DALLAS — The Dallas County Health and Human Services Department has confirmed two people in the county have tested positive for Zika virus.

One patient had sexual contact with another infected individual; the other patient contracted the virus while in Venezuela.

According to the DCHHS, the Centers for Disease Control and Prevention confirmed the sexually-transmitted infection Tuesday. That patient had sexual contact with an individual who was ill and had recently returned from Venezuela, where the virus was present.

One of the two Zika virus cases in Dallas County was traced to an individual who had recently visited the South American country of Venezuela. (WFAA)
One of the two Zika virus cases in Dallas County was traced to an individual who had recently visited the South American country of Venezuela. (WFAA)

Although scientists have known for some time that Zika can be transmitted through sex, the vast majority of cases are spread through the bite of infected mosquitoes, much like malaria or West Nile virus.

“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.”

Zika virus is transmitted to people by mosquitoes and through sexual activity, according to DCHHS. The most common symptoms of Zika virus are fever, rash, joint pain, and conjunctivitis (red eyes). The illness is usually mild, with symptoms lasting several days to a week.

On Monday, the World Health Organization declared the rise in birth defects linked to the Zika virus outbreak a public health emergency, underscoring the seriousness of the problem and paving the way for more money, greater attention and a coordinated global response.

Doctors connect Zika, which is spread by mosquitoes, to a surge in neurological disorders and the birth defect microcephaly, in which infants are born with abnormally small heads and incomplete brain development. WHO officials say clusters of these problems – not the Zika virus itself, which usually causes mild illness – led to the declaration of a "public health emergency of international concern."

Zika virus in Venezuela
<p><span style="color: rgb(102, 102, 102); font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif; font-size: 10.8px; line-height: 16.2px;">A Venezuelan Health Ministry employee fumigates against Aedes Aegypti mosquito in Caracas on January 28, 2016. (Juan Barreto/AFP/Getty Images)</span></p>

There is currently no vaccine or treatment for the Zika virus.

DCHHS advises individuals with symptoms to see a healthcare provider if they have visited an area where Zika virus is present or had sexual contact with a person who traveled to an area where Zika virus is present.

Although more than 30 Americans have been diagnosed with Zika, these have largely been travel-related cases, which pose a relatively low risk for spreading.

The continental USA is not considered to have a Zika outbreak because the virus has not become entrenched in the mosquitoes that cause the illness.

The county health department also recommends reducing your chances of mosquito bites using the same tactics as West Nile virus season:

  • DEET All Day, Every Day: Whenever you’re outside, use insect repellents that contain DEET or other EPA approved repellents and follow instructions.
  • DRESS: Wear long, loose, and light-colored clothing outside.
  • DRAIN: Remove all standing water in and around your home.
  • DUSK & DAWN: Limit outdoor activities during dusk and dawn hours when mosquitoes are most active.

USA TODAY contributed to this story.