Climate change could undermine progress in reducing waterborne diseases, study finds

More frequent extreme weather events, driven by climate change, could undermine decades of the world's progress in reducing waterborne diseases, a review has found.

Waterborne diseases are a major cause of mortality and morbidity, especially in low and middle-income countries and among children aged under five.

Climate change does not affect all disease-causing microorganisms -- or pathogens -- the same way; it is altering the environmental conditions that determine whether pathogens survive, spread and infect new hosts, showed findings published in the journal Nature Reviews Microbiology.

Researchers -- led by those at the University of Colorado Anschutz and the University of Washington in the US -- said that climate change is thus modifying the spread of waterborne diseases around the world.

Therefore, public health response should be tailored to specific pathogens, as bacteria, viruses and parasites each respond differently to changing environmental conditions, they said.

"We want people to know climate change alters the conditions that allow pathogens to spread," co-author Elizabeth Carlton, professor and chair of the department of environmental and occupational health at the University of Colorado's school of public health, said.

"It's (climate change) making it harder to control some of the world's most deadly infectious diseases by creating more favourable conditions for transmission," Carlton said.

For example, the review found that while waterborne diseases are often associated with flooding and heavy rainfall carrying pathogens into drinking water supplies, droughts can also increase disease risk by reducing one's access to safe water and changing how people use the water that is available.

Higher temperatures can enable bacterial and protozoan waterborne pathogens to survive, reproduce and be more virulent, while a drought can concentrate the microbes on the surface and contaminate water that is available, it said.

The researchers also explained that rising temperatures generally promote bacterial growth, while viruses, including norovirus, rotavirus and adenovirus, spread more easily under cooler, drier conditions, and may decrease in a warmer world.

"Climate change threatens to undermine the progress that has been made in reducing waterborne diseases," the authors wrote.

Waterborne diseases spread at the intersection of three components -- agent, host and the environment -- of the classic epidemiological triad for infectious diseases, they said.

"Climate change has an impact on the fate and transport of waterborne pathogens and ultimately the risk of waterborne diseases by affecting each component of the triad: climate change can alter the survival, reproduction, virulence and die-off rates of pathogens; it can alter the distribution, behaviour, and susceptibility of human hosts; and it can affect water and sanitation infrastructure and the mobilisation of pathogens across environments," the team wrote.

Outlining practical strategies to help communities adapt, the researchers called for an increased investment in climate-resilient water, sanitation and hygiene infrastructure.

They also recommended expanding pathogen-specific disease surveillance, tailored to specific pathogens, and strengthening vaccination programmes.

"Climate change is changing the rules of how these diseases spread. The good news is we already have many of the tools needed to reduce risk. The challenge now is making sure they are designed and deployed for the climate conditions we are facing today and the ones we will face in the future," Carlton said.

Published on July 17, 2026