4 Zika Cases in Florida Were Likely Spread by Local Mosquitoes
Four cases of Zika infection in Florida are very likely to have been caused by mosquitoes there, the State Department of Health said Friday — the first documented instances of local transmission in the continental United States.
“Zika is now here,” Dr. Thomas R. Frieden, the director of the Centers for Disease Control and Prevention, said at a news briefing.
The C.D.C. and Florida officials said that for now, the area of concern is limited to one square mile in the Wynwood neighborhood of Miami, a gentrifying area with restaurants and art galleries just north of downtown.
Health authorities are not advising people to stay away from the neighborhood, Dr. Frieden said. The four people appear to have been infected in early July; since then, mosquito control efforts have been stepped up in the area, and additional cases have not been identified.
We don't currently see a situation where we would advise people not to travel there or advise pregnant women not to travel there, Dr. Frieden said. But he said that this advice could change if the number of cases increased substantially.
We would not be surprised if individual additional cases are reported,” he said. And because Zika infection often does not produce any symptoms, there may be more cases than we know of now.
The Florida cases signal a new stage in an epidemic that has left a trail of birth defects in Brazil and strained health care resources throughout Latin America. The epidemic is raging in Puerto Rico, C.D.C. officials reported last week: Two percent of blood donors there have been recently infected, and hundreds of pregnant women have tested positive.
Researchers had long predicted that the Zika virus would gain a toehold in the continental United States, most likely in Florida and along the Gulf Coast. While the outbreak is not expected to escalate sharply, its course is uncertain.
There are now more than 1,600 confirmed Zika cases in the continental United States. Until the announcement on Friday, all of them had been a result of travel abroad: The virus was contracted either by a mosquito bite elsewhere or by intercourse with someone who had been to a Zika-affected area.
None of the four patients in Miami had traveled to Zika-affected areas in Latin America or the Caribbean. After interviewing more than 200 people, Florida health authorities have apparently concluded that none were infected through other means.
Dr. Frieden said that the one woman and three men, residents of Miami-Dade and Broward Counties, were not related, but that all had been in a section of Wynwood around the time they were infected in early July.
At least two were working at different sites in the neighborhood, which had “conditions that can spread Zika,” such as standing water that can attract mosquitoes.
Officials declined to say if the infected woman was pregnant. Zika infection is mild for most people, but in a developing fetus, it can cause a condition called microcephaly, characterized by abnormally small heads and brain damage. In rare cases in adults, it can also cause a form of temporary paralysis.
Gov. Rick Scott said in a statement that none of the four “exhibited symptoms to be admitted to the hospital.”
No mosquitoes tested in Florida have been found carrying the Zika virus, but Dr. Frieden said that was not surprising. “Confirming mosquito-borne transmission is not as easy as confirming infection,” he said.
Although the Aedes aegypti mosquito, which transmits the Zika virus, cannot travel far — its range is a maximum of 150 meters or a little under 500 feet — finding individual mosquitoes carrying the virus would be a rare stroke of investigative luck, he said.
Since the cases were identified, health workers have been going door to door in the neighborhood collecting urine samples for testing of residents. The Food and Drug Administration this week halted blood donations in South Florida until they can be screened for Zika infection.
If Florida mosquitoes were infected, health officials said, it is likely to be because they bit someone in Florida who had traveled to Latin America and been infected by a Zika-carrying mosquito bite there.
Two prominent public health experts had sharply different opinions about the C.D.C’s decision against advising pregnant women to avoid travel to the area.
Dr. William Schaffner, head of preventive medicine at Vanderbilt University medical school, said the decision was rational. “Two weeks give you a comfort zone,” he said. “If the sense is that the problem has been taken care of and the hazard has been reduced to background level again, then, in the absence of further transmission, I think that’s reasonable.”
But Dr. Peter J. Hotez, dean of the National School of Tropical Medicine at the Baylor College of Medicine in Houston, said he thought the C.D.C. was wrong to treat a cluster of Zika cases as if it were a cluster of dengue or chikungunya, two related viruses carried by the same breed of mosquito.
“This virus doesn’t play by the same rules,” he said. “I think they should tell them: If you’re pregnant or planning to be, don’t travel to the Miami area unless you have to. If you’re in the area, delay getting pregnant during the period when arbovirus transmission peaks, which is the end of July to the beginning of September. And then we’ll see what happens.”
The Wynwood area contains a mix of warehouses, restaurants, bars, galleries, and its housing ranging from low-income apartments to tony high-rises. The area has a large population of people from the Dominican Republic and Puerto Rico, where Zika cases have been proliferating in recent weeks.
The neighborhood that the authorities are focusing on is bound by Northwest Fifth Avenue, U.S. Route 1, Northwest/Northeast 38th Street and Northwest/Northeast 20th Street.
At first glance, the bustling crowds in Wynwood betrayed no sense of unease on Friday afternoon. But it was there.
SOURCE: The Nwe York Time & Florida Department of Health.