A case of Zika virus infection transmitted by sex, rather than mosquito bite, was reported in Texas on Monday.
The Dallas County Health and Human Services Department reported that a patient with Zika virus was infected after having sex with an ill individual who had returned from Venezuela, where Zika was circulating.
No other identifying information was given.
"This increases our awareness campaign in educating the public about protecting themselves and others," said Zachary Thompson, the health department director, in a prepared statement. "Next to abstinence, condoms are the best prevention method against sexually transmitted infections."
Scientists have suspected that Zika could be transmitted sexually. In 2008, a malaria specialist who caught Zika virus while gathering mosquitoes in Africa passed the infection to his wife shortly after his return to northern Colorado.
Because his wife had not left the state and there were no mosquitoes in the region capable of carrying Zika — and because the couple did not infect any of their four children — experts concluded the only logical explanation was transmission through sex.
In 2013, French scientists found viable Zika virus in the semen of a man who had recovered from the infection. They could not determine how long it had persisted, because he had had more than one episode of fever that year that might have been related to Zika virus.