What is the link between climate change and infectious disease?

Climate change is widespread, rapid and intensifying.  

Homes are being lost due to unprecedented floods and fires, heat-related illnesses are on the rise, and our food systems are increasingly at risk.  

While rising global temperatures are proving disastrous for humans, they’re providing the perfect environment for many climate-sensitive infectious diseases to thrive. 

Global warming is expanding the areas in which disease-carrying vectors (like mosquitoes and ticks) can survive. Higher levels of rainfall, flooding and droughts can create stagnant water for vectors to breed or increase the risk of contaminated water. And extreme weather events can disrupt existing infrastructure, sanitation and health systems, making many more vulnerable to infection.

Other factors linked to climate change can also play a role in the spread of infectious diseases: like migration, urbanisation and deforestation. However, due to the complex, overlapping factors at play, it can be challenging to link these impacts directly to climate change.

The March 2022 report from the Intergovernmental Panel on Climate Change (IPCC) warned that without swift climate action we will see an escalation of infectious diseases. They will spread to new regions (and may decline in some endemic areas). They’ll surge in areas where they were previously under control. And diseases that have never previously infected humans (Disease X) may 'spill over' from animals.

Discover more about how climate change is affecting:

While climate change may increase diseases in nature, whether this leads to an increase in disease risk for humans depends upon a range of societal, infrastructure and medical factors.

Mitigation 

The most important thing we can do is act now to limit the impacts of climate change. This means reducing the flow of heat-trapping greenhouse gases into the atmosphere. We can do this in two ways: 

1. reduce the sources of these gases (for example, the burning of fossil fuels for electricity, heat or transport) 
2. preserve and restore the 'sinks' that accumulate and store these gases (such as the oceans, forests, peat and soil) 

As the IPCC noted, we must stabilise greenhouse gas levels "in a timeframe sufficient to allow ecosystems to adapt naturally to climate change, ensure that food production is not threatened and to enable economic development to proceed in a sustainable manner”. 

Adaptation 

While mitigation provides global benefits, adaptation often happens on a regional or local level. We need to explore and implement ways to adapt to life in a changing climate.  

• Strengthen our health systems to reduce the burden of disease. This can include setting up surveillance systems that will pick up early evidence of emerging infections or changes in occurrence as a result of climate change. 
• Support new research. The intersections of infectious disease and climate science are rarely explored. We must bring these two communities together to catalyse new research and strengthen our capacity to respond to emerging threats. 
• Invest in a collaborative approach. To effectively detect, respond to, and prevent outbreaks of disease and food safety problems, epidemiological data and laboratory information should be shared across sectors. Governments, researchers and workers across sectors at the local, national, regional and global levels should implement joint responses to health threats. 
• Sustainable urban development. The World Bank predicts that more than one billion people are at risk of being driven from their homes for climate-related reasons. As more people move into cities as a result, we must ensure that we build cleaner and greener while ensuring that everyone has access to clean water and sanitation.

This article was first published on 12 May 2022.