A killer amoeba that lurks in freshwater lakes and unchlorinated swimming pools, attacking swimmers' brains, has claimed the lives of at least 138 people worldwide over the last two decades, researchers said.
The microscopic organism, which prefers bodies of water that reach surface temperatures of at least 95 degrees, first came to light 22 years ago in Australia. Since then, it has claimed 55 lives in the United States, said Dr. Julio Martinez, a neuropathologist at Presbyterian-University Hospital in Pittsburgh.
Most people are naturally immune to the amoebas, called naegleria fowleri, he said. But if the single-cell organisms attack the brain, death is almost certain.
The organisms are found in swimming pools and natural bodies of freshwater around the world, Martinez said. They can enter a swimmer's body through his nose and cause a disease called amoebic meningoencephalitis, which destroys the brain.