Confirmed cases of the Zika virus, a mosquito-transmitted illness related to yellow fever and dengue and linked to microcephaly, have been growing rapidly.
The illness first rose to attention in Brazil in April 2015 after the discovery of an epidemic of a birth defect in which children were born with smaller than normal cerebrums. Since then, the virus has been been found in more than 20 countries in Latin America alone. In January 2016, the CDC released an extensive list of countries pregnant women should not travel to in order to prevent contracting the illness.
World Health Organization director general Dr. Margaret Chan referred to the spread of the virus as "explosive" and said Zika had gone "from a mild threat to one of alarming proportions." Some even compared it to the Ebola epidemic.
The number of reported cases in the U.S. began to grow by the end of January. At least 30 people were confirmed to have the virus in states like Texas, Massachusetts, Arkansas, New York, Hawaii and Virginia.
But here's why Americans don't need to be fearful that Zika will plague the U.S. just yet: Everyone that has been diagnosed with a Zika infection contracted it while traveling abroad. There have been no cases in which the virus has been transmitted locally.
"We're expecting a lot of travel-associated cases," Anne Schuchat, principal deputy director for the CDC, said on Thursday.
Another thing to consider: The virus is spread by Aedes mosquitoes, which are mostly found in tropical and subtropical regions. In the countries where Zika is spreading rapidly, people can contract the virus in their homes, where the mosquitoes like to dwell. Many Latin American homes don't have air-conditioning; people leave their windows people for fresh air, an invitation for the insects. Plus, more trash in Latin American cities means more opportunities for standing water to collect, creating the perfect breeding grounds for the mosquitoes. In the U.S., most people have screens on windows and doors and air-conditioning.
"(The Aedes mosquitoes) is a bit of a homebody," infectious disease expert Daniel Lucey of Georgetown University told BuzzFeed News.
