Last Updated Feb 2, 2016 6:29 PM EST
Health officials in Dallas say two people there have been diagnosed with Zika virus, including one who was infected through sexual transmission, the first such case documented in the United States. The patient's infection was confirmed by the U.S. Centers for Disease Control and Prevention, CBS DFW reports.
The patient was infected with the virus after having sexual contact with an ill person who recently returned from Venezuela, where Zika virus is being spread by mosquitoes, according to a statement from the Dallas County Health and Human Services (DCHHS).
"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," Zachary Thompson, DCHHS director, said in the statement. "Next to abstinence, condoms are the best prevention method against any sexually-transmitted infections."
Zika virus is primarily transmitted to people through the bite of an infected mosquito. The CDC says that some cases of transmission through sexual contact and blood transfusion have been reported.
The disease, declared a global health emergency by the World Health Organization, has been linked to a surge in the number of babies born with abnormally small heads -- a birth defect known as microcephaly -- in Brazil.
A number of Zika patients there have also developed Guillain-Barré syndrome, a rare autoimmune condition which can cause at least temporary paralysis.
Zika virus symptoms are usually mild and include fever, rash, joint pain, and conjunctivitis. Many people do not exhibit any symptoms at all.
The CDC has issued a travel advisory, urging pregnant women to avoid areas where Zika is spreading -- more than two dozen countries and territories, mostly in Latin America and the Caribbean. All travelers to the region are advised to use insect repellent and take other precautions to avoid mosquito bites.
There is no vaccine for Zika virus and no specific medication to treat it.
"Education and awareness is crucial in preventing Zika virus," said Dr. Christopher Perkins, DCHHS medical director. "Patients are highly encouraged to follow prevention recommendations to avoid transmitting and spreading Zika virus."
There are currently no reports of Zika virus being locally transmitted by mosquitoes in the continental U.S. However, imported cases could potentially spread because the same type of mosquitoes that can transmit the virus live in parts of the U.S., primarily in Southern states.
Health officials are urging recent travelers with Zika virus and those who have Zika-like symptoms to protect themselves from further mosquito bites, and people should avoid sexual contact with someone who has Zika virus. The virus is detectable in a person's blood and can be transmitted for about a week after infection, officials say.