(CN) - A Texas county has the first U.S. case of the Zika virus being transmitted through sexual contact, federal health officials confirmed Tuesday.
Dallas County health officials said the patient - whom officials declined to identify citing privacy concerns - got the virus from someone infected by a mosquito in Venezuela. Centers for Disease Control and Prevention did testing that confirmed the news to Dallas officials Tuesday.
It's the first case of the virus being transmitted in the United States. Seven people in the Houston area have tested positive, but they were all infected while traveling in warmer climates in Latin America.
"CDC has confirmed through laboratory testing the first U.S. case of Zika virus infection in a non-traveler in the continental United States," the CDC said in a statement. "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. In this instance there was no risk to a developing fetus."
The World Health Organization declared Zika a public health emergency on Monday, and estimates the virus will spread throughout the Western Hemisphere and infect up to 4 million people by 2017.
Zika is transmitted by the Aedes mosquito, which inhabits warm climates throughout the Western Hemisphere, and the insects can only catch the virus by biting an infected human.
The disease has spread rapidly across Latin America, leading to 4,000 suspected cases across 25 nations and territories. It was previously assumed that the virus was only transmittable through mosquito bites, and cases across the world have so far stemmed from travelers visiting affected regions.
The development poses a new risk for U.S. citizens who haven't traveled to affected areas of the globe, since they were previously presumed to be safe from contracting the Zika virus.
Dallas County Health and Human Services director Zachary Thompson pledged to educate the public about the virus that's been linked by experts as the possible cause for 3,000 babies born with microcephaly in Brazil in 2015. Babies with microcephaly are born with abnormally small heads and developmental delays.
"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. Next to abstinence, condoms are the best prevention method against any sexually transmitted infections," Thompson said in a statement.
This case also highlights the lack of firm understanding that agencies and doctors have about the disease. It is unknown how long the Zika virus lasts, if it is in fact connected to microcephaly, and the full spectrum of transmissions methods.
"Based on what we know now, the best way to avoid Zika virus infection is to prevent mosquito bites," the CDC said. "We do not have definitive information on the infectious time period, and will provide more guidance for individuals and clinicians as we learn more."
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