Life Cycle of Acanthamoeba spp.:

Acanthamoeba spp. have been found in soil; fresh, brackish, and sea water; sewage; swimming pools; contact lens equipment; medicinal pools; dental treatment units; dialysis machines; heating, ventilating, and air conditioning systems; mammalian cell cultures; vegetables; human nostrils and throats; and human and animal brain, skin, and lung tissues.  Unlike N. fowleri, Acanthamoeba has only two stages, cysts and trophozoites , in its life cycle.  No flagellated stage exists as part of the life cycle.  The trophozoites replicate by mitosis (nuclear membrane does not remain intact) .  The trophozoites are the infective forms, although both cysts and trophozoites gain entry into the body through various means.  Entry can occur through the eye , the nasal passages to the lower respiratory tract , or ulcerated or broken skin .  When Acanthamoeba spp. enters the eye it can cause severe keratitis in otherwise healthy individuals, particularly contact lens users .  When it enters the respiratory system or through the skin, it can invade the central nervous system by hematogenous dissemination causing granulomatous amebic encephalitis (GAE) or disseminated disease , or skin lesions in individuals with compromised immune systems.  Acanthamoeba spp. cysts and trophozoites are found in tissue.