A Dallas County resident has become the first Zika patient to contract the virus in the U.S. without traveling abroad, according to the Centers for Disease Control and Prevention. County health officials said the patient was infected through sexual contact, not through a mosquito bite.
Dallas County Health and Human Services said the patient was infected after having sexual contact with an individual who developed symptoms after returning from a trip to Venezuela. The individual from Venezuela is also infected with the virus. Both patients have fully recovered from the infection, health officials said Wednesday.
"A person who recently traveled to an area with Zika virus transmission returned to the United States and developed Zika-like symptoms. The person later tested positive for Zika, along with their sexual partner, who had not traveled to the area," the CDC said in a statement.
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Neither is pregnant. Both are thought to still be in Dallas County.
DCHHS said Tuesday that the CDC confirmed the Zika test and that the county health department confirmed the virus was transmitted sexually through a follow-up interview with the patient. The CDC’s statement did not confirm or rule out that the virus was transmitted sexually.
“Now that we know Zika virus can be transmitted through sex, this increases our awareness campaign in educating the public about protecting themselves and others,” said Zachary Thompson, DCHHS director. “Next to abstinence, condoms are the best prevention method against any sexually-transmitted infections.”
The Zika virus is usually spread through mosquito bites. The CDC previously said it was aware of reports of the virus being spread through sexual contact, but had not confirmed the transmission method. While exploring the possibility the virus could be spread through sex, investigators found the virus in one man's semen in Tahiti, and there was report of a Colorado researcher who caught the virus overseas and apparently spread it to his wife back home in 2008, according to The Associated Press.
There are no reports of the virus being spread locally by mosquitoes, though local transmission by mosquitoes is possible with the virus now known to be in North Texas, according to the county. Dr. Jeffrey Kahn, with the University of Texas Southwestern Medical Center and Children's Health, said infected people could infect the mosquitos and "start the transmission cycle."
"And once that occurs, it's almost impossible to get the virus out of the population," he said.
Common symptoms of Zika virus include fever, rash, joint pain, and conjunctivitis (red eyes). The illness is usually mild with symptoms lasting several days to a week, Dallas County health officials said.
Those with symptoms, or those who have had sexual contact with someone who has symptoms, are urged to seek immediate medical care, to protect themselves from further mosquito bites and to avoid unprotected sexual contact.
The CDC said it has no definitive information on the infectious time period and will provide more guidance as it learns more about the virus.
There is no medication to treat Zika virus and there is no vaccine; the best prevention is to avoid mosquitoes and sexual contact with infected people. The recommendations for avoiding the Zika virus are the same for avoiding West Nile virus.
- Dusk and Dawn: Stay inside if possible — mosquitoes are most active during dusk and dawn.
- Dress in long sleeves, pants when outside: For extra protection, spray thin clothing with repellent.
- DEET: Make sure this ingredient is in your insect repellent.
- Drain standing water in your yard and neighborhood: Mosquitoes can develop in any water stagnant for more than three days.
Additionally, the CDC continues to recommend that pregnant women and women trying to become pregnant take the following precautions:
- Pregnant women should consider postponing travel to the areas where Zika virus transmission is ongoing. Pregnant women who must travel to one of these areas should talk to their doctor or other healthcare professional first and strictly follow steps to avoid mosquito bites during the trip. Pregnant women should also avoid exposure to semen from someone who has been exposed to Zika virus.
- Women trying to become pregnant should consult with their healthcare professional if their partner has had exposure to Zika virus.
To date, there are seven other confirmed Zika cases in Texas, in Houston and Harris County. In each of those cases, the patient had traveled abroad to an area where Zika is present.
NBC 5's Kevin Cokely, Holley Ford and Todd L. Davis contributed to this report.