Acanthamoeba Life Cycle

Acanthamoeba is a genus of single-celled protozoans which typically live in soil or warm water. They can be responsible for a dangerous form of infection in humans affecting the central nervous system, and usually resulting in the fatality of the host. They can infect humans through exposure to the eye while swimming and wearing contact lenses. Acanthamoeba follow a typical amoeboid life cycle, exhibiting both a cyst stage and a trophozoite stage.

Trophozoite Stage

• Trophozoite means "feeding animal" in Latin, and the word describes the feeding active stage of a protozoan. This stage can be split into two categories to describe different species of protozoa based on whether it has flagella or not. Acanthamoeba exhibit both forms of trophozoite stages depending on the conditions they find themselves in.

Amoeboid Trophozoites

• In the amoeboid stage, the acanthamoeba is able to reproduce via asexual reproduction. The organism undergoes a process called mitosis, in which it clones itself and splits into two identical cells. It is found in this stage where there is available nutrients present for it to feed on. This form is usually the infectious stage, although the organism will often first enter the body while in the cyst stage.

Flagellated Trophozoite

• The amoeboid trophozoite changes to a flagellated form in order to become more mobile to find food. It does not reproduce during this stage, and will remain here until conditions become good enough to switch back to an amoeboid stage, or bad enough to switch to a cyst stage. Acanthamoeba are distinguishable from similar protozoa by their spike-shaped pseudopodia, or false feet, in this stage. The most similar genus of protozoa to acanthamoeba are naegleria, which have blunt pseudopodia.

Cyst Stage

• The cyst stage of acanthamoeba is a protective stage in which the organism can avoid desiccation. Acanthamoeba have double-walled cysts and look wrinkly. The organism is dormant in this stage, and will stay this way until conditions improve enough to switch back to a trophozoite stage.

Diseases

• Infections attributed to acanthamoeba are granulomatous amebic encephalitis (GAE) and amebic keratitis. GAE can enter the body through a skin lesion that is infected or possibly through the nose. It then travels along the outside of blood vessels until it reaches the central nervous system. At this point, it is often fatal. Amebic keratitis is usually caused by wearing contact lenses while swimming in infected waters, or using contaminated contact lens solution. It will threaten your vision if you are infected, but will not likely affect your overall immune system or be fatal.