Are brain-eating parasites on the rise?

Naegleria fowleri in human brain tissue. (CDC.gov)

Most of us have heard of the recent cases of brain-eating parasites. The first involved a 12-year-old girl named Kali Hardig, who contracted the almost-always fatal protozoa Naegleria fowleri at a water park in Arkansas.  At present, she is showing signs of recovery. The second case involved 12-year-old Zachary Reyna, who contracted the protozoa when he was knee boarding in a shallow Florida gully filled with warm water. Sadly, Zachary was taken off the ventilator yesterday. Both cases of infection involved warm water, which is where Naegleria fowleri thrives.

What is Naegleria fowleri? Popularly known as the “brain-eating parasite,” this single-celled amoeba is found all over the world in warm, fresh water such as lakes, streams, pools, hot springs and warm water discharge from power plants. When water containing this parasite gets into the nose, the amoeba can travel to the brain, where it destroys brain tissue – producing swelling of the brain and death. Drinking water contaminated with the protozoa does not cause disease, nor does bathing or showering. Taking infected water up the nose is the only known route of infection.

Between 2003 and 2012, 31 cases of Naegleria fowleri infection were reported in the United States. All cases were fatal. If young Kali Hardig survives her ordeal with this horrific agent, she will be the second person among 128 in the U.S. to survive infection since 1962.

Typically, symptoms of Naegleria fowleri infection begin to manifest about five days after exposure. Early signs of exposure include headache, fever, nausea and vomiting. These symptoms are usually followed by confusion, stiff neck, loss of balance, hallucinations and seizures. The amoeba causes meningitis, severe infection of the membranes covering the brain and spinal cord. Most cases of exposure have been in Florida and Texas, but now the amoeba is being found in a broader area, as far north as Minnesota and Indiana. Some researchers believe that global warming may account for the northward migration of this formerly southern parasite.

In the June 11th issue of the Journal of Water Health, a disturbing report showed just how prevalent Naegleria fowleri may be. In a study of a Texas reservoir, 67 percent of water samples taken tested positive for the protozoa. While those drinking from the reservoir are in no danger, those who take the reservoir water up the nose are at risk of infection.

Nasal irrigation, such as that involving a neti pot, may be good hygiene, but it is also a direct route to infection by Naegleria fowleri. To avoid a fatal mistake while irrigating your sinuses, be sure that the water you use has been boiled for at least three minutes, and then allowed to cool. Boiling kills the protozoa.

According to the Centers for Disease Control and Prevention, the only certain way to prevent an infection when swimming is to avoid water-related activities in warm freshwater. If you choose to swim, limit the amount of water going up the nose, and avoid water where Naegleria fowleri might live. This is any water that is warm and fresh. The protozoa are not found in ocean water.

Here are some tips on avoiding Naegleria fowleri infection:

- Hold your nose shut, use nose clips, or keep your head above water when taking part in water-related activities in bodies of warm freshwater.  This includes activities in warm water discharged from industrial plants.

- Avoid putting your head under water in hot springs and other untreated geothermal waters.

- Avoid water-related activities in warm freshwater during periods of high water temperatures and low water levels.

- Avoid digging in, or stirring up, the sediment while taking part in water-related activities in shallow, warm freshwater areas.

It seems that every time we turn around, there is something else to worry about. There are some truly spooky dangers in the world, and the Naegleria fowleri amoeba is one of them. Invisible to the naked eye, found all over the world, and almost always fatal, this parasite is one to avoid.