West Nile Virus and Other Diseases May Have an Unexpected Accomplice: Climate Change

Warmer winters make it easier for mosquitoes, ticks, mice and other disease carriers to spread health hazards.
Under drought conditions, creeks that would normally be flowing freely become a series of standing pools—and the ideal breeding ground for mosquitos. (Todd Korol/Reuters)
Aug 23, 2012
A former Gourmet staffer, Lawrence enjoys writing about design, food, travel, and lots of other stuff.

“The nation is heading toward the worst outbreak of West Nile disease in the 13 years that the virus has been on this continent,” The New York Times reported yesterday. “So far this year, there have been 1,118 cases and 41 deaths reported to the Centers for Disease Control and Prevention.” Dr. Lyle R. Petersen, director of the agency’s division of vector-borne diseases, added “That’s the highest number of cases ever reported to the C.D.C. by the third week of August.”

Scientific American has a theory as to why this might be the case:

“The fact that the worst U.S. West Nile epidemic in history happens to be occurring during what will likely prove to be the hottest summer on record doesn’t surprise epidemiologists. They have been predicting the effects of climate change on West Nile for over a decade. If they’re right, the U.S. is only headed for worse epidemics.”

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Science writer Christie Wilcox goes on to say, “Higher temperatures bolster the chances of infection on many fronts. Temperature has a profound effect starting at the source: the mosquito . . . In the United States, epicenters of transmission have been linked closely to above-average summer temperatures. In particular, the strain of West Nile in the U.S. spreads better during heat waves, and the spread of West Nile westward was correlated with unseasonable warmth. High temperatures are also to blame for the virus jumping from one species of mosquito to a much more urban-loving one, leading to outbreaks across the U.S.”

Real Clear Science came to the same conclusions in a report on August 20. They stated, “The prime culprit in the spread of West Nile is mosquitoes, which transmit the virus to humans when they bite  . . . Climate is a major accomplice, however, according to David Dausey a professor of public health at Mercyhurst College in Erie, Penn. ‘One of the things we’ve worried about for some time is that a changing climate could lead to more mosquito-borne disease,’ he said in an interview. And while you can’t attribute a single outbreak to climate change alone, he said, ‘climate theory tells us that weather extremes will become more common.’ ”

Real Clear Science added that, “Another climate factor that makes for bigger mosquito populations is the fact that spring is coming earlier and winters have been milder in recent years, both of which give insects of all kinds a running start at the breeding season.”

This isn’t the first time theories regarding the connection between climate change and disease have been put forth.

In 2006, The Washington Post  reported, “Global warming—with an accompanying rise in floods and droughts—is fueling the spread of epidemics in areas unprepared for the diseases . . . Mosquitoes, ticks, mice and other carriers are surviving warmer winters and expanding their range, bringing health threats with them.”

“Malaria is climbing the mountains to reach populations in higher elevations in Africa and Latin America. Cholera is growing in warmer seas. Dengue fever and Lyme disease are moving north. West Nile virus, never seen on this continent until seven years ago, has infected more than 21,000 people in the United States and Canada and killed more than 800.”

Wilcox does a good job summing things up: “While the CDC is hesitant to blame this year’s West Nile outbreak on climate change directly, the science is clear. Record-breaking incidences of West Nile are strongly linked to global climate patterns and the direct effects of carbon dioxide emissions. Climate change isn’t just going to screw with the environment, it will continue to have devastating public health implications.”

Do you agree that climate change could be having an effect on the spread of West Nile and other diseases?

Lawrence Karol is a writer and editor who lives with his dog, Mike. He is a former Gourmet staffer and enjoys writing about design, food, travel and lots of other stuff. @WriteEditDream | Email Lawrence | TakePart.com

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