Avoiding the mosquito-borne Zika virus just got more complicated.

A case of Zika contracted through sexual transmission was confirmed Tuesday by the U.S. Centers for Disease Control (CDC) in Dallas County, Texas. The patient, who had not traveled to a Zika-impacted country, became infected after having sexual contact with an infected person who had returned from Venezuela, where Zika is present.

Until Tuesday, health experts had suspected but never confirmed that the mosquito-borne virus could spread through human-to-human contact. The report came one day after the World Health Organization (WHO) designated Zika a global emergency.

"If a traveler contracts the virus while traveling, under most plans they would be covered for emergency medical, medical evacuation and trip interruption benefits."

Amid these alarm bells, many American travelers are wondering whether they should cancel trips to countries affected by the outbreak, which include Mexico and much of Central America, South America and the Caribbean. At least 19 cases of Zika have also been reported in Puerto Rico.

Most travel groups say it’s too early to tell if the epidemic will have an impact on bookings, but some travel agents say they’ve received a number of cancellations – many of those for trips to Mexico. And some travel insurance companies are reporting a surge in sales of “cancel for any reason” policies, Reuters reported.

“Most insurance plans are treating the Zika as any other illness in the respective plan's terms and conditions,” said Stan Sandberg, co-founder of Travelinsurance.com. For example, if a traveler contracts the virus while traveling, under most plans they would be covered for emergency medical, medical evacuation and trip interruption benefits.

Only a minority of Zika patients show symptoms, most of them relatively minor: low-grade fever, body aches, headache, red eyes and a body rash. More rarely, there may be abdominal pain, nausea, and diarrhea. Symptoms usually appear two to 12 days after a mosquito bite and go away within a week. Patients rarely require hospitalization.

“Eighty percent of people who are infected will have no idea at all that they have the virus,” said Dr. Christina Leonard Fahlsing, an infectious disease specialist at Spectrum Health, a not-for-profit health system based in West Michigan.

“Once in your system, the virus actually clears your blood after seven days,” Fahlsing said. “You develop immunity so that you can’t ever get re-infected.”

But some Zika patients have contracted Guillain-Barré syndrome, a rare and sometimes deadly neurological condition in which the immune system damages nerve cells, leading to muscle weakness and even paralysis.

Even worse, Zika has been linked to a birth defect called microcephaly, which causes the brain to develop abnormally in the womb. Children born with the condition have unusually small heads and will have developmental and intellectual disabilities throughout their lives.

Since the virus has been linked to microcephaly in babies whose mothers were infected during pregnancy, the CDC recommends that pregnant women postpone travel to countries affected by the outbreak.

The report that the virus can be transmitted sexually puts others in the risk category. “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, director of Dallas County Health and Human Services (DCHHS).

But unless you are pregnant, this doesn’t mean you should cancel your vacation or business trip. If you travel to the affected areas, you can greatly reduce the risk of getting infected by taking standard mosquito precautions, Fahlsing said.

These include staying in accommodations with air conditioning and screened windows, using mosquito repellant and wearing long sleeves and long pants. Look for repellents that include the ingredient DEET and apply them to skin and clothing.

“Also, the Zika-carrying mosquito is a day feeder, so be sure to use bug spray during daytime hours,” Fahlsing said.

If you’re planning a romantic getaway, you should practice safe sex while there – and for a week after returning home. “Next to abstinence, condoms are the best prevention method against any sexually transmitted infections,” Thompson said.

If you’re still too worried to travel, major airlines are providing some flexibility, though policies differ. United, JetBlue and Virgin America are allowing passengers booked on flights to countries affected by the Zika outbreak to rebook or receive refunds. American Airlines is limiting its offer to pregnant women who can provide a doctor’s note.

Most cruise lines are allowing pregnant women booked on ships that visit outbreak zones to postpone their cruise or choose another itinerary.