A person with an acanthamoeba infection has a parasitic infection of the eye or brain, caused by an amoeba. Amoebas are tiny, single celled organisms that are present in soil and water. Acanthamoeba can enter the skin through a cut, wound, or through the nostrils.

Infection of the brain is very rare. Eye infections occur in about 1 out of 10,000 people who wear contact lenses.