Killer amoeba discovered in swimming spots south of Perth

Popular swimming spots south of Perth have been forced to shut over a recent growth of killer amoeba detected in the waters.

A scorching heatwave across south and central parts of the state this week has deteriorated water quality and created the perfect environment for the Naegleria amoeba.

Naegleria fowleri - the organism responsible for amoebic meningitis - can cause a fatal infection to the brain once inhaled, particularly in children.

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The Shire of Waroona this week conducted water testing and found the free-living amoeba in the Drakesbrook Weir Lake.

The spot has been closed while officials await results to rule out the presence of the Naegleria fowleri.

Shire president Mike Walmsley said the recent hot weather had led to the amoeba growth, but councils are prepared for it every summer with periodical water testing.

There is potential for more freshwater swimming spots to test positive for the fatal amoeba in the coming weeks, he added.

But, despite the closure, residents were still swimming in the possibly dangerous waters.

"It's really hard to stop them from doing it," Walmsley said.

"Just be mindful, especially with little ones, until we can actually cancel out that the (Naegleria fowleri) is present."

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Last week in the nearby Shire of Harvey, the deadly amoeba was detected in Brunswick Pool during a routine water testing and has been closed since.

While authorities said the risk of contracting amoebic meningitis is low, residents are urged to avoid the waters until it is deemed safe.

Signage has been erected in both locations to warn the community of the detections.

The Bureau of Meteorology has, however, forecast heatwave conditions to worsen across the state through to Saturday - increasing the risk of Naegleria fowleri growth.

Central western regions are under extreme heatwave warnings, while central parts are set to face severe temperatures and most remaining parts of the state to see low heatwave conditions.

What are the symptoms of amoebic meningitis?

According to the WA Department of Health, the following symptoms usually appear within five days of infection:

• Severe and persistent headache
• High fever
• Sore throat
• Nausea
• Vomiting
• Neck stiffness
• Confusion and hallucinations
• Drowsiness
• Coma

Anyone concerned about a potential amoebic meningitis case is urged to present to an emergency department or doctor immediately.