Primary Amoebic Meningoencephalitis: A Global Health Threat or Localized Problem

Abstract

Introduction: Amoebic encephalitis is a rare and potentially fatal central nervous system infection caused by free-living amoebae found in freshwater sources, such as lakes and rivers. There are two types of amoebic encephalitis, namely primary amoebic meningoencephalitis (PAM) and granulomatous amoebic encephalitis (GAE). Primary amoebic meningoencephalitis (PAM) is a disease typically caused by infection with Naegleria fowleri, a microscopic amoeba commonly referred to as a “brain-eating amoeba.” This infection destroys brain tissue, causing severe brain swelling and death in most cases. PAM is rare and usually occurs in otherwise healthy children, teens, and young adults. The initial symptoms of PAM are indistinguishable from those of bacterial meningitis, while the symptoms of GAE can mimic a brain abscess, encephalitis, or meningitis. These infections are almost uniformly fatal, with only a few reported survivors globally.

Materials and Methods: This review synthesized clinical, epidemiological, and laboratory findings from global literature on N. fowleri infections. Analysis encompassed the pathogen’s morphological life stages (trophozoite, flagellate, cyst), environmental drivers, mechanisms of neuroinvasion, and regional disease burdens across major affected countries (including the United States, Pakistan, Australia, and India). Diagnostic standards—such as direct cerebrospinal fluid (CSF) wet-mount microscopy, special staining (Giemsa/trichrome), molecular assays (PCR), and culture methods—were evaluated alongside current multidrug treatment regimens.

Results: N. fowleri flourishes in warm freshwater (up to 45.8 degree C). Infection typically occurs in healthy young individuals (median age 14; almost equal to 75% male) during water recreation. Upon entering the nasal cavity, trophozoites traverse the cribriform plate into the olfactory bulb, producing necrosis, micro-hemorrhages, and fatal cerebral edema. Globally, fewer than 500 cases have been documented, with only 11 confirmed survivors. While US cases remain low (0–8 annually), acute regional spikes have been observed, notably in Kerala, India, which reported 69 confirmed cases and 19 deaths late in 2025. CSF wet-mount identification of motile trophozoites and PCR assays remain primary diagnostic tools. Successful clinical management relies on prompt combination antimicrobial therapy—primarily intravenous/intrathecal Amphotericin B, Miltefosine, azole antifungals, and targeted intracranial pressure management—initiated prior to extensive neurological destruction.

Discussion: The rising frequency of PAM in warming climates highlights its transition from an obscure tropical entity to a significant public health concern. Because the therapeutic window is extremely brief (frequently under 5 days from symptom onset), high clinical suspicion in endemic areas is vital to reduce initial misdiagnosis. Proposed clinical staging models (Nasal, Olfactory, and Meningoencephalitic phases) offer a framework for early intervention before irreversible CNS trauma occurs. Given the absence of targeted vaccines or definitive monotherapies, public health interventions—including public safety campaigns, nose-clip utilization during recreational swimming, and strict chlorination of municipal and recreational water sources—remain the primary line of defense.

DOI: https://doi.org/10.24321/0019.5138.202656

How to cite this article:
Sharma V, Deshwali Z H. Primary Amoebic Meningoencephalitis: A Global Health
Threat or Localized Problem. J Commun Dis.2026;58(3):209-217.