Sexual Transmission of Zika "More Common Than Previously Reported"

By Kelly Young

Edited by André Sofair, MD, MPH, and William E. Chavey, MD, MS

The CDC provided details in MMWR on Friday of nine women who had confirmed Zika infection during pregnancy after recent travel outside the U.S. and 14 possible cases of sexual transmission.

Two pregnancies resulted in fetal loss, two ended in elective termination, two infants were born healthy, one infant had severe microcephaly at birth, and two pregnancies are continuing with no known complications. All adverse outcomes occurred in women with Zika symptoms in the first trimester. (The CDC has launched a registry of pregnant women with Zika infection.)

As we reported earlier this week, the CDC has identified 14 potential U.S. cases of sexual transmission of the virus to women from February 6 to 22. Two have been laboratory confirmed, and four cases are probable. In these women, their only identified risk factor was having had sex with a symptomatic man who'd recently traveled to a region with known Zika transmission. Two potential cases have been ruled out, and results for six others are pending.

The authors write: "The cases described here suggest that sexual transmission of Zika virus is more common than previously reported."

They add: "Health care providers should now consider any person who has had condomless sex (i.e., vaginal intercourse, anal intercourse, or fellatio) with a male partner who has traveled to an area of ongoing Zika virus transmission and who has had symptoms of Zika virus disease during travel or within 2 weeks of return as potentially exposed."

As of February 24, there have been 107 cases of travel-related Zika infection in the U.S; Puerto Rico has 117 known diagnosed cases (most acquired locally).