Study looks at microscopic killer parasite

By Takuma Konno, Year 12, Trinity Anglican School

WHEN I read about the deaths of three children from Primary Amoebic Meningoencephalitis (PAM) that occurred in the Winton-Richmond area — halfway between Townsville and Mount Isa — in 2015, I was alarmed.

No one suspected, least alone the parents, that children could die from playing with a hose that carried water from a farm pond. This is why I embarked on my extended experimental investigation (EEI) study of PAM in the Cairns area.

My ultimate goal is to bring this little known hazard to the attention of people in the Cairns area, so that we are all better informed.

PAM is a rapidly fatal neurological disease caused principally by Naegleria fowleri, a freshwater amoeba that is parasitic to certain mammals, including humans.

This disease is exceedingly rare with only 310 known cases recorded as of 2012; however, because of its 95 per cent fatality rate, it is a potentially serious health hazard in freshwater swimming areas.

The amoeba can be found in non-chlorinated, freshwater bodies in warm climates.

Some may feel it is alarmist to worry the public over a disease that is exceedingly rare.

Given the mortality rate of the disease, it is my opinion that we cannot risk even a single case in any region endemic for the amoeba.

I have lived in the Cairns area for five years and I have never heard of a study being conducted for this parasite; nor have I seen a signposted warning people of the presence of this organism.

To identify whether there were any incidence of N. fowleri in freshwater sites in the Cairns area, I sampled a number of sites and conducted a qualitative and quantitative analysis of the water and sediment.

The Cairns waterways included are: Ryan Weare Creek, Crystal Cascades, Esplanade Lagoon, Goomboora Park and a stagnant freshwater site at Smithfield.

The method of testing had an extensive number of steps, which were conducted in the lab at Trinity Anglican School.

The amoeba, N. fowleri, can be cultivated on non-nutrient agar (NNA) which prevents general bacterial growth but promotes the growth of the amoeba.

I also added liquid E. coli as a food source for any amoeba present.

If the amoeba was present in the sample, we would see feeding tracks.

After incubating at 38-42C for 10 days, the NNA plates were assessed for amoebic feeding tracks, using a microscope.

I was excited to see numerous feeding tracks in the sample taken from the stagnant freshwater site at Smithfield, although we are unable to conclude that these amoebas are N. fowleri.

After conducting dilution calculations, there was a concentration of approximately 1333 amoebas per litre of water sample.

It is possible that these organisms are N. fowleri due to the site having the perfect conditions for growth.

However, further testing using Leifson’s Stain and DNA analysis should be conducted to confirm the presence of N. fowleri.

If this waterway does test positive, then a warning sign should be posted to inform the public of the findings.

The great news, though, is that all other samples were negative for any amoebas, which is a positive outcome.