Authorities on Tuesday confirmed the first case of someone being infected with Zika virus in the United States via sexual transmission.
The case, in Dallas County, Texas, occurred when someone recently traveled to a country with Zika virus, and then returned to the U.S. and transferred the virus to their sexual partner.
{mosads}The case is a rare instance of the virus being transmitted through sex, as it is usually spread through mosquito bites.
The Centers for Disease Control and Prevention (CDC) said Tuesday that sexual transmission is also a risk, although it does not have “definitive information.”
“Based on what we know now, the best way to avoid Zika virus infection is to prevent mosquito bites AND to avoid exposure to semen from someone who has been exposed to Zika virus or has been ill from Zika virus infection,” the CDC said in a statement.
It recommended that people use condoms to prevent the spread of the infection.
There had previously been Zika cases in the United States — about 31 as of last week — but the people had all been infected while traveling, not in the United States.
Dr. Anne Schuchat, deputy director of the CDC, told reporters last week that there had been reported cases of the virus being transmitted through sex, but that “the science is very clear that it’s primarily through an infected mosquito.”
The virus has been spreading rapidly in South America, but U.S. officials have said they expect only “limited” outbreaks in the United States.
They pointed to other mosquito-borne viruses being limited to areas like the southern tips of Florida and Texas, but said the U.S. is remaining vigilant nonetheless.
Senate Majority Leader Mitch McConnell (R-Ky.) said Tuesday that he discussed preparedness for the virus with President Obama during a meeting at the White House.
“We need to get out in front of the Zika virus to make sure that we don’t end up, you know, having the kind of feeling across the country that we’re sort of reacting too late, like we did on Ebola,” he said.