A Case-Based Review of Free-living Amebic Human Infections and Diagnosis

Naegleria fowleri, Balamuthia mandrillaris, and Acanthamoeba species are free-living amebae that are ubiquitously found in soil and water and can opportunistically cause invasive, deadly infections in humans. In this review, we present four patient cases due to free-living amebae and review the epidemiology and clinical significance of the diseases they cause. Specifically, primary amebic encephalitis due to N. fowleri, granulomatous amebic encephalitis due to B. mandrillaris and Acanthamoeba spp., keratitis due to Acanthamoeba spp., and non-central nervous system systemic infections (due to B. mandrillaris and Acanthamoeba spp.) are reviewed, and the clinical utility of microbiologic and histopathologic methods for diagnosing infections due to free-living amebae are compared.