It sounds like science fiction, but it's true: A killer amoeba living in lakes enters the body through the nose and attacks the brain, where...

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PHOENIX — It sounds like science fiction, but it’s true: A killer amoeba living in lakes enters the body through the nose and attacks the brain, where it feeds until you die.

Even though encounters with the microscopic bug are rare, six boys or young men have been killed this year. The spike concerns health officials, and they are predicting more cases.

“This is definitely something we need to track,” said Michael Beach, a specialist in recreational-waterborne illnesses for the Centers for Disease Control and Prevention (CDC).

“This is a heat-loving amoeba,” Beach said. “As water temperatures go up, it does better. In future decades, as temperatures rise, we’d expect to see more cases.”

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According to the CDC, the amoeba, Naegleria fowleri (nuh-GLEER-ee-uh FOWL-erh-eye), killed 23 people in the United States from 1995 to 2004. Health officials this year have recorded six cases: three in Florida, two in Texas and one in Arizona. Only several hundred cases worldwide are known to have occurred since the amoeba’s discovery in Australia in the 1960s.

In Arizona, David Evans said nobody knew his son, Aaron, 14, was infected until after he died Sept. 17. The teen seemed to have nothing more than a headache.

“We didn’t know,” Evans said. “And here I am: I come home and I’m burying him.”

After more tests, doctors said the teen probably picked up the amoeba a week earlier while swimming in the balmy shallows of Lake Havasu, a popular man-made lake on the Colorado River straddling the Arizona-California border.

Although infections tend to be found in Southern states, the amoeba lives almost everywhere in lakes, hot springs, even dirty swimming pools, grazing off algae and bacteria in the sediment.

Beach said people become infected when they wade through shallow water and stir up the bottom. If someone allows water to shoot up the nose — say, by doing a somersault in chest-deep water — the amoeba can latch onto the olfactory nerve.

The amoeba destroys tissue as it heads to the brain, where it continues the damage, “basically feeding on the brain cells,” Beach said.

Infected people tend to complain of a stiff neck, headaches and fevers. In later stages, they will show signs of brain damage such as hallucinations and behavioral changes, he said.

Once infected, most people have little chance of survival. Some drugs have stopped the amoeba in lab experiments, but people who have been infected rarely survive, Beach said.

“Usually, from initial exposure, it’s fatal within two weeks,” he said.

Researchers have much to learn about Naegleria. They don’t know why, for example, children are more likely to be infected, and boys are more often victims than girls.

“Boys tend to have more boisterous activities [in water], but we’re not clear,” Beach said.

In Central Florida, authorities started an amoeba hotline advising people to avoid warm, standing water and areas with algae blooms. Texas health officials also issued warnings.

People “seem to think that everything can be made safe, including any river, any creek, but that’s just not the case,” said Doug McBride, a spokesman for the Texas Department of State Health Services.

Officials in Lake Havasu City, Ariz., are discussing whether to take action. “Some folks think we should be putting up signs. Some people think we should close the lake,” city spokesman Charlie Cassens said.

Beach cautioned that people shouldn’t panic about the brain-eating bug. Cases are extremely rare, considering the number of people swimming in lakes. The easiest way to prevent infection, Beach said, is to use nose clips when swimming or diving in fresh water.

“You’d have to have water going way up in your nose to begin with” to be infected, he said.

David Evans has tried to learn as much as possible about the amoeba, but it doesn’t make much sense to him. His family had gone to Lake Havasu countless times. Have people always been in danger? Did city officials know about the amoeba? Can they do anything to kill it?

Evans’ family lives within eyesight of the lake. With temperatures in the triple digits all summer, the Evanses and almost everyone else in the region look to the lake to cool off.

It was on David Evans’ birthday, Sept. 8, that he brought Aaron, his other two children and his parents to Lake Havasu. They ate sandwiches and spent a few hours splashing around.

“For a week, everything was fine,” Evans said.

Aaron then got the headache. Doctors first suspected meningitis. Aaron was rushed to another hospital in Las Vegas.

“He asked me at one time, ‘Can I die from this?’ ” David Evans said. “We said, ‘No, no.’ “

Aaron stopped breathing Sept. 17 as his father held him in his arms.

“He was brain-dead,” Evans said. Only later did doctors and the CDC determine that the teen had been infected with Naegleria.

“My kids won’t ever swim on Lake Havasu again,” he said.

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