MIAMI — Three weeks after local Zika cases emerged in Miami's Wynwood neighborhood, the mosquito-borne virus marched into Miami Beach, with five local cases that signaled the infectious disease won't easily be defeated.
The news, announced Friday by Florida Gov. Rick Scott during a hasty trip to Miami, led to an unprecedented advisory by federal health officials who told pregnant women to avoid the tourist destination — and consider postponing travel to Miami-Dade County altogether.
"If you're concerned about Zika," CDC director Tom Frieden said, "you may consider postponing all non-essential travel to all parts of Miami-Dade County."
Scott identified a 1.5-square-mile zone of Miami Beach as the second area in Miami-Dade where mosquitoes are spreading Zika. The first transmission zone, identified on July 29, is a 1-square-mile area in the Wynwood neighborhood of Miami.
In a region synonymous with the glamor and nightlife of South Beach, where exposed skin is de rigueur and an outdoor lifestyle is a year-round attraction, Zika is an unwelcome visitor. Tourism boosters and state leaders may be accustomed to dealing with hurricanes and other natural disasters but a public health crisis is something different.
State Surgeon General Celeste Philip, whose health department has led the response to Zika, appealed to a sense of community as she urged Floridians to take responsibility for stopping the spread of a disease that can cause severe birth defects and neurological disorders.
"In times like this, we really see that our strength within our state lies in our ability to support each other and come together," she said. "We all have a responsibility to protect pregnant women."
She ran down the increasingly familiar litany of recommendations: use insect repellent outdoors, wear long sleeves and pants, and drain containers of standing water so they don't become mosquito breeding grounds.
The Centers for Disease Control and Prevention, along with the state health department, specifically warned pregnant women to avoid the area of Miami Beach between Eighth and 28th streets from Biscayne Bay to the Atlantic Ocean. That's in addition to the previously identified 1-square-mile zone in Miami's Wynwood neighborhood.
Five people have contracted the disease from mosquitoes in Miami Beach over the past several weeks, including two Miami-Dade residents and tourists from New York, Texas and Taiwan.
Pregnant women who have visited the identified area of Miami Beach since July 14 were advised to consult with their doctor and consider being tested for Zika, which the state department of health is offering for free to all expectant mothers in Florida.
With mosquitoes now spreading the virus across Biscayne Bay from Wynwood, the fight to contain the Aedes aegypti species most capable of transmitting the disease will be much more challenging.
Miami Beach has a larger population than Wynwood, making the disease's spread more likely. But the environment also presents obstacles for reducing mosquito populations.
Aerial spraying cannot be conducted amid the high-rise buildings and sea breezes of Miami Beach, Frieden said, because the airplanes fly low, about 100 feet above the ground, and the pesticide mists likely will be blown off target.
"The inability to use aerial spraying there means we will be restricted to ground-based technologies, like backpack spraying," he said.
Crowds of tourists on Miami Beach, and an abundance of people in bathing suits and little clothing, also means more infections are likely. "Zika spreads by the movement of people," Frieden said.
The CDC has an Emergency Response Team in Miami working with the Florida Department of Health to investigate local cases of Zika, Frieden noted. And he noted that a combination of aerial spraying and backpack fogging in Wynwood has been effective.
"We're seeing more than 90 percent of mosquitoes in traps killed during each event," he said.
But while Scott says the state has "cleared" sections of the square-mile area in Wynwood, the CDC's guidance advising pregnant women to avoid the entire zone has remained unchanged.
In Miami Beach early Friday, an army of public workers fanned out across the affected area in search of mosquito breeding grounds to stamp out, even before the announcement from the governor that Zika was spreading.
"We're cleaning to make sure there's no standing water or litter that could be a place for mosquitoes," said Juan Rosario, superintendent of sanitation.
City workers swept the streets with pressure cleaners, pushing pools of standing water into gutters using 250-degree blasts to kill any living thing in it. Sanitation trucks with vacuums sucked up debris. And inspectors sprinkled larvicide pellets into storm drains to kill eggs.
Code compliance officers issued at least one citation Friday morning, after they spotted someone pushing water out the back of a business into the alley, where it pooled in a groove in the pavement.
Florida's aggressive response to containing Zika's spread won praise from Frieden, who noted the state's history with other mosquito-borne illnesses, such as dengue and chikungunya.
But Scott, speaking at the Miami-Dade Department of Health, did not reciprocate. Instead, he criticized federal officials for being slow to respond to his repeated requests for additional resources, such as Zika testing kits and prevention supplies for pregnant women.
Scott said the health department has tested more than 6,673 people statewide for Zika virus, and that Florida currently has the capacity to test nearly 5,000 people for active Zika and almost 2,800 people for Zika antibodies.
But he called on the CDC to send more supplies, including an additional 5,000 Zika antibody test kits to ensure rapid testing, additional lab support and personnel, and 10,000 Zika prevention kits for pregnant women.
"I have repeatedly called on the federal government for these kits," Scott said, "and as of today we have not received additional resources for them."
Frieden said the CDC already has sent Florida 10,000 cans of mosquito repellent, which is included in a Zika prevention kit along with bed netting and other materials. He said the federal agency also has sent Florida $35 million to purchase any Zika prevention and preparedness supplies the state may need.
Frieden said the CDC received the governor's request for additional kits after Scott's morning press conference and that the federal agency had already arranged to ship the supplies by Tuesday.