Climate change and infectious diseases
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| Effects of climate change on human health |
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Climate change is influencing the transmission and burden of many infectious diseases worldwide. Rising temperatures, shifting rainfall patterns, and more frequent extreme weather events affect how pathogens, vectors and disease hosts interact. These changes are altering the geographic ranges and seasonal activity of disease-carrying organisms such as mosquitoes and ticks, and influence the growth and survival of bacteria and other pathogens in food and water systems.
Infectious diseases that are sensitive to climate can be grouped into: vector-borne diseases (transmitted via mosquitos, ticks etc.), waterborne diseases (transmitted through viruses or bacteria in water), and food-borne diseases (spread through pathogens in food). In 2022 scientists stated a clear observation that "the occurrence of climate-related food-borne and waterborne diseases has increased."
Vector-borne diseases like dengue fever, malaria, tick-borne diseases, leishmaniasis, zika fever, chikungunya and Ebola are especially sensitive to climatic conditions. Warmer and wetter conditions expand suitable habitats for vectors, enabling them to survive in areas that were previously too cold or dry. As temperatures rise at higher elevations and latitudes, transmission risks are expected to increase in parts of North America, Europe, and highland regions of Africa and Asia. For example, the range of ticks that transmit Lyme disease and tick-borne encephalitis has expanded, and further warming could lengthen their active seasons.
Climate change also affects waterborne and food-borne diseases by influencing water quality, sanitation, and microbial ecology. Warmer waters and increased flooding promote the growth and spread of bacteria such as Vibrio cholerae, which causes cholera, and other pathogens responsible for gastroenteritis and wound infections. Drought and poor access to clean water increase the risk of contamination and exposure to diarrheal diseases, typhoid, and hepatitis A.
The health impacts of these climate-related risks are unevenly distributed. Low-income countries and communities with high socio-economic constraints and limited healthcare, infrastructure and sanitation are the most vulnerable. Nearly one in three people globally lack access to safe drinking water, which amplifies exposure to waterborne pathogens and related illnesses. These conditions can also affect mental and social well-being and place additional strain on public health systems.
Without mitigation and adaptation measures, climate-related infectious disease risks will continue to rise. Limiting greenhouse gas emissions, strengthening disease surveillance, vector control, vaccination, water and sanitation services, and climate-resilient healthcare infrastructure is seen as essential to reducing these impacts.