A woman might have passed the Zika virus to her male partner during sex, contradicting previous thinking that male sexual partners spread the virus, New York City's Department of Health and Mental Hygiene and the Center for Disease Control and Prevention said Friday.
Zika is usually spread by mosquitoes, and health officials have known for some time that men can spread it through sex.
After corroborating the histories, health officials concluded that "the timing and sequence of events support female-to-male Zika virus transmission through condomless vaginal intercourse". There have now been 1,305 travel-related cases of Zika reported in the United States, and 14 known cases of sexually transmitted Zika in the USA, per CNN.
The number of Zika virus cases in Florida now tops 300, with 18 new cases reported Friday, a record for a single day.
Most of those who get infected with the virus do not get sick, or only develop mild illness but the virus can cause serious problems in pregnant women and their unborn child.
The CDC has recommended that pregnant women avoid travel to areas with ongoing Zika transmission.
"Findings from the study will help health officials refine recommendations for preventing spread of Zika virus through sexual transmission", Fowlie said.
She had headache and abdominal cramping while in the airport awaiting return to the US and developed symptoms including fever, fatigue, a maculopapular rash and back pain the following day.
Six days after having sex, the woman's partner also developed symptoms of Zika, and he went to the same doctor that the woman had seen. He, too, was diagnosed with a Zika infection based on laboratory tests.
Investigators concluded that the virus, either in the woman's vaginal fluids or menstrual blood, was transmitted to the man. The report provides the first documented proof that the virus can be transmitted through vaginal fluid.
Scientists only confirmed in February that virus could be spread through sex, and the head of the CDC, Dr. Tom Frieden, has acknowledged the disease remains relatively unstudied.
Most sexually transmitted diseases "are transmitted both from men to women and women to men", Brooks noted. In each of these cases, the virus was contracted while patients were visiting other countries where active Zika transmission is taking place via mosquito bites.
Male-to-female transmission is considered far more likely than the other way around, experts said. Her male partner, who had not been overseas or exposed to mosquitoes, developed the virus seven days later.
This new kind of transmission could affect guidelines about stopping the sexually transmitted Zika infections.
In the NY case, for example, several factors lined up to allow the disease to spread.