Zika can be transmitted by sex, CDC says, as viral infections rise in Florida

Two additional Zika infections were confirmed in Florida on Friday, raising the statewide total to 20 reported cases, including seven in Miami-Dade and three in Broward counties, the Department of Health said.

As Zika infections continued to rise in Florida and other states, the nation's top agency for combating infectious disease issued a new warning about the virus — advising Americans that Zika can be transmitted by a man to his sex partners.

“Sexual transmission of Zika virus is possible, and is of particular concern during pregnancy,” said the advisory published by the Centers for Disease Control and Prevention.

The CDC advises men who might have been exposed to Zika to consider abstaining or using a condom.

Zika is primarily transmitted by Aedes aegypti mosquito bites, though spread of the virus also has been reported through blood transfusions.

As of Feb. 10, the CDC had confirmed 52 Zika cases in 16 states and the District of Columbia. In Florida and other states, all Zika infections were acquired outside the country, health officials reported.

None of the Florida cases involves pregnant women, who are considered to be at greatest risk because of a suspected link between Zika virus and microcephaly, a birth defect. The CDC has not reported whether any Zika cases in other states involve pregnant women.

Anticipating the first locally acquired infection, the Florida health department activated a Zika information hotline on Friday (855-622-6735) offering daily updates and answers to questions from the public.

“We have made it a priority to stay ahead of the possible spread of this virus in Florida,” Gov. Rick Scott said in a written statement announcing the hotline.

According to CDC travel advisories, Zika virus is present in Mexico, the Caribbean, Central America and South America. The virus is also present in Cape Verde and in the Pacific Islands.

Zika illness is usually mild with symptoms including a rash, fever, joint pain and red eyes that last from several days to a week. But as Zika spread during the last year through South America and the Caribbean, there have been reports of a spike in microcephaly in babies born to mothers infected with the Zika virus while pregnant.

Scientists are still working to determine whether there is a conclusive link between the virus and microcephaly and other neurological disorders.

The CDC is advising pregnant women to avoid travel to countries where the virus is spreading. Women who are already in those countries should take precautions to protect themselves from mosquitoes.

The CDC’s advisory on the sexual transmission of Zika is based on three cases.

The first is a widely reported case in Colorado, in which a researcher returning from a trip to Senegal inadvertently infected his wife in 2008.

The second case is currently under investigation by public health officials in Dallas County, Texas. It is believed to have been transmitted to an unidentified person who had sex with a partner who had returned from Venezuela and fallen ill with Zika.

The third case did not involve an actual case of sexual transmission. Rather, researchers reported finding “replication-competent Zika virus isolated from semen at least two weeks and possibly up to 10 weeks after illness onset,” according to the CDC.

The man in the third case had no sexual contacts, the CDC said, adding that “because no further testing was conducted, the duration of persistence of Zika virus in semen remains unknown.”

The CDC does not recommend testing of men to assess risk for sexual transmission of Zika.

Despite the latest advisory, physicians and researchers still do not have all the answers on how the virus may be spread. In all three cases cited by the CDC, the men developed symptomatic illness. But four out of five people infected with Zika show no symptoms.

Whether infected men who never develop symptoms can transmit Zika virus to their sex partners is unknown, the CDC said. Sexual transmission of Zika virus from infected women to their sex partners has not been reported.

There is no vaccine for Zika. And while public health officials advise anyone concerned about contracting the virus to use insect repellants, such as DEET or Permethrin in clothing, the CDC now adds that it’s also advisable to avoid sex or use condoms when having sex with someone who has recently traveled to a country where Zika is present.

This story was originally published February 12, 2016 at 12:27 PM with the headline "Zika can be transmitted by sex, CDC says, as viral infections rise in Florida."