Health officials advised pregnant women to avoid a part of Miami where mosquitoes are transmitting Zika directly to humans.
Mosquitoes have apparently started spreading Zika on the U.S. mainland, citing four cases they strongly believe were caused by bites.
Ten more cases were announced Monday, even though Florida authorities have yet to find any mosquitoes actually carrying the virus.
Of the 14 people infected, two are women and 12 are men.
Eight patients showed symptoms of Zika, which can include fever, rash, joint pain and red eyes. The others had no symptoms. The disease is often so mild that most people don't know they are infected.
WHAT YOU NEED TO KNOW ABOUT ZIKA
WHAT IS ZIKA?
The Zika (ZEE'-ka) virus was first discovered in monkey in Uganda in 1947 - its name comes from the Zika forest where it was first discovered.
It is native mainly to tropical Africa, with outbreaks in Southeast Asia and the Pacific Islands.
It appeared in Brazil in 2014 and has since been reported in many Latin American countries and Caribbean islands.
HOW IS IT SPREAD?
The World Health Organization says Zika is rapidly spreading in the Americas because it is new to the region.
People aren't immune to it, and the Aedes mosquito that carries it is just about everywhere - including along the southern United States.
Canada and Chile are the only places without this mosquito.
It is typically transmitted through bites from the Aedes species of mosquitoes.
They are aggressive feeders, commonly biting multiple people in quick succession, fueling the spread of the virus.
The Aedes aegypti - which spreads other tropical diseases like dengue fever, chikungunya and yellow fever - is most commonly associated with Zika. It thrives in warm climates.
Its cousin, the Aedes albopictus has also been linked to Zika. Worryingly for Americans in northern states, this species can survive in cooler temperatures.
Unlike some other types of mosquito's, Aedes mosquitos are active during the daytime.
They are most active during mid-morning and then again between late afternoon and nightfall.
Scientists have found Zika can be transmitted sexually - from both men and women.
Couples should abstain or wear condoms for eight weeks if either partner has traveled to a country with a Zika outbreak, regardless of whether they have symptoms.
The first case of sexually-transmitted Zika during the current outbreak was reported in Texas at the beginning of February.
The woman became infected after sexual contact with a man who had caught the virus in another country.
On July 15, it was confirmed that women can pass the virus to men after such a case was seen in New York City.
There are also reported cases of sexual transmission in France and Canada.
Prior to this outbreak, there was a case of sexual transmission of Zika in 2008 when researcher from Colorado, who caught the virus overseas, infected his wife on returning home.
MOTHER TO BABY
A mother can pass the virus to her unborn baby during pregnancy.
There are two ways this can happen, according to a recent study.
Through the placenta: During the first trimester, it can travel through the placenta by infecting numerous placental cells - something very few viruses can do.
This route is the most damaging to the fetus, and is most likely to leave the child with birth defects, including microcephaly.
Through the amniotic sac: In the second and third trimester, the virus can make its way through the amniotic sac.
This route is less likely. The baby would have a much smaller risk of birth defects at this stage than if it were infected in the first trimester.
During childbirth: Since the virus can live in the woman's womb lining, there is a chance the baby can become infected when it is born.
ARE THERE SYMPTOMS?
The majority of people infected with Zika virus will not experience symptoms.
Those that do, usually develop mild symptoms - fever, rash, joint pain, and red eyes - which usually last no more than a week.
There is no specific treatment for the virus and there is currently no vaccine to protect against infection, though several are in the developmental stages.
CAN THE SPREAD BE STOPPED?
Individuals can protect themselves from mosquito bites by using insect repellents, and wearing long sleeves and long pants - especially during daylight, when the mosquitoes tend to be most active, health officials say.
Eliminating breeding spots and controlling mosquito populations can help prevent the spread of the virus.