Climate Change to Spread West Nile Virus, Study Says

Annie Hauser
Published: September 9, 2013

Climate change will affect the spread of West Nile virus and other vector-borne, disease ecologists believe, but exactly how differs from region to region, researchers say in the Proceedings of the National Academy of Sciences.

Under current climate change models, many locations will see longer mosquito seasons because of warmer temps. (Now, West Nile season is from April to September.) But hotter, drier summers will be harder on the mosquito population, shrinking the summer numbers of disease-carrying insects, researchers at the University of Arizona found, based on a new model of the mosquito population.

(MORE: Eye-Opening Effects of Climate Change)

Summer weather’s affect on the mosquito population will vary depending on temperature and precipitation — population declines are expected to be significant in the South, but not further north, for example.

Disease-transmission studies and programs designed to control populations of disease-carrying mosquitos must then be targeted locally to maximize their effectiveness, the authors said in the study.

(MORE: How Climate Change Already Affects Your Health)

The hot, dry summer of 2012 contributed to the worst West Nile season on record, according to the U.S. Centers for Disease Control and Prevention. Last year, 243 people died from the virus and another 5,500 were sickened by the disease, which was found in every state in the continental United States, according to CDC data. 

In comparison, so far this year, West Nile has yet to reach every state and 13 individuals have died from complications of the disease. Encephalitis, inflammation of the brain, or meningitis, inflammation of the brain and spinal cord, are the two most severe effects of West Nile and occur in less than 1 percent of patients, according to the CDC.

MORE: Diseases You Can Get from Mosquitos and More

Summer is the season for insect-borne diseases, which sicken tens of thousands every year. Here, the host of mosquito, tick and other insect-borne diseases that strike in the United States, and what to watch for. All of the following information is from the CDC. (James Jordan/Flickr)


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