If confirmed, this development could seriously complicate efforts to control the spread of the disease, which health officials suspect causes birth defects in children whose mothers were infected during pregnancy.
The disease has spread in Brazil and other tropical climates, primarily through mosquito bites, including those by a species that thrives in the southern and western United States: aedes aegypti. It’s still winter in the United States, but some are readying for the day when the airborne pests move the disease north.
Still, experts believe a widespread outbreak across the United States is unlikely. They note that the mosquitoes only thrive in tropical areas, and that the prevalence of air conditioning, window screens and the expected abatement efforts by local governmental agencies will reduce their threat.
The mosquitoes’ habitat may seem small geographically compared the country as a whole, but it does includes about one in five American counties. They are home to roughly 80 million people, according to a Orkin Termite Control analysis of data released by the mapping company Esri and the U.S. Census Bureau.
The rough map below shows the species’ habitat (shaded in pink) and its respective counties’ population density (red dots represent 50,000 residents). The area includes roughly 29 million households — some of which, of course, will include pregnant women this summer.