Are Zika-carrying mosquitoes in your area? Check this map

John Murphy, MDLinx | June 16, 2016

Are Zika-bearing mosquitoes coming your way—or are they already in your area? In the past two decades, the mosquito believed to be the primary carrier of Zika (Aedes aegypti) has expanded its territory from the Southwest and Southeast to the Mid-Atlantic states and as far north as New England, according to the latest report published June 9, 2016 in the Journal of Medical Entomology.

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Where is zika virus occurring in the US? CDC report identifies mosquitoes with Zika in 183 counties

This map (click to enlarge) shows the reported occurrence of the Zika-carrying Ae. aegypti mosquito by U.S. county. (Image: Entomological Society of America)

As shown on the map, which is current as of March 2016, Ae. aegypti has now been found in 183 counties from 26 states and the District of Columbia.

“Sporadic contemporary collections of Ae. aegypti along the Mid-Atlantic Coast are not surprising, as this mosquito historically caused yellow fever outbreaks as far north as New York and Boston,” the authors wrote in their study. “Perhaps the most concerning development for Ae. aegypti is its establishment in the Southwest, most recently in California in 2013.”

The study is based on records from the Centers for Disease Control and Prevention’s (CDC) ArboNET database, VectorMap, the published literature, a survey of mosquito control agencies, university researchers, and state and local health departments.

The report also documents the increasing occurrence of Aedes albopictus, which is known to carry the dengue virus. This species was found in 1,241 counties from 40 states and Washington, D.C.

“Our findings underscore the need for systematic surveillance of Ae. aegypti and Ae. albopictus in the United States, and delineate areas with risk for the transmission of these introduced arboviruses,” the authors wrote.

This report isn’t exactly a mosquito census though. It includes only those counties in which the mosquitoes were identified, but not all counties have surveillance programs.

“So just because a county hasn't reported having any Ae. aegypti mosquitoes doesn't mean they're not there,” said study co-author John-Paul Mutebi, PhD, an entomologist at the CDC, in an NPR article.

Ae. aegypti isn’t a newcomer to the U.S.—it’s been around since the 17th century. It’s the suspected vector of the yellow fever and dengue outbreaks that occurred in the eastern U.S. from 1650 to the early 20th century, the authors noted.

However, modern improvements—changes to ship design and sailing patterns, urban improvements (particularly piped water supplies), use of window screens, and mosquito control efforts—have limited virus epidemics in the U.S., the researchers explained.

Thus, “large outbreaks of arboviruses transmitted by Ae. aegypti and Ae. albopictus are unlikely to recur in the continental United States unless socioeconomic conditions deteriorate to mimic those seen in previous centuries or if other modes of transmission for these viruses became more widespread,” the authors concluded.

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