Killer amoeba: Sounds like sci-fi, but it's real

A freshwater organism feeds on the brain if it finds its way up the nose of a hapless human.

By JACOB H. FRIES
Published October 8, 2007

	Will Sellars, 11, was infected with the deadly amoeba while wakeboarding at Lake Jessamine in Orlando on July 28. He died 10 days later.
[Family photo]

Don't panic. You have a better chance of dying from falling out of bed than from the brain-eating water bug in your local pond.

But as incredibly rare as it is, the microscopic amoeba has killed six people this year, including three boys in the Orlando area. The organism lives in freshwater and, if sucked deep into the nose, it feeds on the brain. Once infected, most people die within two weeks.

Will Sellars, 11, made it only 10 days.

He had gone wakeboarding on Lake Jessamine in Orlando on July 28. A few days later, he developed a rash. Then came headaches, vomiting and a trip to the hospital, where doctors struggled to diagnose the problem.

"It was like a science fiction nightmare," Will's uncle, Mark Zeitler, said recently. "Fortunately, I don't think Will recognized what was going on."

Health officials aren't sure what prompted this year's spike in deaths or why three occurred in a cluster in Central Florida. From 1995 to 2004, the amoeba called Naegleria fowleri killed 23 people in the United States, according to the Centers for Disease Control and Prevention.

Since the amoeba was first identified in the 1960s, only a few hundred cases have been reported worldwide.

Health officials end up walking a fine line between educating the public about the deadly amoeba and stressing the unlikelihood of an infection. After Sellars died, the Orange County Health Department, using the school district's automated phone system, notified the parents of 175,000 students.

"It's a very rare disease, so we're not trying to alarm people," department director Dr. Kevin Sherin said. "But it's something every parent should know about. ... If it happens to your child, it's no longer rare."

In the Tampa Bay area, county officials are well aware of the killer amoeba, but they say the risk is even smaller here because most people swim in the gulf and bay rather than freshwater lakes and rivers.

Naegleria occurs naturally in freshwater, including hot springs and poorly maintained swimming pools, and grazes off microbes in the sediment. It becomes active in hot temperatures and, as a result, appears more frequently in Southern states. The other three people killed this year were in Texas and Arizona.

"It's a heat-loving organism," said Dr. Michael Beach, a specialist in recreational waterborne illness for the CDC. "During heat waves, you tend to see spikes in cases."

Scientists still have a lot of questions about Naegleria, and because so few people get infected, they don't have many opportunities to study it. They don't know why children, especially boys, are more likely to be inflected. They can't tell whether it has to do with their growing bodies or their behavior in the water.

Doctors also don't know whether any medication can effectively stop the amoeba once it is inside the body, Beach said.

People tend to become infected in warm, shallow water after the bottom has been stirred up, distributing the amoebas, he said. They jump, dive or fall in the water, some of which shoots up their nose. The amoeba then latches onto the olfactory nerve and crawls into the brain.

"It's a random accident," Beach said. "I think that's what makes it so scary."

The first symptoms - headache, fever, stiff neck - don't typically sound many alarms and the infection progresses quickly. Many experience hallucinations by the time they are taken to a hospital. Doctors then try their best with medications.

"It's not clear that they work," Beach said. "But we keep using them because we know what the outcome will be if we don't."

Will Sellars, who was about to start the fifth grade, didn't show any symptoms for a couple of days. A sports fanatic, Will even felt well enough to play football with his 21-year-old brother the day after visiting the lake.

But before long, he was lethargic and confused. At the hospital, doctors initially told family they believed he had meningitis or encephalitis.

"They were very aggressive with the treatment, but unfortunately there's no cure," Zeitler said.

Nor is there any test to show definitively whether a body of water is amoeba-free, Beach said. One sample of lake water might not contain Naegleria, but the next sample, taken from a few feet away, could.

The easiest way to reduce the risk of infection is to use nose clips when swimming in freshwater and avoid the water during the hottest days of the year, health officials say. But considering that millions of people visit the country's lakes and rivers every year, chances of infection remain slim.

"We have to keep this in perspective," Beach said.

Staff researcher Caryn Baird contributed to this report. Jacob H. Fries can be reached at jfries@sptimes.com or 727 893-8872.

Reduce your risk

Infection from the deadly Naegleria fowleri amoeba is extraordinarily rare, but health officials offer a few tips to further reduce your risk:

Avoid swimming or jumping into freshwater during periods of high temperature and low water volume.

Hold the nose shut or use nose clips when jumping or diving into bodies of warm freshwater such as lakes, rivers or hot springs.

Avoid digging in or stirring up the sediment while swimming in shallow, warm freshwater areas.

Do not swim in areas posted as "no swimming" or in areas warning about an increased risk of Naegleria infection.

Source: CDC

[Last modified October 8, 2007, 14:00:16]