Global Review on Naegleria fowleri Cases: Contemporary Epidemiology, Diagnosis, Treatment and Outcomes

Background/Objectives: Primary amoebic meningoencephalitis (PAM) is a rare, fulminant, and often fatal central nervous system infection caused by the opportunistic free-living amoeba Naegleria fowleri. Although Naegleria species are widely present in freshwater and soil worldwide, human disease is associated specifically with pathogenic N. fowleri rather than the many nonpathogenic environmental species, and virulence may vary across N. fowleri isolates. This systematic review aimed to synthesize contemporary global data from 2000 to 2024 to identify recent trends in epidemiology, clinical presentation, diagnosis, treatment, and outcomes. Methods: A systematic literature search was conducted across PubMed, Scopus, and the Cochrane Library, identifying 58 eligible publications encompassing 66 individual cases. Results: Most reports originated from the United States, India, and China. The median patient age was 14 years, with 78% of cases occurring in males. Annual case reports increased from one per year (2000–2005) to over four per year (2020–2024), reflecting either a true rise in incidence or improved detection. Common presenting symptoms included fever, headache, and altered mental status. Diagnosis was confirmed via polymerase chain reaction (PCR) testing or post-mortem biopsy in nearly one-third of cases. Treatment regimens varied, with amphotericin B and miltefosine being the most frequently used agents. Overall mortality was 83%, with survival strongly associated with early initiation of combination therapy. Pediatric patients had a higher survival rate (22%) compared to adults (7.1%). Conclusions: The findings highlight the need for heightened clinical awareness, especially in the context of climate-driven ecological changes that may expand N. fowleri’s geographic range. This review underscores critical gaps in surveillance and diagnostics and emphasizes the importance of a One Health approach to addressing emerging threats like PAM. Further research into novel therapeutics, rapid diagnostics, and global case reporting systems is urgently needed.