(Diagram of Acanthamoeba astromyxis life cycle.)
Acanthamoeba astromyxis is a genus of amoebae, one of the most common protozoa found in soil fresh water, pools, heating and cooling units, sewage systems and tap water.  This parasite is capable of causing several infections in the human body.  Acanthamoeba keratitis, is an infection of the eye that can result in permanent visual alteration or blindness.  Granulomatous Amebic Enchephalitis, is a serious infection of the central nervous system affecting the brain and spinal cord.  A disseminated infection that is widespread that affects the skin, sinuses, lungs and other organs singly or by themself.  

Keratitis symptoms include, eye pain, eye redness, blurred vision, sensitivity to light, a sensation of an object in the eye, and excessive tearing.  

Granulomatous Amebic Encephalitis symptoms include, mental status changes, loss of coordination, fever, muscular weakness or partial paralysis affecting one side of the body, double vision, sensitivity to light and other neurological problems. 

Acanthamoeba has only two stages in its life cycle, cysts and trophozoites.  The later is the infected form which replicates by mitosis or cell division.  Entry to the human form can be attained through the eye, nasal passages to the lower respiratory tract, or through uncerated or broken skin.  See diagram below.

The geographic distribution of this parasite appears to occur worldwide.