Wikipedia
Naegleriasis, also known as primary amoebic meningoencephalitis (PAM), amebic encephalitis, and naegleria infection, is an infection of the brain by the free-living protist Naegleria fowleri, also known as the "brain-eating amoeba". The term "brain-eating amoeba" has also been applied to Balamuthia mandrillaris, causing some confusion between the two, however Balamuthia mandrillaris is unrelated to Naegleria fowleri, and causes a different disease called granulomatous amoebic encephalitis, and unlike Naegleriasis, which is usually seen in people with normal immune function, granulomatous amoebic encephalitis is usually seen in people with poor immune function such as those with HIV/AIDS or leukemia.
N. fowleri is typically found in warm bodies of fresh water, such as ponds, lakes, rivers, and hot springs. It is also found in soil, poorly maintained municipal water supplies, water heaters, near warm-water discharges of industrial plants, and in poorly chlorinated, or unchlorinated swimming pools, in an amoeboid or temporary flagellate stage. There is no evidence of it living in salt water.
Although infection occurs rarely, it nearly always results in death, with a case fatality rate greater than 95%.