"Though infections tend to be found in southern states, Naegleria lives almost everywhere in lakes, hot springs, even dirty swimming pools, grazing off algae and bacteria in the sediment.

Beach said people become infected when they wade through shallow water and stir up the bottom. If someone allows water to shoot up the nose - say, by doing a somersault in chest-deep water - the amoeba can latch onto the olfactory nerve. "