By Chris Healey
One of the most deadly known organisms on Earth could be lurking in a lake or freshwater source you’ll visit this summer.
Naegleria fowleri is a free-living amoeboflagellate found in warm bodies of water such as ponds, lakes, hot springs, and coastal waters. It is also found in soil, minimally-chlorinated swimming pools, industrial plant water discharge, and water heaters. N. fowleri grows best at temperatures up to 115 degrees Fahrenheit, and survives temperatures in excess of 115 degrees Fahrenheit for a short time.
N. fowleri causes primary amebic meningoencephalitis (PAM), an infection of the central nervous system characterized by brain destruction. The amoeba consumes brain tissue.
PAM occurs when N. fowleri enters the body through the nasal passages, typically when swimming or diving in contaminated freshwater. Once entered through the nose, the amoeba travels to the brain. Early symptoms of PAM are similar to bacterial meningitis and may begin approximately five days after infection. Initial symptoms include headache, fever, nausea and vomiting. Later, symptoms can include stiff neck, confusion, lack of attention to people and surroundings, loss of balance, seizures, and hallucinations. After onset of initial symptoms, the disease rapidly progresses. Death invariably occurs approximately five days after onset of symptoms.
The fatality rate for an infected person is over 99%. Only 1 out of 128 known infected individuals in the United States between 1962 to 2012 survived infection. In 2011, a 9-year-old child in central Virginia died from the disease.
It is important to note you cannot become infected with N. fowleri by drinking contaminated water. Infection can only occur if ameba-contaminated water enters nasal passageways.
Precautions can be taken to reduce the risk of infection. Avoid swimming in bodies of freshwater during high-water temperatures and low-water levels. Also, refrain from digging in, or stirring up, sediment in shallow areas of freshwater bodies. Those planning on swimming in freshwater lakes should wear a nose plug, hold their nose before diving, or avoid submerging their head. Another effective method is to keep your head above water in freshwater, hot springs, or untreated thermal waters.
A novel infection route involving nasal irrigation was recently reported by the CDC. Those who use a neti-pot, or other nasal irrigation devices, should use discretion when filling their devices. Water should be boiled for one minute, passed through a 1-micron sized filter, and distilled or sterilized before nasal irrigation use.
(Image Credit: B A Bowen Photography, c/o Wikimedia Commons)