Earlier this week federal health officials urged pregnant women to stay away from a Miami neighborhood where they discovered additional cases of Zika infection — apparently the first time the Centers for Disease Control and Prevention ever advised people not to travel to a place in the continental United States.
On Thursday the CDC announced the neighborhood tested clear, but scientists would continue to keep a wary eye on it.
Dr. Thomas R. Frieden, the director of the C.D.C., said that the Aedes aegypti mosquito, which transmits the Zika virus, has proved to be a wily adversary in Wynwood, a crowded, urban neighborhood in north Miami where all the cases were found. The mosquito may be resistant to the insecticides being used or may be able to hide in standing water.
Florida officials says the number of Zika cases caused by local mosquitoes has risen to 16 from the four announced last Friday -- 13 men and three women. They declined to say whether any of the women were pregnant. All of the cases were in Wynwood.
The 12 newly identified patients were most likely infected weeks ago, as early as mid-June, the officials said.
But the new information casts doubt over the effectiveness of weeks of intensive mosquito-control efforts in South Florida and raises questions about tourism in the state, which drew more than 100 million visitors last year.
In fact, of the 422 Zika cases in Florida overall, 55 involve pregnant women.
“Aggressive mosquito control measures don’t seem to be working as well as we would like,” Frieden told the press.
“We advise pregnant women to avoid travel to this area,” Frieden said, “and pregnant women who live and work in this area and their partners to make every effort to avoid mosquito bites and practice safe sex.”
Our question to readers, then, is this: