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Record Heat May Have Contributed to a Banner Year for West Nile Virus

Bridget M. Kuehn, MSJ
JAMA. 2012;308(18):1846-1848. doi:10.1001/jama.2012.13495.
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With nearly 4000 cases of West Nile virus reported to the US Centers for Disease Control and Prevention (CDC) as of early October, more than 5 times the number of cases reported in 2011, the 2012 West Nile virus season has been one of the worst since the virus emerged in the United States in 1999.

This surge in cases—which was concentrated in Texas, Mississippi, Michigan, South Dakota, Louisiana, Oklahoma, and California—likely resulted from a confluence of ecological factors, including higher-than-normal temperatures, that may have influenced mosquito and bird abundance, the replication of the virus in its host mosquitoes, and interactions of birds and mosquitoes in hard-hit areas, according to Lyle Petersen, MD, MPH, Director of the CDC's Division of Vector-Borne Diseases. Petersen discussed this year's resurgence of West Nile virus with JAMA.

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Ecological changes likely led to outbreaks of West Nile virus infection in 2012, said Lyle Petersen, MD, MPH, Director of the Division of Vector-Borne Diseases at the Center for Disease Control and Prevention.

(Photo credit: James Gathany/CDC)
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Higher temperatures and moist conditions can promote West Nile virus outbreaks by facilitating mosquito breeding and speeding viral replication.



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