Understanding the risk of acute gastrointestinal disease from contaminated drinking water

Scientists are using latest metagenomic technology to identify the presence of acute gastrointestinal disease-causing microbes in drinking water as part of a Te Niwha-funded project to understand the real risk of contaminated water to human health.

Te Niwha is the national infectious diseases research platform and involves scientists from universities, crown and private research institutes in partnership with communities across the motu to be best protect Aotearoa New Zealand from current and emerging infectious diseases.

The ‘Burden of waterborne diseases’ project is led by the Te Whare Wānanga o Waitaha | University of Canterbury’s Associate Professor Tim Chambers and Connor Redmile of Te Kura Taka Pini Limited, the Ngāi Tahu freshwater group.

Dr Chambers says an estimated 18,000 to 34,000 people in Aotearoa develop acute gastrointestinal disease (AGI) each year from contaminated drinking water supplies. However, this estimate was completed almost 20 years ago.

Dr Chambers says results from the Te Niwha-funded project will clarify the public health burden of contaminated drinking water, identify parts of the country’s water infrastructure most likely contributing to this burden, and areas and communities most affected. It will also provide national and local water authorities direction on ways to minimise the impact of water-borne diseases from drinking water.

“Information from the project will provide insights into both the risk and best interventions to ensure all New Zealanders have access to clean drinking water.”

Dr Chambers says smaller supplies are often at greater risk of contamination and associated waterborne disease. This includes people on domestic self-supplied water that is not covered by drinking water regulation.

“An important part of the project has been to trial a testing and training programme that supports community water providers. We are doing the trial with marae throughout the South Island.”

Connor Redmile developed and carried out the training and testing programme with key people from 19 marae in the takiwā.

Redmile says the programme provides training on key issues around drinking water safety, how to collect water samples, analyse results and assess appropriate treatment options.

“Samples collected from marae Māngai Wai Māori Water Champions are sent to the Institute of Environmental Science and Research (ESR) and tested for the indicator bacteria E. coli. We are also trialling the use of state-of-the art metagenomics testing. This new tool allows us to look at all microorganisms present rather than just one indicator bacteria. Tracking differences in the microbial communities present in the water can provide better information on potential risks present in both the source and treated water. This surveillance tool can also be used to evaluate the effectiveness of local water treatment systems on the microbiological communities present.”

Redmile says the project has created a network of water champions who can share the knowledge with their community and ensure safe drinking water as well as complying with legislation.

Te Niwha Mana Whakahaere Te Pora Thompson says the waterborne diseases project is one of a number funded by Te Niwha that provide robust evidence and solutions for infectious diseases present in or able to be detected in water.

ESR are leading two studies involving water and infectious diseases:

• One trialling the use of wastewater from aircraft and communal buildings to better detect the presence of infectious diseases. Wastewater sampling was used during the COVID-19 pandemic to identify the presence of the virus in areas.

• A second ESR-led project looks at how best to conduct surveillance and reporting for emerging disease threats carried by water, using the bacteria Vibrio as a case study. Vibrio infections present as gastroenteritis or tissue infections that can be mild or very serious. The bacteria live in aquatic environments and people become infected from eating contaminated kaimoana (seafood) or coming into contact with contaminated water.

Te Niwha Kia Niwha Fellow Dr Rose Collis of AgResearch leads a project using environmental DNA (eDNA) to determine if freshwater samples and spiderwebs can be used to monitor the presence of antimicrobial resistance (AMR) in the environment.