MIAMI _ The Centers for Disease Control and Prevention on Friday reported the first suspected case of Zika by sex transmitted from a woman to a man, underscoring how much scientists still need to learn about the virus and the ways it can spread.
The case was announced on the same day that Florida health officials confirmed 18 new cases of Zika virus infection _ the most in a single day _ raising the statewide total to 311 people affected this year. Miami-Dade leads all counties with 84 cases reported; Broward has 43.
Friday capped the state's busiest week of Zika infections this year, with 48 new cases reported, but there have been no cases of mosquito-borne transmission in Florida or any other state.
Mara Gambineri, communications director for the Florida Department of Health, said the spike in cases might be because of "enhanced testing and lab capacity, including the advent of commercial testing, increased travel in the summer when in many places it is mosquito season, and increased awareness among medical providers."
The CDC recommends testing for any person with two of the four most common symptoms _ fever, joint pain, rash and red eyes _ and a travel history to a Zika-infected area. The federal agency also recommends testing for all pregnant women with a travel history, or a partner with travel history, to any area where Zika is transmitted by mosquito bites.
The first sexually transmitted case from a woman to a man was discovered by the New York City health department during a routine investigation. A woman in her 20s reported she had engaged in a single event of sexual intercourse with a man on the day she returned from traveling to an undisclosed area with ongoing Zika transmission.
According to the CDC, the man did not use a condom, and he developed a fever, rash, joint pain and red eyes seven days later.
It's the first reported case of female-to-male sexual transmission of Zika virus. There had been previous confirmed cases of sexual transmission from men to women.
More research is needed to determine the risk of a woman transmitting Zika virus to her sexual partners, according to the CDC, which urged medical professionals to report any patients who have Zika-like symptoms but no recent history of travel to an area with ongoing transmission of the virus.
People who want to reduce the risk for sexual transmission of Zika virus should abstain from sex or correctly and consistently use condoms as recommended by the CDC.