2. A free-living ameba found in soil, sewage, and water, several species of which cause acanthamebiasis.
3. A genus of free-living soil amoebae that produces no flagellate stage. Its organisms are pathogens for several infections in humans and have been found in the eye, bone, brain, and respiratory tract.
Acanthamoeba occur in brackish water and sea water; as well as, in heating, venting, and air conditioner units, humidifiers, and dialysis units.
They can enter the skin through a cut, wound, or through the nostrils and, once inside the body, can travel to the lungs and through the bloodstream to other parts of the body, especially to the central nervous system (the brain and spinal cord). Through improper storage, handling, and disinfection of contact lenses, acanthamoeba can enter the eye and cause infection there.
A particularly dire infection caused by acanthamoeba called granulomatous amebic encephalitis is characterized by headache, stiff neck, nausea, vomiting, confusion, loss of balance, seizures, and coma that can progress over several weeks and end in death.