Brain-Eating Amebas: Need to Know Info Before You Swim This Summer

Just this past June, only 11 days after visiting a water park in North Carolina, Ohio teen Lauren Seitz died from a brain infection caused by the ameba Naegleria fowleri. The microscopic, parasitic ameba is dangerous only if it enters a person’s nose, and authorities speculate that Lauren contracted primary amebic meningoencephalitis (PAM) after her whitewater raft turned over, submerging her in water.

This sad story immediately sent shock waves across America, for while PAM is quite rare—on average, less than four people catch the disease annually—the fatality rate is high. Of the 138 people known to have been infected in the U.S. between 1962 and 2015, only three have survived, according to the Centers for Disease Control and Prevention (CDC).  Still, says Dr. Amesh Adalja, a spokesperson for the Infectious Diseases Society of America, “rare and deadly infectious diseases get publicity out of proportion to the real risk.”

What you need to know: The ameba N. fowleri is extremely common in stagnant, warm water (especially at high temperatures up to 115 degrees). It can be found in lakes, ponds, rivers, hot springs and untreated swimming pools; this parasite doesn’t survive in salt water. It’s also worth noting that this ameba’s fresh water presence makes the Midwest, with all of its lovely lakes, a potential hot zone. That said, Dr. Adalja maintains that it’s currently not well understood why some individuals get infected with PAM in the same water while other nearby swimmers may not.

However, anything that causes an individual to breathe in contaminated water—such as diving, jumping into water or submerging your head—can let the one-celled parasite get into the nose, from which it may travel to the brain along the olfactory nerve. Much less commonly, the ameba can enter the nasal cavities when a person irrigates his or her nose with contaminated tap water via a neti pot. (The precaution here is to use sterile water.) In its natural state in ponds and lakes, Naegleria fowleri eats bacteria, but in the human body, the ameba uses brain tissue as a food source, causing swelling and other serious problems. Other nuggets: Individuals cannot get infected by drinking contaminated water, and the disease can’t spread from person to person. Recent statistics reveal that over 60 percent of U.S. cases occur in children ages 13 or younger.

All of this begs the question: Should warm freshwater swimming spots be tested for N. fowleri ? Experts say no. In a recent statement, the CDC relayed, “The CDC does not recommend testing rivers and lakes for Naegleria fowleri because the ameba is naturally occurring and there is no established relationship between detection or concentration of Naegleria fowleri and risk of infection.” Or, as Dr. Adalja puts it, “The ameba is there, we know that—you don’t need to test for it. But millions of people swim in contaminated ponds or lakes each year without getting infected.”

Once contracted, experts say PAM is hard to diagnose because it produces initial nonspecific, flu-like symptoms. “If you’ve gone swimming in fresh water and are experiencing severe headaches, neck stiffness and vomiting, it’s worth seeing a healthcare provider,” Dr. Adalja recommends.  

Wondering what else you can do to reduce your risk this summer? Protect yourself while swimming in a lake or pond by wearing a nose clip to prevent water from coming in, Dr. Adalja suggests. But you might focus your attention on other, more common summer risks. For instance, experts at the CDC point out that the odds of drowning are about 1,000 times that of getting PAM this season. So stay safe by being alert and focused while in the water this summer.

-- By Nancy Stedman