A brain amoeba responsible for three deaths so far this summer is likely to multiply in warm freshwater ponds and lakes, and appears to prefer the warm climate of the Southern states. And while a Naegleria fowleri infection -- or any amoeba infection, for that matter -- is extremely rare, it is also extremely lethal: A human who contracts an infection has only a 5% chance of survival.

Nearly two-thirds of those killed by the amoeba are children under the age of 13, CNN reports. So far in 2011, the amoeba has killed three people in the U.S.: Most recently, a 16 year old girl from Brevard County, Fla., who died on Saturday after contracting an infection while swimming in St. John's River.

Courtney Nash began suffering from headache, stiffness, fever and nausea sometime after swimming in the river on Aug. 3. Doctors at Arnold Palmer Hospital in Orlando, Fla. performed a spinal tap and diagnosed her with primary amoebic meningoencephalitis.

Christian Alexander Strickland, 9, of Henrico County, Va. died on Aug. 5 of primary amoebic meningoencephalitis, although in his case it is not certain where he came into contact with Naegleria fowleri.

His mother, Amber Strickland, told The Richmond Times-Dispatch she believes Christian may have ingested contaminated water when he was dunked at a day camp run by the Richmond-based Virginia Fishing Adventures the week before he died.

The CDC confirmed another death in June in Louisiana, but provided no further details.

Three deaths a year from the deadly amoeba is about average. More than 100 people have died from amoebas in the U.S. since 1962.

Health official told WFTV Channel 9, a local Florida station, that fatal amoeba infections almost always happen in the summer and only in freshwater lakes and ponds where water is above 80 degrees.

Jeremy Lewis's son Kyle died from an infection last summer, after contracting an amoeba while swimming in a pond with his family.  Lewis and his wife formed the Kyle Lewis Amoeba Awareness Foundation to help spread the word about the dangers of swimming in warm fresh water ponds, lake, and rivers.

WFTV published The Brevard County Health Department's recommendations for preventing an amoeba infection:

--Don't swim or jump into warm, stagnant, fresh water, such as ponds or warm water discharge pools, or non-chlorinated swimming pools.

--Don't swim in polluted water.

--Don't swim in areas posted as "No Swimming."

--Hold your nose, or use nose plugs when jumping or diving into water. (People become infected when they ingest the amoeba.)

"Prevention is the only thing you have," Lewis told the Richmond Times-Dispatch. "As a father who lost a child, I'm asking, why didn't I know about this?"