In Australia there are two groups of free-living amoebae that have been associated with opportunistic infections in humans, Naegleria and Acanthamoeba. ALS Water Melbourne and Perth laboratories now offer NATA accredited analysis of amoebae in waters including PCR confirmation (Melbourne).
Naegleria fowleri is the most notorious free-living amoeba owing to its etiology with the rare but fatal disease PAM (primary amoebic meningoencephalitis). Infection occurs via intranasal pathways rather than ingestion therefore the greatest risk of infection is through recreational bathing. Chlorine is effective in treating contaminated water supplies although chloramination is required to ensure adequate disinfection of entire water distribution systems. N. fowleri is a thermophilic amoeba and has been detected in every Australian state and territory. Growth is fastest above 42ºC, but it also occurs at temperatures as low as 25ºC. Below 18ºC it is thought to occur as a dormant cyst. Although there are a number of species of Naegleria in Australian waters not associated with disease, the presence of any thermophilic amoeba is usually of concern.