Zika virus is transmitted by the mosquito species Aedes aegypti, also a carrier of dengue fever and chikungunya, two other tropical diseases. 

Though Aedes aegypti is not native to North America, researchers at the University of Notre Dame who study the species have reported a  population of the mosquitoes in a Capitol Hill neighborhood in Washington, D.C. The team noted that they have identified genetic evidence that these mosquitoes have overwintered for at least the past four years, meaning they are adapting for persistence in a northern climate well out of their normal range.

While the Washington population is currently disease-free, Notre Dame Department of Biological Sciences professor David Severson, who led the team, said in a prepared statement that the ability of this species to survive in a northern climate is troublesome. This mosquito is typically restricted to tropical and subtropical regions of the world and not found farther north in the United States than Alabama, Mississippi, Georgia and South Carolina.


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“What this means for the scientific world,” said Dr Severson, who led the team, “is some mosquito species are finding ways to survive in normally restrictive environments by taking advantage of underground refugia. Therefore, a real potential exists for active transmission of mosquito-borne tropical diseases in popular places like the National Mall. Hopefully, politicians will take notice of events like this in their own backyard and work to increase funding levels on mosquitoes and mosquito-borne diseases.”

Officials with the World Health Organization announced this week that Zika virus is expected to spread across the Americas and into the United States.

 Reference:

1. Lima A, Lovin DD, Hickner PV, Severson DW. Evidence for an Overwintering Population of Aedes aegypti in Capitol Hill Neighborhood, Washington, DC. Amer J Trop Med Hygiene, 2015; 94 (1): 231 DOI: 10.4269/ajtmh.15-0351.