Evidence has grown that climate change already contributes to the global burden of disease and premature deaths. Climate change plays an important role in the spatial and temporal distribution of malaria, dengue, tick-borne diseases, cholera, and other diarrhoeal diseases; is affecting the seasonal distribution and concentrations of some allergenic pollen species, and has increased heat-related mortality.
Long before the role of infectious agents was discovered, late in the nineteenth century, humans have known that climatic conditions influence the appearance and spread of epidemic diseases. Several kinds of health impacts from higher temperatures have been identified, both direct and indirect. The long term will see the predominance of indirect effects, including the spread of vector-borne infectious diseases, such as malaria, dengue, yellow fever, plague, trypanosomiasis, and leishmaniasis, which have been major causes of morbidity and mortality throughout human history, accounting for more human disease and death in the 17th through early 20th centuries than all other causes combined
The potential adverse effects of global climate change and extreme weather events may be unequally distributed, and could be particularly severe in countries with already high disease burdens, like sub-Saharan Africa and Asia. The projected health impacts of climate change are predominately negative, with the most severe impacts in low-income countries where the capacity to adapt is weakest. Vulnerable groups in developed countries also will be affected.
On Tuesday, December 4, 2007 and Wednesday, December 5, 2007, the Institute of Medicine’s Forum on Microbial Threats hosted a public workshop entitled "Global Climate Change and Extreme Weather Events: Understanding the Potential Contributions to the Emergence, Reemergence and Spread of Infectious Disease."