Ten New Local Zika Cases in Florida Prompt Travel Warning


August 01, 2016

UPDATED August 1, 2016 // Florida Governor Rick Scott today said that 10 more individuals in the Miami area have been infected with Zika, likely through mosquito bites, which has quickly brought the total to 14 since the first four cases were announced on July 29.

Florida is the first state to report local transmission of the virus, which causes birth defects, most notably, microcephaly.

In a sign of a rapidly developing outbreak, the Centers for Disease Control and Prevention (CDC) has issued a travel advisory cautioning women who are pregnant to avoid unnecessary travel to the one-square-mile neighborhood just north of downtown Miami that is experiencing local Zika transmission. If any pregnant women have visited this area since June 15, they should be tested for the virus. And if women and men considering pregnancy choose to visit it, they should wait 8 weeks after they return home to attempt to conceive.

Furthermore, pregnant women and their partners living in the Miami neighborhood should take precautions against mosquito bites and sexual transmission of the virus.

Six of the 10 newly identified individuals who contracted the virus from mosquitos were asymptomatic. The Florida Department of Health (DOH) identified them through a door-to-door survey of its Zika zone.

In a news conference today, CDC Director Tom Frieden, MD, MPH, said there is no evidence yet of widespread virus transmission, "but there could be sustained transmission in small areas."

Otherwise, "Florida remains safe and open for tourism," Scott said in a news release. Dr Frieden said in a news conference on July 29 that the outbreak in southern Florida was not yet extensive enough to warrant a travel advisory. The decision to issue one 3 days later, Dr Frieden said today, reflects not only the identification of 10 more cases of local virus transmission but also a die-hard population of the Zika-carrying Aedes aegypti mosquito despite heavy spraying of insecticide.

Why the Aedes aegypti mosquitos defy eradication efforts remains unclear, said Dr Frieden. They may be resistant to the insecticides in use, or else they are hatching in "cryptic" places that spraying cannot reach. And these mosquitos have proven difficult to quell in the past.

Why Just One Neighorhood?

Dr Frieden defended limiting the travel advisory to the small neighborhood north of downtown Miami instead of extending it to the entire metro area. The Florida DOH has investigated other neighborhoods, he said, but failed to find evidence of local transmission. Furthermore, the Aedes aegypti mosquito doesn't travel more than 150 meters in its lifetime. The area defined in the advisory goes far beyond that.

And unlike West Nile virus, which can be harbored long term by birds, the Zika virus is spread by mosquitos only as long as they are getting infected or reinfected by the humans they bite, Dr Frieden explained. "It persists where there is a crowded population without access to air-conditioning or [window] screens and the presence of a large number of mosquitos.

"We will continue to look at these data every single day, including additional testing, and if that changes, we'll adjust the area of warning," he said.

Public health authorities in the United Kingdom beat the CDC to the punch on a travel advisory. An agency called Public Health England earlier added "affected areas" in Florida to its list of countries and regions that pregnant women should avoid visiting, characterizing the risk for Zika infection there as moderate.

In a news release, Florida's governor emphasized his state's successful track record in managing mosquito-borne diseases. "While I encourage all residents and visitors to continue to use precautions by draining standing water and wearing bug spray, Florida remains safe and open for tourism," Scott said. "This year, we have already welcomed a record 30 million tourists, and we look forward to welcoming more visitors to Florida this summer."

CDC Emergency Response Team Activated

At Scott's request, the CDC has activated an eight-member CDC Emergency Response Team (CERT) to help the state investigate the outbreak, collect Zika virus samples, and control mosquitos. The state has been criticized for not requesting a CERT sooner, after suspicion arose that some infections had not resulted from travel to a country where the virus is spreading locally or from sex with such a traveler.

Dr Frieden said two CERT members are already in Florida and that the rest are scheduled to arrive today and tomorrow. The team includes experts on the Zika virus, pregnancy, birth defects, vector control, laboratory science, and risk communications.

"We're doing all that science can allow and working around the clock to prevent infections," he said.

More information about the CDC's response to the Florida outbreak is available on the agency's website.


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