MONDAY, Sept. 19, 2016 (HealthDay News) -- U.S. health officials on Monday lifted the Zika virus travel advisory that urged pregnant women to avoid travel to Miami's Wynwood neighborhood.

The Centers for Disease Control and Prevention continues to ask pregnant women and their partners to take precautions to prevent mosquito bites if they travel to or live in Wynwood. An arts district north of downtown Miami, Wynwood became the first area in the continental United States with mosquito transmissions of the virus that can cause terrible birth defects.

But vigorous mosquito-control efforts appear to have paid off in Wynwood, halting new cases of Zika virus transmission in that area, CDC Director Dr. Tom Frieden said Monday.

"We've reached this point because of the tremendous progress with mosquito control in the affected area, including the combination of aerial application of the larvicide Bti and the adulticide Naled, and rigorous investigation of possible Zika infections by Florida health officials," Frieden said in a news release.

Still, Zika remains a threat in the Miami-Dade County area, health officials said. The mosquito season in southern Florida continues through the fall, as does the risk of new local Zika outbreaks.

A second Zika virus transmission zone centered in Miami Beach has tripled in size, Florida Gov. Rick Scott announced late last week.

The Miami Beach zone now includes a 4.5-square-mile zone -- up considerably from the originally designated 1.5-square-mile zone, Florida Department of Health officials said.

Health officials enlarged the zone after they identified five people -- two men and three women -- in the larger area who all had experienced Zika symptoms within one month of each other, according to a CNN report.

Zika is the first mosquito-borne virus known to cause severe birth defects, most of them brain-related. The most common one is microcephaly, in which a child is born with an abnormally small brain and skull.

As of Sept. 14, a total of 3,176 cases of Zika had been reported in the United States, the CDC said.

These cases included: 43 locally transmitted mosquito-borne cases in Florida, 26 cases believed to be the result of sexual transmission, and one case that was the result of laboratory exposure, the agency said.

There have been no cases of microcephaly in the continental United States caused by local transmission of the Zika virus by mosquitoes. The current Zika epidemic began in Latin America, with Brazil reporting thousands of microcephaly cases.

In its announcement regarding Wynwood, the CDC continued to urge pregnant women and their partners to postpone nonessential travel to all parts of Miami-Dade County if they're concerned about potential Zika exposure.

"We encourage people not to let down their guard. We could see additional cases," Frieden said. "People living in or visiting Miami-Dade County, particularly pregnant women, are encouraged to continue to take steps to prevent mosquito bites and to follow guidelines for preventing sexual transmission."

The CDC first announced its Wynwood travel advisory in early August, based on evidence that mosquitoes had been actively transmitting Zika from person to person.

No new cases of locally transmitted Zika have been reported in the Wynwood zone since early August, and low numbers of mosquitoes have been found in traps there for the past several weeks since aerial application of pesticides, the CDC said.

The CDC's Interim Zika Response Plan requires that three mosquito incubation periods -- about 45 days -- should pass without any new cases before the agency considers updating a travel advisory.

More information

The U.S. Centers for Disease Control and Prevention provides more information on mosquito-borne diseases.

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.