Public health officials in Dallas have confirmed a sexually transmitted case of zika virus, marking the first time the virus has been contracted on US soil during the current outbreak.
After arriving in the Americas last spring, concern over the zika virus rose when officials in Brazil noted a sudden surge in the number of cases of microcephaly—a congenital defect that prevents the brain from developing normally—in newborns. The link between the brain defects and the virus has not been confirmed, but the association caused enough alarm that the World Health Organization declared the spread of zika a public health emergency.
The Dallas case is technically the official arrival of the virus in the country because it's the first time, in this outbreak, zika has been contracted on US soil. However there have already been multiple cases of zika reported on US soil from Americans who travelled abroad and returned home. The news is also noteworthy because it lends further evidence to the previously-held suspicious that zika can be transmitted through sexual intercourse, not just through person-to-mosquito-to-person transmission. But it's not the first case like this.
Back in 2011, there was a case of suspected sexual transmission of zika documented in Colorado, and acase in Tahiti found active zika virus in a man's semen. So what does it all mean? Should we be worried?
For one, it's still not likely that zika is about to sweep the nation, in part due to the fact that it's too cold for the mosquitoes that transmit zika to survive in most of the country. A single confirmed case also doesn't tell us how high the risks of sexual transmission are. It does, however, lend pretty solid evidence that the virus can, in some instances, be transmitted through intercourse, which just adds to the mountain of questions researchers are scrambling to answer.
But it's important to remember what we don't know. The link between zika and microcephaly, has not been confirmed, nor has the possible link to a rare neurological condition called Guillain-Barré syndrome. We do know that about four out of five people who are infected with zika don't even get sick, and those who do usually only have mild, flu-like symptoms for a week or so. That may be reassuring if you're not pregnant, but for expectant mothers, the lack of information and confusion over zika is frustrating and frightening. Documenting cases like the one in Dallas gives researchers more information to work with to help us understand the risks of this rapidly-spreading virus.