A travel advisory has been issued warning pregnant women against visiting an area of Florida where locally transmitted Zika virus has been detected.
The Centers for Disease Control and Prevention wants pregnant women and their partners to avoid a neighborhood of northern Miami where Zika has been spread by mosquitoes, according to the agency's website.
The CDC also warned people who live in or have traveled to the area any time after June 15. This is based on the earliest time that symptoms start and the maximum two-week incubation period for Zika.
On Monday, New York City Health Department Commissioner Dr. Mary Bassett and Deputy Mayor Dr. Herminia Palacio updated the city's travel warning to include Miami. Latin America and the Caribbean had previously been included on the list.
"The fact that Zika is spreading locally in this Miami neighborhood means that pregnant women, women trying to conceive, and their sexual partners put themselves and their unborn child at risk of potential Zika infection when visiting this area," they said in a joint statement.
The warning came less than a week after Gov. Rick Scott announced at a press conference that one Florida woman and three men were believed to have contracted the disease from bites.
As of Monday more than 1,600 Zika cases had been reported in the U.S., excluding territories, but all had originally been contracted abroad by mosquito bites, unprotected sex with someone who had recently traveled out of the country or transmission from mother to child.
At least four New Yorkers have contracted the virus through sex, including a man who may be the first in the world to have caught the disease from his female partner.
New York City also recorded its first case of a baby born with Zika-related birth defects in a local hospital on July 22.
While the symptoms of Zika virus in adults are typically quite mild, infection passed from mother to fetus can cause microcephaly, the symptoms of which include an abnormally small head and stunted mental development.
Here's what you should know about the virus to keep yourself and your family safe:
► What is it?
Zika is a mosquito-borne virus that can spread from an infected pregnant woman to her baby. Both men and women can spread the virus through sexual intercourse.
Symptoms of Zika are "pretty benign" in adults, NYU OB Medical Director and clinical associate professor Dr. William Schweizer said, and include fever, rash, vomiting, joint pain, headaches and conjunctivitis.
Only around "one in five people will exhibit symptoms," which usually last for a few days, Schweizer added.
The mild or nonexistent symptoms are part of the virus's danger, Schweizer said.
"I might have a slight headache, take a Tylenol and continue on with my day... the issue is that [the people who don't exhibit Zika symptoms] might infect other mosquitos, which can then give Zika to someone else," he said.
► Why should pregnant women or women trying to conceive be especially cautious about Zika transmission?
Zika causes birth defects, the city's Health Department warns. It's particularly linked to babies born with smaller-than-normal heads, a condition called microcephaly. Microcephaly has been associated with other problems, such as seizures, developmental delay and intellectual disability.
The Health Department advises pregnant women against traveling to countries with a Zika outbreak during their pregnancy. For those who have returned from travel abroad, it recommends testing for the virus, and for those having sex with a partner who may have Zika, it recommends the use of condoms or other barrier protection.
For women and men who have traveled to a Zika-affected area and are trying to conceive, the Health Department advises waiting at least eight weeks after any possible infection, with or without symptoms. Men who do test positive for Zika and/or display symptoms should use protection during sex for at least six months after returning home from abroad.
► Which where should pregnant women try to avoid for the time being?
According to the Centers for Disease Control and Prevention, the Zika outbreak began last May in Brazil. It has since traveled throughout Central America, South America, the Pacific Islands and the Caribbean. On Monday Miami, Florida, was added to that list.
The first baby born in the U.S. with Zika virus was reported in Hawaii the week of Jan. 11, after the mother had spent time in Brazil.
The CDC lists these countries and territories where Zika transmission is ongoing and warn that it will continue to spread.
"Even though the risk on an individual basis might not be tremendously high, the consequences are serious," said Columbia University virologist and professor of epidemiology Dr. Stephen Morse. "We don't have vaccine for [Zika]... if a newborn has it, there's not a chance for normal brain development
Said Morse, "If a [pregnant woman] doesn't have to go, I would wait."
If you do decide to travel to the countries where the Zika virus is confirmed, Morse and Schweizer recommend taking precautions such as using mosquito nets, staying in hotels that have screens and air conditioning and wearing DEET repellent. When you return, do what you can to keep mosquitos from biting you for three weeks, to avoid spreading the virus locally.
► How likely is the virus to spread beyond Florida?
In the Caribbean and in Latin and South America, the virus is carried by the yellow fever mosquito, a species found in urban areas of South Florida. Aedes aegypti mosquitoes are believed to be the vector for the four locally transmitted cases in Miami-Dade county. Their population appears to be limited to the southeastern United States, although the related Asian tiger mosquito, an invasive species far more common through the country, could also potentially carry the virus.
The CDC advises the public to use insect repellent, wear long-sleeved shirts and long pants, repair window and door screens, use air conditioning whenever possible and remove standing water that serves as a breeding ground for mosquitoes.