Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 35-08: Infections with Pathogenic Free-Living Amoebas + Key Features Download Section PDF Listen +++ +++ Essentials of Diagnosis ++ A fulminating, hemorrhagic, necrotizing meningoencephalitis Occurs in healthy children and young adults and is rapidly fatal +++ General Considerations ++ Caused by free-living amoebae Naegleria fowleri (most commonly) Balamuthia mandrillaris Acanthamoeba species The incubation period varies from 2 to 15 days +++ Demographics ++ N fowleri is a thermophilic organism found in Fresh and polluted warm lake water Domestic water supplies Swimming pools Thermal water Sewers Most patients give a history of exposure to warm fresh water + Clinical Findings Download Section PDF Listen +++ +++ Symptoms and Signs ++ Early symptoms include headache, fever, stiff neck, and lethargy, often associated with rhinitis and pharyngitis Vomiting, disorientation, and other signs of meningoencephalitis develop within 1 or 2 days, followed by coma and then death within 7–10 days +++ Differential Diagnosis ++ No distinctive clinical features distinguish the infection from acute bacterial meningoencephalitis + Diagnosis Download Section PDF Listen +++ +++ Laboratory Tests ++ Cerebrospinal fluid (CSF) shows hundred to thousands of leukocytes and erythrocytes per cubic millimeter Protein is usually elevated, and glucose is normal or moderately reduced A fresh wet mount of the CSF may show motile trophozoites Staining with Giemsa or Wright stain will identify trophozoites Species identification is based on morphology and immunologic methods + Treatment Download Section PDF Listen +++ +++ Medications ++ Amphotericin B is drug of choice Four survivors in North America were treated with amphotericin B, rifampin, and other agents + Outcome Download Section PDF Listen +++ +++ Prognosis ++ Nearly always fatal +++ When to Admit ++ All patients with confirmed or suspected disease + Reference Download Section PDF Listen +++ + +Jahangeer M et al. Naegleria fowleri: sources of infection, pathophysiology, diagnosis, and management; a review. Clin Exp Pharmacol Physiol. 2020 Feb;47(2):199–212. [PubMed: 31612525]