Zika Virus Leads to Unprecedented CDC Florida Travel Warning

The Centers for Disease Control and Prevention issued an historic warning on Monday, advising pregnant women and their partners to avoid a small community just north of downtown Miami. Agency spokesman Tom Skinner says this is the first time the CDC has warned people not to travel to an American neighborhood for fear of catching an infectious disease.

Zika virus infection during pregnancy can cause of microcephaly, a condition where a baby's head is much smaller than expected due to an underdeveloped brain. The condition can cause developmental delays, intellectual disabilities, problems with movement and balance, difficulty eating and swallowing, vision and hearing loss, or death.

14 people in Florida have now been infected with Zika virus after being bitten by local mosquitoes.

Florida Gov. Rick Scott and CDC Director Dr. Tom Frieden announced the warning in separate news conferences Monday. 10 new cases of infection were found by door-to-door surveys of 200 people in their homes and businesses, after being tested by urine and blood samples for the virus or an antibody.

Last week Florida state health officials confirmed that four people had contracted Zika from mosquitoes, all in the same 150-square- meter area. It's a mixed-use development with both upscale and lower income businesses and homes.

Frieden said this mixed neighborhood composition complicates mosquito control efforts.

"New test measurements over the weekend showed a risk of continued active transmission in that area," he said. "Because of this finding, we are advising pregnant women not to travel to that area and if they have traveled there on or after June 15 to visit their health care provider for testing."

Local health officials believe that June 15 is the earliest date that the mosquitoes might have passed the virus, which they obtained by biting a person who had returned to the United States with the disease. Four out of five people with Zika have no symptoms, so it's possible that "person zero" had no idea they were infectious.

"With 40 million travelers to and from areas where Zika is actively circulating, many can come back who feel perfectly fine," Frieden said. "But the virus could be hitchhiking in their blood."

Everyone who travels to one of those areas is asked to consistently use insect repellent for at least three weeks after they return.

Additional precautions recommended by the CDC about the Miami outbreak include:

• Pregnant women who live in or travel to the area should be tested for Zika infection in the first and second trimesters of pregnancy, even if they have no symptoms of the virus.

• Pregnant women and their male and female partners who live in the area should take steps to prevent mosquito bits and use proper sexual protection for the length of the pregnancy, or abstain from sex altogether.

• Male or female partners of pregnant women who have traveled to this area should use safe sex measures for the rest of the pregnancy.

• Women and men who have traveled to the affected area should wait eight weeks to conceive after their return. Men with symptoms should wait a full six months.

Governor Scott was quick in asking for CDC assistance.

"Following today's announcement, I have requested that the Centers for Disease Control activate their emergency response team to assist (the Department of Health) in their investigation, research and sample collection efforts," Scott said. "Their team will consist of public health experts whose role is to augment our response efforts to confirmed local transmissions of the Zika virus."

Some CDC personnel are already on the ground, with more arriving over the next few days.

Their first task will be to understand why local mosquito control efforts failed. Aggressive mosquito control in the area has had limited results. Friedan suggested the local mosquitoes may be resistant to the pesticide being used, or maybe there are hidden spaces where small amounts of water accumulate, just enough for the insects to breed.

"The Aedes aegypti is a really tough mosquito to control," Frieden added. "When Key West had an outbreak of dengue, which is carried by the same mosquito, that outbreak continued for more than a year. It's a demonstration of how intensive the efforts need to be to control the mosquito."

On-the-ground testing could take several weeks, and precautions should continue to be taken by everyone living in the area or traveling to and from it. People are advised to wear long-sleeved shirts and long pants that are thick enough to repel mosquito bites, use air conditioning and screens on doors, remove any standing water where mosquitoes could lay eggs, and apply insect repellent containing 25% DEET to all uncovered skin.

Some local transmission of the virus is expected from mosquitoes but it should not be as widespread as it has been in other parts of the world. That assessment is based on past outbreaks of two similar mosquito-borne diseases, dengue fever and chikungunya, in the United States. The diseases did not spread as rapidly when living conditions included more mosquito-control efforts and the regular use of air-conditioning.

Most of the cases of Zika in the United States have been from travel to one of the 60 countries and territories where the virus is actively circulating. Fifteen people have been infected by sexual transmission, and there is one case of a laboratory-acquired infection.

Only four states, Idaho, South Dakota, Wyoming and Alaska have not yet reported any cases. Until the announcement Friday in Florida, no US cases are believed to have been from local mosquito transmission.