Rare sexually transmitted case of Zika virus detected in Texas

Texas health officials have reported the first case in which the Zika virus, which has been rapidly spreading throughout Central and South America, had been transmitted to a non-traveler in the U.S. since a fast-moving outbreak of the virus began sometime in 2015.

According to the Dallas County Health and Human Services, the case involves a non-traveler in Texas who had sex with a partner who had recently returned from Venezuela and showed symptoms consistent with the Zika virus. 

It has been suspected that in some cases, Zika could be transmitted sexually, however that had only been confirmed in one case in 2008.

"Case details are being evaluated, but the possibility of sexual transmission from an infected person to a non-infected person is likely in this case," the County department said in a press release.

In an email to Mashable, the CDC stated that it had "confirmed through laboratory testing the first U.S. case of Zika virus infection in a non-traveler in the continental United States. 

"According to a Dallas County Health Department investigation, 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 best way to avoid Zika virus is to avoid mosquito bites and to avoid sexual contact with a person who has Zika virus."

The CDC said it does not have "definitive information" about the time period during which a person is infectious, but recommended the use of condoms to prevent spreading sexually transmitted infections. 

Zika virus usually presents itself as a mild illness, with the most common symptoms of fever, rash, joint pain and conjunctivitis (red eyes). The illness is rarely fatal and usually lasts for about a week. 

“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, the DCHHS director, in a statement.

"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," the agency stated in a press release. 

"There is no specific medication available to treat Zika virus and there is not a vaccine. The best way to avoid Zika virus is to avoid mosquito bites and to avoid sexual contact with a person who has Zika virus."

Public health emergency

On Monday, the World Health Organization (WHO) declared two alarming health outcomes related to Zika as a "public health emergency of international concern." 

These cases include a rare and sometimes fatal birth defect known as microcephaly, which involves babies that are borne with incomplete brain development and smaller than average heads, and Guillain Barré Syndrome, which can cause paralysis in adults. 

Both of these health problems are strongly suspected, although not yet proven to be, caused by Zika virus infections. Microcephaly cases in Brazil alone have soared above 4,000 since October of 2015, compared to the average annual figure of around 250. 

The Zika virus is now spreading through all but one country in Central America and most of South America, as well as territories such as Puerto Rico. 

This Texas case, however, does not signal the arrival of the Zika virus in the U.S. in the way it is spreading throughout other countries, since mosquitoes are the main source for spreading the virus, rather than sexual contact.

The main means of transmission is through mosquito bites from the Aedes aegypti mosquito, which is present in much of North and South America, including in Texas.

The CDC has issued travel advisories warning pregnant women not to travel to countries and territories where active transmission is taking place.