Acanthamoeba the Clickroach

Free-living amebae belonging to the genera Acanthamoeba, Balamuthia, Naegleria and Sappinia are rare causes of disease in humans and animals.

Acanthamoeba spp. and Balamuthia mandrillaris are free-living amebae capable of causing granulomatous amebic encephalitis (GAE). Acanthamoeba is an important cause of severe keratitis among contact lens wearers and may also cause cutaneous lesions, particularly in immunocompromised individuals. Because species level identification is not typically performed on Acanthamoeba cases, the full range of pathogenic species within the genus is not known, but species known to infect humans include A. byersi, A. castellanii, A. culbertsoni, A. hatchetti, A. healyi, A. astroonyxix, A. divionensis and A. polyphaga. B. mandrillaris may also occur in association with skin lesions. Naegleria fowleri produces an acute, and usually lethal, central nervous system (CNS) disease called primary amebic meningoencephalitis (PAM). Sappinia pedata has been implicated in one human case of amebic encephalitis.