Liz Szabo and Liz Freeman

USA TODAY NETWORK

MIAMI BEACH, Fla. — Pregnant women should now avoid a popular section of this tourist district where Zika is spreading, in addition to a smaller area north of downtown Miami, the Centers for Disease Control and Prevention announced Friday.

Pregnant women and their sexual partners who are concerned about the virus could also consider avoiding "nonessential travel" to all of Miami-Dade County, according to the CDC. Although Zika mostly spreads through mosquito bites, both men and women can transmit the virus sexually.

Florida health officials, who have been grappling with a Zika outbreak in Miami's Wynwood neighborhood, confirmed Friday that five people also have been infected in South Beach, the vibrant community that's located across Biscayne Bay from the rest of Miami and known for its pastel-colored buildings and art deco architecture.

The new cases bring the total number of infections spread by local mosquitoes to 36, Gov. Rick Scott said. The five latest patients were infected within a 1.5 square mile area of Miami Beach, said Scott, whose state is the first to experience a Zika outbreak from native mosquitoes. The bulk of the USA's more than 2,200 cases of the virus are related to travel.

The affected area of Miami Beach stretches from the beach to the Intracoastal Waterway, from 8th Street to 28th Street, Scott said.

People who live in or who have traveled to this area since July 14 should be "aware of active Zika virus transmission," the CDC said. Pregnant women who have been to this area since that date should see their doctor or other healthcare provider about getting tested for Zika. Men and women with a pregnant sex partner who have visited the area since July 14 "should consistently and correctly use condoms to prevent infection during sex or avoid having sex for the duration of the pregnancy."

The CDC recommends all pregnant women be assessed for possible exposure to Zika virus, although not all of them need to be tested. Testing for Zika is time-consuming and the number of lab staff available to perform the tests is limited.

Mosquitoes could be spreading the virus in other areas in Miami-Dade County that haven't yet been recognized, said CDC Director Thomas Frieden. "There are undoubtedly more infections that we’re not aware of right now," he said.

Frieden notes that 80% of Zika patients have no symptoms, making the disease difficult to diagnose. Patients can incubate the virus for up to two weeks before showing signs of the disease, which can include fever, rash, joint pain, pink eye, headache and other problems.

The CDC took the unprecedented step earlier this month to warn pregnant women to avoid the Wynwood neighborhood that's located north of downtown. The area of concern in Wynwood has since shrunk as officials investigated the outbreak.

What you need to know about Zika and pregnancy

Pregnant women are at greater risk than others from Zika because the virus can cause devastating birth defects in fetuses, including serious brain damage. "I ask every Floridian to take proper precautions," Scott said.

"We all have to do our part to wear bug spray and dump standing water," where mosquitoes can breed, he added. "If you see standing water, no mater how small, dump it."

The new Miami Beach cases include two people from Miami Beach, one from New York, one from Texas and one from Taiwan.

Florida "will do everything we can to help pregnant women all across our state. We have a safe state and we are going to keep it that way," Scott said.

Scott, who has requested additional help from the CDC to deal with the outbreak, said officials are taking aggressive mosquito-control measures.

The large number of high-rise buildings in Miami Beach makes it difficult to kill mosquitoes by spraying from the air, Frieden said. That's because the airplanes that spray pesticide tend to fly at altitudes of only about 100 feet. Mosquito-control workers will likely have to spray pesticides by hand, using "backpack" pesticide containers. The pesticides used in Wynwood appear to kill about 90% of mosquitoes hit with the spray.

Controlling Zika mosquitoes may be 'lost cause'

"We're just impressed by the resilience of this mosquito," Frieden said. "It's a tough mosquito to spray."

Scott has asked the CDC for an additional 5,000 Zika antibody test kits "to ensure we can quickly test people for the virus and additional lab support personnel to help us expedite Zika testing," he said. He has also asked the Obama administration for an additional 10,000 Zika prevention kits. Scott said he's waiting for a "detailed plan" on how to work with FEMA.

At least 529 pregnant women in the continental U.S. and Hawaii have been infected with Zika, according to the CDC. Seventeen American women have given birth to babies with Zika-related birth defects and six have lost pregnancies due to the disease, according to the CDC.

More than 13,000 people have been diagnosed with Zika in Puerto Rico, including at least 1,106 pregnant women, according to the Puerto Rico health department. About 100 Puerto Ricans with Zika have been hospitalized and two have died.

Szabo reported from McLean, Va., for USA TODAY. Freeman reports for the Naples (Fla.) Daily News.