Deadly amoeba thrives in Oklahoma heat, drought
BY TIM TALLEY Associated Press
Sunday, August 19, 2012
8/19/12 at 5:23 AM
OKLAHOMA CITY - High temperatures and an ongoing drought are having an impact on more than just crops and livestock.
State health officials say they are also creating ideal conditions for the growth of a tiny, single-cell organism that lives in Oklahoma's rivers, lakes and ponds and can cause a disease that is almost always fatal.
The organism, Naegleria fowleri, is being blamed for the death of a 9-year-old Bryan County boy who came down with a case of primary amoebic meningoencephalitis, or PAM, after swimming and diving in the Red River last month.
The amoeba that causes the disease occurs naturally in warm freshwater worldwide and in the U.S. is more prevalent in the southern states. This summer, triple-digit heat and lack of rain have caused temperatures to rise and water levels to fall in Oklahoma lakes and streams - a perfect environment for the organism to thrive, said epidemiologist Lawrence Burnsed of the Oklahoma State Department of Health.
"You have the conditions that are ripe for this amoeba to multiply," Burnsed said. "It is a severe disease. The vast majority of cases have resulted in death."
The fatality rate for people infected with the parasite is more than 99 percent, according to the Centers for Disease Control and Prevention. Of 123 people known to have been infected in the U.S. between 1962 and 2011, only one has survived, the CDC said.
Infections are rare. Between 2002 and 2011, only 32 infections were reported in the U.S., according to the CDC. Of those, 28 people were infected by contact with contaminated lakes, streams or other water used for recreation. Two people were infected by water from an untreated, geothermal drinking water supply, and two others were infected by contaminated tap water while irrigating their sinuses.
The latest Oklahoma victim was swimming with a group of people but was the only person infected, Burnsed said. Still, people need to be aware of the risk.
"It's not common, but there is a risk there," he said. "This is kind of a similar pattern of what's been observed before."
The organism infects people when water containing it gets in their nose and sinuses, typically when they swim or dive in contaminated lakes and rivers, according to information about PAM on the state Health Department's website. The amoeba then travels up the nose to the brain, where it causes inflammation of the lining of the brain and spinal cord, attacks the central nervous system and destroys brain tissue. The disease cannot be spread from person to person.
Symptoms include fever, headache, nausea, vomiting, stiff neck, seizures and eventually coma. In most cases, victims are described as young, healthy individuals who had been swimming three to seven days prior to the onset of symptoms.
Infections do not respond to routine treatment although Burnsed said a variety of antibiotics have been used. In the rare instances in which treatment has been effective it was started "very early" in the course of the illness, according to the state Health Department. Infected individuals generally die within a week.
Infections of the amoeba have been reported in other states this summer. The CDC says a 9-year-old boy died earlier this month after he became infected while swimming in a Minnesota lake. Another Minnesota child died from the disease two years earlier after swimming in the same lake. Officials have closed the lake to swimming as a precaution.
In South Carolina, an 8-year-old boy died last month about a week after he and other members of his family had gone tubing in a lake.
The boy from Bryan County is the latest victim from Oklahoma - but he is not the first. In August 2005, two Tulsa boys died after becoming infected with the organism while playing at the Mohawk Park splash pad. Afterward, officials closed the splash pad and announced plans to revamp it so it would not use recirculated water.
Original Print Headline: Disease-causing amoeba thrives in heat, drought
The Naegleria fowleri amoeba can thrive in warm freshwater lakes and rivers. If it enters the body through the nose, it can attack the brain and is almost always fatal. Tulsa World file