Climate change may aid spread of deadly diseases

Climate change may lead to deadly diseases spreading to new parts of the world, so says a new report by health experts from the Wildlife Conservation Society.

In the report, the experts write: ”The term 'climate change' conjures images of melting ice caps and rising sea levels that threaten coastal cities and nations, but just as important is how increasing temperatures and fluctuating precipitation levels will change the distribution of dangerous pathogens."

The authors have highlighted twelve diseases whose spread is likely to be facilitated by climate change. However, they stress that the list is not comprehensive, and that subsequent studies may eliminate diseases from the list of those aided by climatic factors. The list includes:

• Avian influenza: Current data suggests that the spread of the highly pathogenic strain of avian influenza HN51 is mostly due to the poultry trade. However, experts believe that the increased likelihood of drought and severe winter storms caused by climate change trade may increase contact between wild and domestic bird populations.
• Babesiosis: Babesia is a protozoal parasite transmitted to domestic animals and wildlife by ticks. Babesiosis is an emerging disease in humans, and is becoming increasing common in Europe and North America. 
• Cholera: Rising global temperatures are expected to increase the incidence of this water-borne bacterial disease.
• Ebola: Evidence suggests that outbreaks of Ebola hemorrhagic fever virus and the closely related Marburg fever virus are linked to unusual variations in rainfall/dry season patterns. Experts believe that the disruption and exaggeration of seasonal patterns that is caused by climate change will lead to an increasing number of outbreaks and will also lead to outbreaks of these diseases in new locations.
• Lyme disease: Lyme disease or borreliosis is the most common tick-borne disease in the northern hemisphere. It is expected to spread into new regions as tick distributions shift as a result of climate change. 
• Plague: Plague is still endemic in certain parts of the world. Rising temperatures and rainfall are expected to impact upon the distribution of rodent populations, which, in turn, will have an effect upon the incidence of rodent-borne diseases, such as plague. 
• Rift Valley Fever: Rift Valley fever virus (RVFV) is an emerging zoonotic disease, particularly in Africa and the Middle East. RVFV is spread to domestic animals by the bite of infected mosquitoes. The disease can be passed onto humans, and it can be fatal. There is a significant concern that climate change will facilitate the spread of RVFV.
• Yellow Fever: Yellow Fever is currently a problem in the tropical regions of Africa and parts of Central and South America. However, the disease, which is spread by the bite of infected mosquitoes, is expected to spread into new areas as changes in temperature and precipitation will enable infected mosquitoes to survive in previously unsurvivable habitats.

The Deadly Dozen: Wildlife Disease in the Age of Climate Change.  The Wildlife Conservation Society Website.  October 7th 2008.