All of the women contracted the mosquito-borne virus while traveling abroad, Dallas Health and Human Services officials told CBS News.

In related news, the U.S. House on Thursday approved a $1.1 billion funding package to combat the Zika threat.


The bill still needs to be approved by the U.S. Senate, and it remains to be seen if President Barack Obama will sign it. Obama originally asked Congress for $1.9 billion, and Democrats and the White House have voiced opposition to certain provisions of the package.

Even though there have been no local transmissions of Zika reported yet in the United States, the number of cases of infection among pregnant women keeps climbing.

As of June 9, the U.S. Centers for Disease Control and Prevention reported there are 234 cases of pregnant women on the U.S. mainland who have been infected with Zika, which typically involves relatively mild symptoms in most adults. However, it can cause devastating birth defects in babies that include microcephaly, where an infant is born with an abnormally small head and brain.

In Latin America, thousands of babies have already been born with microcephaly. And researchers reported Wednesday that fears over Zika-related birth defects may be driving up abortion rates in Latin American countries affected by the virus.

In Brazil and Ecuador -- where governments have issued health warnings on the danger to the fetus from maternal Zika infection -- requests for abortion in 2016 have doubled from 2010 rates, the researchers reported.

The other 17 Latin American countries covered by the new study had their rates rise by more than a third during that time, according to the report in the New England Journal of Medicine.

The researchers noted that because data on family planning in Latin America is often hard to come by, their numbers may underestimate the surge in abortions since Zika's emergence.

"The World Health Organization predicts as many as 4 million Zika cases across the Americas over the next year, and the virus will inevitably spread to other countries," noted study senior author Dr. Catherine Aiken, of the University of Cambridge in England.

But no nation has been more affected than Brazil. As a result of the Zika epidemic, almost 5,000 babies have been born with microcephaly there.

However, the CDC warned last Friday that infection rates are rising in Puerto Rico. Testing of blood donations in the U.S. territory -- "our most accurate real-time leading indicator of Zika activity" -- suggest that more and more people on the island have been infected, according to CDC Director Dr. Tom Frieden.

"The real importance of this information is that in coming months it's possible that thousands of pregnant women in Puerto Rico could become infected with Zika," Frieden stressed. "This could lead to dozens or hundreds of infants being born with microcephaly in the coming year," he added.

RELATED CDC reports six cases of birth defects caused by Zika

"Controlling this mosquito is very difficult," Frieden said. "It takes an entire community working together to protect a pregnant woman."

Because the virus remains largely undetected, it will be months before affected babies begin to be born, Frieden said. Some will have microcephaly or other brain-related birth defects. But many will appear healthy and normal, and there's no way to know how they might have been affected, he explained.

Zika is typically transmitted via the bite of the Aedes aegypti mosquito. But, transmission of the virus through sex is more common than previously thought, World Health Organization officials have said.

Women of child-bearing age who live in an active Zika region should protect themselves from mosquitoes by wearing long-sleeved shirts and long pants, using mosquito repellent when outside, and staying indoors as much as possible, according to the CDC.

More information

Visit the U.S. Centers for Disease Control and Prevention for more on the Zika virus.

This Q&A will tell you what you need to know about Zika.

To see the CDC list of sites where Zika virus is active and may pose a threat to pregnant women, click here.

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