Mosquitoes that transmit the Zika virus live in nearly all of the continental United States, according to new maps released by the Centers for Disease Control and Prevention (CDC). The maps show that two breeds of virus-carrying mosquitoes—Aedes aegypti and Ae. Albopictus—can be found as far north as Michigan, New Hampshire, and Washington state. The mosquitoes are concentrated most heavily in the Southeast and Southwest.
Ae. albopictus (also known as the Asian tiger mosquito), which lives in semirural settings, was captured at least once in 40 states, whereas Ae. aegypti (also known as the yellow fever mosquito), which prefers urban areas, was found in 26 states, the CDC said. Overall, the mosquitoes were found in approximately one-third of the 3,141 counties in the United States.
As of June 8, 2016, there have been 691 traveled-associated cases of Zika virus infection (ZVI) in the U.S., but no locally acquired vector-borne cases, according to the CDC. On the other hand, in U.S. territories (Puerto Rico, American Samoa, and the U.S. Virgin Islands), 1,301 cases of locally acquired vector-borne ZVI have been reported, along with four travel-related cases.
In the continental U.S, only four states have not had laboratory-confirmed cases of ZVI: Alaska, North Dakota, South Dakota, and Wyoming.
On February 1, 2016, the World Health Organization declared a public health emergency of international concern (PHEIC) because of clusters of microcephaly and other neurological disorders in some geographic areas affected by the Zika virus. On February 8, the CDC elevated its response efforts to level-1 activation, the highest response level at the agency.
In related news, the federal government has announced plans to release a 60-page “blueprint for action” to spearhead the nation’s response to the Zika threat. Health experts don’t expect explosive Zika virus transmission in the U.S. because many homes are air-conditioned and keep their windows closed. The experts worry, however, that an outbreak could be difficult to fight since 80% of infected individuals do not experience symptoms.
As a key feature of the government’s response plan, multidisciplinary teams will provide state and local officials with technical and logistical expertise, epidemiologic data, laboratory services, and advice on eliminating virus-carrying mosquitoes. The CDC has used similar rapid-response teams for years to combat a variety of diseases.