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How Climate Change is Fueling a Rise in Deadly Diseases

Nation of Change, 7/18/13

By Sy Mukherjee

In the summer of 2012, the mosquito-borne West Nile virus made a surprising comeback in America. In Dallas, the most affected region, 400 people contracted the disease and 19 of them died. That came as a shock to public health officials, since West Nile virus was thought to be in such precipitous decline that it was practically eradicated.

Now, a little detective work has led epidemiologists to the reason for its resurgence: warmer winters and wetter springs. In other words, the consequences of global climate change are fueling West Nile. And it’s just the tip of the iceberg. Health officials expect the number of people contracting other infectious diseases to rise right alongside global temperatures.

The diseases that are propagated by climate change tend to come in fungal, algal, tick-borne, and mosquito-borne forms. For instance, dengue fever — which causes a high fever, painful head and body aches, and rashes — will likely continue infecting Americans in hot and humid climates, as well as regions that are close to warming oceans:

map chart

That’s because warmer waters allow mosquitoes, which are the primary vessels for dengue fever transmission, to breed and live more freely. According to the World Health Organization (WHO), “Mosquito species such as the Anopheles gambiae complex, A. funestus, A. darlingi, Culex quinquefasciatus and Aedes aegypti are responsible for transmission of most vector-borne diseases, and are sensitive to temperature changes as immature stages in the aquatic environment and as adults.”

Mother Jones notes that warming oceans also affect aquatic wildlife like reef fish. Dangerous algal blooms, which are caused by warmer waters and dying coral reefs, can infect fish that eventually makes its way into the human food chain. In 2007, nine North Carolina residents contracted ciguatera, or fish poisoning, from infected fish that had been caught off the coast of Florida.

But it’s not just coastal and humid regions that are feeling the effects of diseases that are propped up by climate change. In the western United States, states like New Mexico, Arizona, and California are experiencing an inexplicable rise in Valley fever, which causes head and neck aches, serious respiratory problems, has no cure or vaccine, and can be lethal. The condition is caused by fungus that resides in spores in the soil that are lifted off of the ground due to dry weather that is a consequence of global warming-related drought.


Furthermore, illnesses that currently impact other countries could flourish in the United States if they were to find their way here. Rift Valley fever — which causes fever, vertigo, and neck stiffness — is also spread through mosquitoes.

Public health officials in Europe and the U.S. Centers for Disease Control (CDC) have publicly warned that populations should prepare for a rise in these diseases as a consequence of global climate change. But currently, only eight states have taken measures to prepare to combat the public health consequences of climate change.



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