Brain-Eating Amoeba Strikes in Summer
Six Deaths in 2007 From Amoeba in Warm Fresh Water
Brain-Eating Amoeba Not on the Rise
Last summer's six cases were a lot compared to most years. But the CDC says there's no evidence that the brain-eating amoeba is on the rise. There were eight cases in 1980, seven cases in 2002, and six cases in 1978, 1986, and in 1995. Since 1937, there have been only 121 known cases.
So far, there haven't been any cases in 2008. But the CDC warns people either to avoid swimming in warm, fresh water or to wear nose plugs if they do. N. fowleri does not live in salt water or in properly maintained swimming pools, although it has been found in domestic water supplies.
"People should assume there is a risk of swimming in warm, fresh water," Yoder says. "And we think that things people do to minimize entry of water into the nose might provide some reduction of risk, such as using a nose clip. We can't say there is scientific evidence this works, but that is a commonsense approach."
The CDC also suggests that people avoid digging or stirring up sediment while playing or working in warm waters. The CDC further suggests that people avoid thermally polluted water, such as the water near power plants, although Yoder says the CDC has not yet looked at how much thermal pollution affects amoeba populations in public waters.
States where N. fowleri has caused disease include Arkansas, Arizona, California, Florida, Georgia, Louisiana, Missouri, Mississippi, North Carolina, New Mexico, Nevada, Oklahoma, South Carolina, Texas, and Virginia.
Infections have been seen around the world, including 16 cases traced to the same swimming pool in the Czech Republic.
There's no question of eradicating the blob. N. fowleri turns into its cyst form when conditions aren't right -- and can survive for years in the soil.
The CDC reports details of the six 2007 cases, and analyzes PAM trends, in the May 30 issue of Morbidity and Mortality Weekly Report.