The influence of weather on infectious diseases has been recognized for centuries. In our own experience, we know that some diseases like influenza are more common in the winter or others thrive better in the tropics. The effects of climate – weather over long periods of time – on infectious diseases have been getting a lot of attention lately. I was recently interviewed for a Focus Earth episode on infectious diseases and climate change. The introductory clip frames a debate between a calculated scientific position for the impact on individual infectious disease versus broad generalizations about global warming. It makes for great television and offers an opportunity to educate and engage the public about the health impact of climate change. In this case, both positions are true but highlight the difficulties in communicating the complexity of health effects from climate change – especially when we try to isolate the effects of climate from other biologic, ecologic, or social changes that lead to changes in infectious diseases.
There is no doubt that a dramatic increase in global temperature will cumulatively have a profound negative effect on health. This impact will be from a combination of factors including direct heat effects, increase in rainfall, extreme weather events including droughts and floods, and changes in air quality. There will also be changes in climate-sensitive infectious diseases such as zoonotic, vector-borne, environmental (fungi), and food/water borne diseases. These effects are most likely to be felt in tropical and semi-tropical countries which are least likely to be able to adapt to the changing climate. However, specific predictions about individual infectious diseases requires both 1) more information on the impact of climate and the geographical distribution of existing diseases, reservoirs, vectors, and pathogens which are all interconnected (for more information about infectious diseases at the interface of people, animals, and the environment, check out: www.cdc.gov/nczved/framework/); and 2) the ability of individual communities to adapt to these changes.
The need for better information to drive prediction and preparedness activities cannot wait. The effects of recent climate change are already evident in the northward presence of Vibrio vulnificus infecting oysters in Prince William Sound, the tropical Cryptococcus gattii fungal infections in the Pacific Northwest, expansion of tick-borne encephalitis in Sweden, and suggestions of shorter respiratory syncytial virus seasons in the United Kingdom. For more on CDC’s climate change activities visit Climate Change and Public Health. Please also share your thoughts.