The U.S. Centers for Disease Control and Prevention has confirmed a Zika virus case in Texas that was acquired through sexual transmission.

"Dallas County Health and Human Services (DCHHS) has received confirmation from the Centers for Disease Control and Prevention of the first Zika virus case acquired through sexual transmission in Dallas County in 2016," a statement from the county said.

The county said that a patient was infected with the virus after having sexual contact with an ill individual who returned from a country where Zika virus is present.

The patient had not travelled to area.

A statement sent to CTV News from the CDC on Tuesday said the patient was the first case of the Zika virus in a "non-traveller in the continental United States."

The CDC added that in this case there was no risk to a "developing fetus."

DCHHS director, Zachary Thompson, said that the new case has prompted the organization to emphasize its public awareness campaign.

He added that condoms are the "best prevention method against any sexually transmitted infections."

The CDC also advised people to avoid exposure to semen from someone who has been exposed to the Zika virus or has been ill from the Zika virus infection.

"Based on what we know now, the best way to avoid Zika virus infection is to prevent mosquito bites," said Benjamin Haynes, senior press officer for the CDC, in the statement.

"We do not have definitive information on the infectious time period, and will provide more guidance for individuals and clinicians as we learn more."

This isn’t the first time the Zika virus has been linked to sexual transmission.

A 2011 study looked at two cases of the virus in U.S. scientists who lived in Senegal while they were performing a mosquito-sampling project.

After both were bitten by mosquitoes, they returned home to Colorado and fell ill sometime between six and nine days later.

One of the scientists experienced hematospermia, or blood in his semen, and his wife, who had never been to Africa or Asia, also contracted the virus.

"Circumstantial evidence suggests direct person-to-person, possibly sexual transmission of the virus," the study says.

In addition to sexual transmission, the virus is spread to humans by a species of mosquito known as Aedes aegypti.

On Monday, the World Health Organization declared the spread of the virus a global emergency.

Researchers are investigating a possible link between the virus and a spike in the number of babies born with microcephaly in Brazil, since the virus was discovered there last year.

Babies with microcephaly are born with unusually small heads, and can go on to have incomplete brain development.

The CDC advised pregnant women and women who trying to become pregnant to take the following precautions until "more is known" about the virus.