Climate Change and Infectious Disease: How a Warming World Shapes Public Health
Climate change is often discussed as an environmental issue, however, its effects on human health are becoming increasingly evident. While some might picture melting ice caps when thinking of global warming, the process has also already begun to reshape disease patterns. The increased spread of mosquito-borne diseases and the impact of heat on water safety are prominent examples that have emerged as major public health concerns in recent years. The World Health Organization (WHO) estimates that climate change will contribute to an additional 250,000 deaths per year between 2030 and 2050 due to malaria, malnutrition, diarrhea, and heat stress, highlighting the tangible human cost of a warming planet.1 Climate change expands infectious disease risks through environmental, ecological, and social pathways, posing significant challenges for public health systems.
One consequence of increasing global temperatures is the lengthening and shifting of seasons. For example, mosquitoes, which carry malaria, and ticks, which carry Lyme disease, now have longer transmission periods. The changing climate also allows these vectors to expand into regions where they were not previously found. For example, Valley fever, caused by the fungus Coccidioides, which prefers hot, dry soil, is emerging in new areas of the United States as climate change raises temperatures and alters rainfall patterns.2 As a result, climate change can alter both where and when diseases occur. These shifts have important public health implications because hospitals must be prepared for increased cases, and health officials may need to educate the public about the potential risks of exposure, such as encouraging vaccination campaigns, vector control measures, and safe water practices.
The changing climate also increases the risk of water- and food-borne diseases. Global warming may be accelerating the water cycle and redistributing rainfall, leading some regions to experience heavier rainfall and others to face more extreme droughts.3 These shifts in weather can pose serious health risks. For example, increased flooding or heavy rainfall can contaminate water supplies or damage sanitation facilities, while drought can lead to poor hygiene conditions. Additionally, warmer water temperatures promote faster bacterial growth, contributing to more frequent outbreaks of diseases such as cholera and salmonella.
Climate change has indirect but significant health impacts, weakening healthcare systems and increasing population vulnerability. As environmental conditions worsen, communities may be displaced and forced to migrate, often into areas with limited resources or inadequate healthcare infrastructure. Simultaneously, the increased burden of infectious diseases can strain healthcare systems, making it more difficult to respond effectively to outbreaks. Additionally, climate change can disrupt farming and food distribution, as shifting rainfall patterns and extreme weather events reduce crop yields, leading to food insecurity and malnutrition in vulnerable populations.3 These conditions can further weaken immune systems and increase susceptibility to infection, compounding the overall public health impact. Vulnerable populations, including the elderly, children, and those in low-income regions, are particularly at risk, as limited access to healthcare and clean water amplifies these impacts. Urban areas may face higher disease transmission due to population density, while rural regions may struggle with agricultural losses and food insecurity.
Despite these challenges, effective public health responses can mitigate their impact. A changing climate underscores the need for more proactive and coordinated systems. Climate-informed health planning will be essential in developing a structured approach to this issue. Greater health surveillance to identify outbreaks early will also play a key role in mitigating future risks to populations. Global cooperation is equally important, as one country’s pollution can affect another, and infectious diseases are not confined by borders. Strong communication and coordinated responses between nations will be critical in effectively addressing these growing public health challenges.
References
- World Health Organization. Climate change and health. Geneva: WHO; 2021. Available from: https://www.who.int/news-room/fact-sheets/detail/climate-change-and-health
- Centers for Disease Control and Prevention. Climate and infectious diseases. Atlanta (GA): CDC; 2024. Available from: https://www.cdc.gov/ncezid/topics-programs/climate-infectious-disease.html
- Met Éireann. The water cycle. Dublin: Met Éireann; [cited 2026 Mar 23]. Available from: https://www.met.ie/education/outreach-water-cycle/
