Health impacts of climate change: waterborne diseases

A summary of some of the main mechanisms by which climate change increases the risks of food and water-borne disease. Image: Global Climate & Health Alliance

Waterborne diseases are caused by a variety of microorganisms, biotoxins, and toxic contaminants, which lead to devastating illnesses such as cholera, schistosomiasis and other gastrointestinal problems.
Outbreaks of waterborne diseases often occur after a severe precipitation event (rainfall, snowfall).

Because climate change increases the severity and frequency of some major precipitation events, communities—especially in the developing world—could be faced with elevated disease burden from waterborne diseases. In addition, diseases caused by Vibrio bacteria such as cholera and other intestinal diseases may pose a greater threat due to the effect that rising sea temperatures will have on the growth and spread of bacteria.

Climate change is likely to increase diarrheal disease incidence worldwide, and extreme weather conditions may also complicate already-inadequate prevention efforts.

Health impacts of extreme weather

Droughts can cause increased concentrations of effluent pathogens, overwhelming water treatment plants and contaminating surface water. Older water treatment plants are particularly at risk.

Changes in ocean and coastal ecosystems, including changes in pH, nutrient and contaminant runoff, salinity, and water security, that can cause degradation of fresh water, particularly in areas where much of the population uses untreated surface water for daily consumption and activities.

Increased frequency of intense extreme weather events can cause flooding of water and sewage treatment facilities, increasing the risk of waterborne diseases.

Indirectly, the lack of water can cause pressure on agricultural productivity, crop failure, malnutrition, starvation, population displacement, and resource conflict.

Changes can occur in the distribution and concentrations of chemical contaminants in coastal and ocean waters through the release of contaminants previously locked in polar ice sheets, or in runoff from coastal and watershed development.

Mitigation and Adaptation

• Carbon sequestration,
• Water reuse and recycling
• Protecting wetlands to reduce damage to water quality from severe storms
• Increasing green space and decreasing paved surfaces in urban areas to reduce runoff, slow the rate of water table depletion, and reduce the impact of extreme precipitation events
• Increasing the use of air conditioning is associated with an increased demand in electricity, which can impact water availability and regional water ecology.
• Changing weather patterns and decreased food availability in the developing world can lead to increased desertification, and increase the need for above-ground irrigation. Such projects, if done in areas where waterborne parasitic diseases are present, can change the regional transport of the parasite and impact human exposure to disease.

Research needs

• Evaluating and monitoring exposures and health risks of chemical contaminants likely to be increasingly released and mobilized due to climate change
• Improving understanding of harmful algal blooms including their initiation, development, and termination, as well as the exact nature of the toxins associated with them
• Understanding how toxins, pathogens, and chemicals in land-based runoff and water overflow interact synergistically and with marine species, especially those important for human consumption, and the potential health risks of changing water quality

For more information, please visit the chapter on Waterborne Diseases in A Human Health Perspective on Climate Change.

• Adapted from source: National Institute Of Environmental Health Sciences

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