CSIRO proposes a simple solution to fight a deadly water pathogen

Posted 21 April 2017

New research has found a new way to eliminate a deadly water pathogen from Australian waterways. 

A recent CSIRO study found that higher chlorination levels in drinking water help prevent Naegleria fowleri (N. fowleri) contamination and growth. 

N. fowleri is a waterborne amoeba that creeps along the central nervous system and feeds on brain tissue. Globally, the rate of primary amoebic meningoencephalitis (PAM), the disease caused by N. fowleri infection, is increasing. 

The good news is that you can’t contract it simply by drinking contaminated water. The amoeba only causes harm when contaminated water comes into contact with the olfactory nerves in the nasal cavity. But once contracted, the water pathogen is extremely deadly, with a 95% fatality rate. 

Historically, Australian water utilities have used between 0.2 and 0.5mg/L of free chlorine in drinking water distribution systems. 

This is enough to kill the vast majority of microorganisms. However, N. fowleri is often able to resist these chlorine levels, said Geoffrey Puzon from CSIRO’s Environmental Contaminant and Mitigation Technologies Program.

“An issue arises when pipeline sections do not receive a constant dose, as N. fowleri can survive intermittent doses of chlorine,” Puzon said. 

“In addition, the N. fowleri associated with the pipe wall biofilm is even more resistant due to the added protection from the biofilm.”

If it is able to interact with biofilm, the water pathogen can survive intermittent bursts of chlorine at concentrations of 20 mg/L. 

“Pipe wall biofilm develops in all water distribution systems, but can be significantly worse in pipelines exposed to warmer temperatures and low water flows, which both contribute to the loss of chlorine,” Puzon said.

Currently, Australian Drinking Water Guidelines require a boost of free chlorine levels to at least 0.5mg/L throughout a network if N. fowleri is detected. 

Puzon’s research shows that maintaining a level of more than 1mg/L in areas where the microbe occurs is enough to kill it, with the added bonus of changing the biofilm to prevent it from re-colonising.

“The research has provided water utilities with a target concentration of chlorine that has been demonstrated to remove N. fowleri from both the bulk water phase, but also the pipe wall associated biofilm,” Puzon said.

You can learn more about the effects of ​N. fowleri, cyanobacteria and other water-borne micro-organisms at the upcoming Ozwater'17 conference in Sydney, which has a public health stream. To learn more and to register, click here.