Brain-eating amoeba attacks junior Olympian track star Michael Riley

Michael Riley jnr: “The odds are not good”. Photo: Facebook Michael Riley jnr. Photo: Facebook

A star junior athlete is in a critical condition in the US after a killer parasite is believed to have swum up his nose while he was playing in a lake with his teammates.

Three times junior Olympian Michael Riley jnr, 14, was due to start high school on Monday but instead is fighting for his life at Texas Children’s Hospital in Houston with his family keeping vigil.

“Coming from a lake you wouldn’t think he’s going to the doctor’s office and they tell you he has a couple of days to live,” his father Mike Riley told KTRK-TV.

On August 19, a week after he jumped into a lake at the Sam Houston National Forest, he woke up with a headache and fever,  the family’s website said, but doctors at a local clinic could not identify the problem.

Two days later, he was disoriented with an unbearable headache and neck pain.

The rare naegleria fowleri amoeba is found naturally around the world in warm fresh water such as creeks, dams, rivers and hot springs but has also been identified in poorly maintained chlorinated swimming pools, industrial run-offs and water heaters.

Australia is considered a world leader in risk management for the brain-eating amoeba following multiple deaths in four states in the 1970s and 1980s.

Drinking the parasite does not cause infection, but, if it enters via water up the nose, it can travel to the brain and result in death within a day to two weeks.

Symptoms start one to nine days after infection including headache, fever, nausea and vomiting, progressing to a stiff neck, seizures, altered mental status and hallucinations.

The disease of the central nervous system it causes, called primary amoebic meningoencephalitis, is difficult to detect because it “progresses rapidly so that diagnosis is usually made after death” the US Centres for Disease Control and Prevention says.

“He is in critical condition and every hour is a waiting game to determine if he will pull through,” says the family’s “Miracle4Michael” Facebook page, which places faith in God and prayer while acknowledging that “the odds are not good” and inviting donations to help with medical expenses.

In the US only three people out of 133 infected in the past 50 years have survived.

The first PAM infections were identified in Australia in 1965 followed by multiple deaths over the next two decades.

The infections were linked to piping water long distances overland, which resulted in heated water with low disinfectant levels.

Water systems in Western Australia and South Australia continue to monitor for the parasite and there have been no infections in Australia since the 1980s, the US Centres for Disease Control and Prevention says.

Hope for the boy is thought to rest on a drug called miltefosine, which has been used to treat parasitic infections in other countries  but is regarded as experimental in the US.