CDC Reports 14 New Cases of Zika Possibly Spread by Sex

February 23, 2016

The Centers for Disease Control and Prevention (CDC), along with state health departments, are studying 14 new cases of Zika infection in the United States that were possibly spread through sex, the agency announced today.

In each of the cases, a man who had traveled to an area with active Zika transmission developed symptoms within 2 weeks of his female sexual partner becoming ill. Several of the women were pregnant, the CDC said in a news release.

The cases of pregnant women catching the virus raised a red flag because Zika is strongly suspected of causing congenital microcephaly, miscarriages, and other adverse fetal outcomes, as well as Guillain-Barré syndrome in adults and children. The World Health Organization has declared the possible link between the Zika virus and microcephaly — on the rise in Brazil – a global public health emergency.

These new reports suggest sexual transmission may be a more likely means of transmission…than previously thought.

Although the Zika virus spreads primarily through mosquito bites, "these new reports suggest sexual transmission may be a more likely means of transmission…than previously thought," the CDC said.

Accordingly, the agency issued an advisory today to state and local officials, public health practitioners and laboratories, and clinicians in its Health Alert Network about the need to follow interim guidance on avoiding sexual transmission of the virus.

The CDC's recommendations followed the discovery earlier this month of a Texas resident who was infected with the virus through sexual relations with a man who had returned from another country where Zika is actively spreading. It was the first instance of local transmission in the United States during the current outbreak, although the CDC reported that a Colorado man may have sexually transmitted the disease to his wife in 2008 after becoming infected in Africa.

In its interim guidance, the CDC urges men who live in, or have visited, an area of active Zika transmission and their pregnant sex partners to use a condom or practice abstinence for the duration of the pregnancy. The CDC asks men to consider taking the same precautions with a sex partner who is not pregnant. It notes that the virus may persist in semen when it is no longer detectable in blood. How long the virus remains in semen is still under study.

There is no evidence that women can transmit the virus to a sex partner, the agency noted in its news release.

In announcing the new reports of possible sexual transmission, the CDC did not identify where they occurred in the United States, or when.

In two of the cases, the virus was confirmed in women "whose only known risk factor was sexual contact with an ill partner who had travelled to an area with local Zika virus transmission," the agency said in its health advisory. Testing for the male sexual partner was pending. For another four women, antibody tests for the virus were positive, but confirmatory tests were pending. The investigation is ongoing in the remaining eight cases, according to the agency.

More Regions Added to Travel Advisory

The CDC today also added the Marshall Islands in the Pacific Ocean and the Caribbean nation of Trinidad and Tobago to its list of countries and territories that pregnant women should avoid visiting on account of active Zika transmission. The region affected by Zika now covers most of Latin American and the Caribbean, as well as various islands in the Pacific and one in the Atlantic Ocean — Cape Verde — off the coast of Africa.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.