Symptoms of Acanthamoeba keratitis include the following: Sensitivity to light and excessive tearing. Blurred vision with eye redness and pain. Sensations of having something in your eye.

Because these amoebae have the ability to exist as free-living organisms in nature and only occasionally invade a host and live as parasites within host tissue, they have also been called amphizoic amoebae (Page, 1988). All three amoebae cause infections of the central nervous system (CNS).

Free-living amoebae (FLA) are found in soil and water habitats throughout the world. These amoebae ingest bacteria, yeast, and other organisms as a food source. Unlike “true” parasites, pathogenic FLA can complete their life cycles in the environment without entering a human or animal host.

There are numerous parasitic amoebas. Of six species found in the human alimentary tract, Entamoeba histolytica causes amebic dysentery.

Acanthamoeba is a microscopic, free-living ameba, or amoeba* (single-celled living organism), that can cause rare**, but severe infections of the eye, skin, and central nervous system. The ameba is found worldwide in the environment in water and soil.

These infections usually occur in people with compromised immune systems. Who is at risk for infection with Acanthamoeba? Acanthamoeba keratitis is most common in people who wear contact lenses, but anyone can develop the infection.

Acanthamoeba can be found in dust, soil, seawater, freshwater (including rivers, lakes, unchlorinated pools and farm dams), tap water, bottled water, and chlorinated spas and swimming pools.

The common manifestations of Acanthamoeba infections in man are granulomatous encephalitis, keratitis and cutaneous lesions. [7] Acanthamoeba spp. is also known to cause chronic meningitis.

The mode of transmission includes inhalation of cysts and trophozoites carried by the wind through the respiratory tract, improper contact lens-care practices, or direct skin contact by traumatic injection or entry through preexisting wounds or lesions.

Case studies show that the Acanthamoeba keratitis is successfully treated in the person having the contact lens using six month therapy with topical Miconazole, Metronidazole, Prednisolone and neomycin as well as oral ketokonazole.

Unlike N. fowleri, Acanthamoeba has only two stages, cysts (1) and trophozoites (2), 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) (3).

Naegleria fowleri infects people when water containing the ameba enters the body through the nose. This typically occurs when people go swimming or diving in warm freshwater places, like lakes and rivers. The Naegleria fowleri ameba then travels up the nose to the brain where it destroys the brain tissue.