Florida Gov. Rick Scott announced the number of Zika cases likely spread by local mosquitoes had increased to 14 and asked Monday for a federal emergency response team to help the state combat the spread of the virus in the U.S.
The governor also said the Centers for Disease Control and Prevention would issue a travel warning to pregnant women or those thinking of becoming pregnant to avoid a square mile area in Miami-Dade County, where officials believe the active transmissions of Zika are occurring.
Officials announced four cases on Friday, believed to be first people to contract the virus from mosquitoes within the 50 states. The CDC's emergency response team will help Florida officials in their investigation, sample collection and mosquito control efforts. The White House said the CDC team would be deployed to Florida "in short order."
Florida health officials said they've tested more than 200 people in Miami-Dade and Broward Counties after reports of local transmissions of the virus in early July. Of the 14 people infected, two are women and 12 are men.
"We will continue to keep our residents and visitors safe utilizing constant surveillance and aggressive strategies, such as increased mosquito spraying, that have allowed our state to fight similar viruses," Scott said in a statement.
U.S. health officials do not expect widespread outbreaks of the sort seen in Brazil and in Latin America and the Caribbean, in part because of better sanitation, better mosquito control and wider use of window screens and air conditioners.
Although most people who get Zika don't know they're sick, infection during pregnancy can cause babies to be born with small heads and other brain-related birth defects.
The Florida infections are thought to have occurred in a small area just north of downtown Miami, in the Wynwood arts district.
The area, known for murals spray-painted across warehouses, art galleries, restaurants and boutiques, is rapidly gentrifying and has a number of construction sites where standing water can collect and serve as a breeding ground for mosquitoes.
Many walking the streets recently were unaware the virus had spread and confused about how the disease is transmitted.
Jordan Davison and Melissa Felix work for a cruise line and were enjoying their day off Monday looking at the murals in the neighborhood.
"It's not like a big thing right?" said 25-year-old Davidson. "It's kind of freaky -- there's so much going on we didn't know, didn't really think about it ... I might wear bug spray going forward."
More than 1,650 cases of Zika have been reported in U.S. states that were linked either with travel or having sex with a returned traveler, another way the virus can spread.
Bakery owner Mariana Cortez isn't worried that Zika is going to keep locals and tourists from eating her delicious desserts.
"Mosquitoes are not enough of a reason to not come pick up your cake ... I don't think my business is going to be effected by Zika."
On Friday, Florida agricultural officials immediately announced more aggressive mosquito-control efforts, and Florida politicians rushed to assure tourists it's still safe to visit the state.
for details from the Centers for Disease Control and Prevention.
Behind the spread of the Zika virus is a tiny menace that just won't go away.
It's called the Aedes aegypti, a species of mosquito that has played a villainous role in public health history and defeated attempts to wipe it out.
The mosquito is behind the large outbreaks of Zika virus in Latin America and the Caribbean. On Friday, Florida had said four Zika infections in the Miami area were likely the first caused by mosquito bites in the continental U.S. All previous U.S. cases have been linked to outbreak countries.
Five things to know about the bug:
FIRST IN AFRICA
Aedes aegypti is a small, dark, hot weather mosquito with white markings and banded legs. Scientists believe the species originated in Africa, but came to the Americas on slave ships. It's continued to spread through shipping and airplanes. Now it's found through much of the world, including cities across the southern United States.
YELLOW FEVER MOSQUITO
Early in the 20th century, it was the engine behind devastating yellow fever outbreaks and became known as the yellow fever mosquito. Since then, it's also been identified as a carrier for other tropical illnesses such as dengue fever, chikungunya and Zika. Scientists say other types of mosquitoes might also spread Zika but Aedes aegypti is the main culprit. The vast majority of the mosquitoes tested recently in South Florida have been that kind.
A CITY DWELLER
Aedes aegypti has an unusually cozy relationship with people. While other species thrive in more rural areas, or at least in parks and gardens, this is a domesticated species -- sort of a housecat mosquito -- accustomed to living in apartment buildings and city centers. It prefers biting people to animals and likes to feed indoors, during daylight hours. It doesn't venture far. Researchers say it doesn't travel more than a few hundred yards during its lifetime -- usually two to four weeks.
KILLED OFF, IT CAME BACK
The mosquito is a hardy bug that can be particularly challenging to get rid of. In the early 20th century, many countries tried to wipe out the mosquito with chemicals and other measures. By 1970, it was eradicated from much of South America -- including Brazil. But many mosquito-control programs lapsed due to budget problems, concerns about insecticides and the success of the yellow fever vaccine. The species roared back. More recently, scientists have been exploring novel ways of curbing the pest with genetic engineering, radiation or bacterial infections.
GOING FOR BLOOD
Female mosquitoes drink human blood for nutrients used in making eggs. After a female bites an infected person, it can spread the virus through its saliva to its next human victim. While the virus is mostly spread to people through mosquito bites, scientists have established that it's been spread through sex -- mostly by men to their partners -- in some cases. Zika can also be spread through blood; the virus usually stays in the blood for about a week, though it's been seen longer in the blood of pregnant women. A U.S. lab worker was accidentally infected through blood.