify true disease burden.