The Centers for Disease Control and Prevention (CDC) today released the first solid evidence that a man infected with Zika, but who never develops symptoms, can sexually transmit the virus to a female partner.
An article published online in the agency's Morbidity and Mortality Weekly Report (MMWR) described the case of a woman who contracted Zika after having condomless vaginal intercourse and fellatio with a male partner after he came back from the Dominican Republic, where mosquitos are spreading the virus. The man said he had been exposed to mosquitos during his travels, but had not experienced fever, rash, conjunctivitis, or other hallmarks of Zika before or after returning to the United States. He said he had felt fatigued, but chalked that up to travel.
The man subsequently tested positive for antibodies against both Zika virus and dengue virus. The woman, who developed fever, rash, and other Zika symptoms, tested positive for Zika virus RNA in her urine.
The authors of the MMWR article, except for one CDC investigator, were public health officials in Maryland, where the case came to light.
It is already known that the Zika virus can be sexually transmitted by infected men who are symptomatic. However, most people who are infected with Zika do not experience symptoms.