Brain-eating Amoeba Reported in Rare Medical Case in Florida

The Florida Department of Health (DOH) has confirmed one case of infection with the brain-eating amoeba Naegleria fowleri in the state.

The DOH identified the case in Hillsborough County in the west central portion of Florida. They did not reveal what condition the patient is in.

Infections with Naegleria fowleri—a single-celled organism commonly found in warm freshwater, such as lakes, rivers and ponds, as well as geothermal water, and soil—are very rare. There were only 34 cases reported between 2009 and 2018 in the United States, according to the U.S. for Disease Control and Prevention (CDC.)

Infection can cause a disease known as primary amebic meningoencephalitis (PAM)—which destroys brain tissue, causing brain swelling and, in most cases, death. The fatality rate of the disease is over 97 percent, with only four of the known cases in the U.S. having survived.

The initial symptoms of PAM appear anywhere between one and nine days after infection. These symptoms include stiff neck, confusion, lack of attention to the surrounding environment, loss of balance, seizures and hallucinations.

Once symptoms appear, the disease progresses rapidly, usually resulting in death anywhere between one and 12 days after onset, according to the CDC.

Infections can only occur when water contaminated with the amoeba enters an individual's nose, which in the vast majority of cases happens when people are swimming or diving in bodies of warm freshwater, such as lakes and rivers.

In very rare cases, people have been infected via other sources, such as when inadequately chlorinated swimming pool water or contaminated tap water entered the nose. For example, of the 34 cases recorded between 2009 and 2018 in the U.S., three people were infected after performing nasal irrigation using contaminated tap water, while one person was infected via contaminated tap water used on a backyard slip-n-slide.

It is not possible for infections to occur by drinking contaminated tap water, and the amoeba is not known to be transmissible via water vapor or droplets in the air, such as shower mist, according to the CDC. Furthermore, the infection cannot spread from person to person.

The amoeba is found across the globe, but in the United States most infections occur in the southernmost states. While very rare, infections are most common during the summer months, usually occurring during periods of persistent heat, when water levels drop and water temperatures rise. The ideal water temperature for the amoeba is around 115 degrees Fahrenheit.

Naegleria fowleri
This image depicts the effects on tissue from amebic meningoencephalitis caused by Naegleria fowleri parasites. Smith Collection/Gado/Getty Images

While Naegleria fowleri has only caused 37 known infections since 1962 in Florida, the state DOH is reminding people about precautions they can take following the latest case, even though the risk of infection is very small.

"Adverse health effects on humans can be prevented by avoiding nasal contact with the waters, since the amoeba enters through the nasal passages," a DOH statement said.

Health officials recommend avoiding water-related actives in warm freshwater and hot springs, particularly during periods of high water temperatures and low water levels.

If people do decide to take part in water-related activities in warm freshwater, experts recommend holding the nose shut or using nose clips. They should also avoid digging to stir up the sediment in shallow, warm freshwater areas. People should also only use boiled and cooled, distilled, or sterile water when rinsing their sinuses.