Water supplies at risk of Naegleria fowleri must ensure adequate primary disinfection (C.t >30 mg/L.min) and maintain a chlorine residual of at least 0.5 mg/L at all times, in all parts of their network to avoid potentially fatal amoebic meningitis.
Any water supply that seasonally exceeds 30°C or continually exceeds 25°C can support the growth of Naegleria.
Regularly monitor water temperature and chlorine residual throughout the entire distribution system.
Naegleria fowleri is an amoeba (microorganism), commonly found in warm freshwater and soil. It can cause a very rare but often fatal infection (amoebic meningitis or meningoencephalitis) if contaminated water goes up into the nose.
Any unchlorinated (or poorly chlorinated) water supply that seasonally exceeds 30°C or continually exceeds 25°C can support the growth of Naegleria. This includes reticulated raw water, reticulated drinking water, lakes, rivers, dams, bores, tanks, reservoirs, pipelines, natural hot waters/springs, and spa and swimming pools that are poorly maintained, under-chlorinated or unchlorinated. Low water usage, stagnation of water in pipes, biofilm and sediment build up, inadequate chlorination and warm air temperatures contribute to favourable conditions for growth of the organism. Naegleria cannot survive in water that is clean, cool and adequately chlorinated.
Contaminated water can enter the body through the nose, allowing the organism to then reach the brain. This may occur when people swim, dive or fall into warm water containing Naegleria, when children play under sprinklers or with hoses using this water, or when infected water is inhaled to cleanse the nasal passages. Children and young adults appear to be more susceptible to infections than adults. Infections usually occur when it is hot for prolonged periods of time, which result in higher water temperatures. You cannot get infected by swallowing water containing Naegleria.
Although Naegleria fowleri is commonly found in the environment, infection is rare. The organism was first identified in South Australia during the 1960s. A number of cases of infection occurred in towns there served by unchlorinated water delivered through long above-ground pipelines. Cases of amoebic meningitis have been recorded in South Australia, Western Australia, Queensland and New South Wales, and in many countries throughout the world. Recent cases in Australia have been associated with exposure to untreated private water supplies (bore water and a farm dam). Most Australian victims have been children.
NSW Health requests that water utilities include temperature as a field test when microbiology samples are collected as part of the NSW Health Drinking Water Monitoring Program. This will help to identify drinking water supplies that may be at risk from Naegleria fowleri.
Following tap disinfection and flushing, take a sample and then measure the temperature of the water coming from the tap. Do not use the sterile microbiology container to measure temperature. Please record the temperature in the ‘Comments’ field on the Allocated Microbiology labels (white) (and on the Additional (blue) or Repeat (pink) labels when used for microbiology).
Contact your local Public Health Unit on 1300 066 055 and refer to:
