Acanthamoeba is a type of amoeba that lives in the environment, in the soil, in fresh water and in other habitats. Acanthamoeba rarely causes infections but when it does cause infection, however, it can be extremely serious. Diseases caused by Acanthamoeba include amoebic keratitis and encephalitis. Encephalitis is caused by Acanthamoeba entering cuts and spreading to the central nervous system. Amoebic keratitis is a rare disease where the amoebae (Acanthamoeba) invade the cornea of the eye. Recently, there have been multiple reports of increasing incidence of Acanthamoeba keratitis especially among contact lens wearers.

Further reading: Acanthamoeba: Biology and Pathogenesis
See also: Acanthamoeba pictures, illustrations and figures