Naegleria fowleri

Overvew
  • Naegleria and acanthamoeba are free-living amoeba which exist in water and moist environments. Although many are exposed to these organisms, infection is rare. However, when it does occur the clinical consequence is a potentially-life-threatening meningoencephalitis.
Pathogenesis
  • Inoculation with Naegleria occurs through aspiration of contaminated water. The amoeba invade through the cribiform plate and establish a growing infection within the olfactory epithelium. Subsequent spread throughout the CNS and meninges, resulting in meningoencephalitis, is almost always fatal.
Clinical Consequences
  • Patients present with intense headache and fever along with meningismus and focal neurological impairments. Eventually, seizures and coma result followed by death.
Laboratory
  • Examination of the CSF will reveal a neutrophilic CSF pleocytosis, reduced CSF glucose, and elevated CSF protein. These results would normally be indicative of a bacterial meningitis; however, upon gram stain of CSF no bacteria will be present. Instead, ameoba will be visible upon wet mount of CSF.