Pool scare a case of mistaken amoebae

Last week, mainstream media in Western Australia went into overdrive reporting that a swimming pool in the Perth suburb of East Victoria Park had detected acanthamoebae.

The media reports further stated that this amoeba is a rare parasite that can cause blindness and serious brain infection, quoting the website of highly influential US organisation, the Centres of Disease Control.

Unfortunately (or more correctly, fortunately, as it turns out) these reports were inaccurate in two ways. WA Health confirmed the amoebae found in the Aqualife pool centre were thermophilic amoebae, not acanthamoebae.

And second, even if the amoeba had been acanthamoebae, the Australian variety is much different to the amoeba found in the US. In Australia, there are no documented instances of amoebic keratitis, the disease caused by acanthamoebae embedding itself in the abraded surface of the cornea of a contact lens wearer.

The US variety is also more likely to be found in open bodies of water than swimming pools.

Thermophilic amoebae is much less of a concern and can come from human saliva. It may be found in the cracks in tiles or in other biofilm in the swimming pool. WA Health has recently changed its approach to dealing it. In the past, they used to prescribe closing the pool and superchlorinating. Now they just note its presence and superchlorinate.

WA Health samples 2000 pools per month in 1200 locations. Their Code of Practice states the action to be taken for both forms of amoeba (see page 39).

The presence of an acanthamoebae may also disguise the presence of a Naegleria organism, and should be regarded as a higher risk than thermophilic amoebae detected in isolation.

Management at Aqualife posted a statement saying the facility adheres to the Department of Health’s guidelines for water testing and treatment at all times. An anomaly was detected on Wednesday 18 February in the 25m pool, therefore the pool was closed at 11am. The facility's response was immediate and thorough. Procedures were followed resulting in the Health Department approving the pool to be reopened at 5:30am, Friday 20 February.

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