The latest on Zika, the mosquito-borne illness raising concern around the world.  

By Brigitt Earley
Updated February 04, 2016
Credit: Grant Cornett

Concerns continue to grow over the Zika virus, as more countries are added to the Centers for Disease Control’s (CDC) travel advisory and the World Heath Organization (WHO) declares the outbreak “an international public health emergency”—only the fourth such declaration in the WHO’s history.

Dr. Michael Angarone, D.O., an infectious diseases specialist with Northwestern Medicine, tells that the infection is “relatively benign for the overwhelming majority of us.” But the WHO still cites “a recent cluster of microcephaly cases and other neurological disorders reported” as a Public Health Emergency of International Concern.

In Texas, reports of transmission via sexual contact, most likely from semen, caused the CDC to change their recommendations for travelers visiting regions where the Zika virus is present. In addition to taking precautions to prevent mosquito bites in the first place—wearing long sleeves, using insect repellant, and staying in indoor and air-conditioned spaces—the CDC now recommends using condoms to prevent sexual transmission, as well.

If you’re going to have sexual contact with someone who has traveled to the affected areas, you should either refrain or wear a condom, says Angarone. Especially considering that “up to two-thirds of people may not have symptoms (or they may be very mild).”

Previous studies have shown that the virus persists for about a week in blood and for another five to 10 days in urine, says Angarone, but “we don’t know how much longer it may persist in semen.” The CDC did not offer guidelines for how long after travel men and women should abstain from sex or use condoms.

At this time, Angarone recommends travelers visiting countries listed in the CDC travel advisory be evaluated by a physician upon return to the United States. Though “it’s unclear when—or if—we are going to see local transmission of the virus, we know the type of mosquito [that carries the Zika virus] is in the United States.” Therefore, no matter where you are, “the biggest thing is to just continue to protect yourself against mosquito bites.”