What Is A Brain-Eating Amoeba?

Earlier this month, a 16-year old girl in Florida contracted a waterborne parasite known as Naegleria fowleri after swimming in a local river. Sadly, the girl developed meningoencephalitis, a severe infection of the brain, and died. The national press has described this parasite as a brain-eating amoeba, due to the characteristic swelling of the brain and destruction of nervous tissue associated with the infection.

Naegleria fowleri is a free-living protozoan that is commonly found in warm freshwater environments, including lakes, rivers and hot springs and may also be found in some groundwater sources. Naegleria, like many parasitic microorganisms, is able to change forms depending on environmental conditions. The three stages/forms include:

- Cysts

- Trophozoites

- Flagellates

The cysts are microscopic resting structures that allow Naegleria to withstand harsh, suboptimal conditions. Flagellates are non-feeding forms of the organism that allow movement. Trophozoites are a feeding and reproductive form of the organism. Naegleria, in this stage, typically feed on bacteria found in water. Trophozoites can infect humans if they are able to enter the nasal cavity, usually through recreational water activities where water goes deep into a person’s nose. Naegleria trophozoites migrate to the brain through nerves and feed extensively on nerve tissue. Eventually a condition known as Primary Amoebic Meningoencephalitis (PAM) develops, in which severe inflammation of the brain occurs. At this stage, coma and death occur quickly.

Despite Naegleria’s prevalence in natural bodies of water found in warm-weather states, infections with this organism are extremely rare. Only a few infections occur annually in the U.S., although most are fatal.

The U.S. EPA has placed Naegleria fowleri on its Contaminant Candidate List for drinking water. Contaminants on this list are under consideration for regulatory action to protect public health.

LEGEND’s Phoenix, Arizona laboratory is one of the few environmental laboratories in the country that test for Naegleria fowleri. LEGEND uses a culture technique for primary isolation of the amoeba followed by an enzyme-linked immunosorbent assay (ELISA) for confirmation. For more information on testing for Naegleria fowleri, please contact LEGEND’s Arizona laboratories.

Sources:

U.S. Centers for Disease Control and Prevention (CDC)

U.S. Environmental Protection Agency (EPA), Contaminant Candidate 3 List