Zika now on U.S. mainland: 4 in Miami bitten by infected mosquitoes

Four people in Florida are believed to have contracted the Zika virus from infected mosquitoes in Miami, marking the first documented local transmission of the virus on the mainland United States, health officials announced on Friday.

Officials from the Florida Department of Health would not comment specifically on the cases, but in a release said, “the department believes that active transmission of the Zika virus are occurring in one small area in Miami-Dade County, just north of downtown.” The infected were three men and one woman, Florida Governor Rick Scott said in a statement.

The four were bitten while they were at work in the Wynwood area of Miami, a popular dining, arts and entertainment district which has a large Puerto Rican population. Health officials are going door-to-door in the one-square mile area alerting residents. Because at least one of the people lives in Broward County, epidemiologists are also focusing on the immediate area around the person's home. They are also collecting urine samples of people in the area to determine whether more people have gotten the virus. Georgia has similar protocols if and when the virus arrives in the state.

Friday’s announcement signals a shift in the battle against the Zika epidemic in the U.S.. Previously, the Zika virus had been contracted by those who had travelled abroad to affected countries - mostly Latin America and the Caribbean - or though sexual contact with someone infected. Federal officials had long warned Zika would reach the mainland this summer.

“Zika is now here,” said Dr. Tom Frieden, head of the Centers for Disease Control and Prevention during a press conference.

The infections occurred in early July, but the people did not get sick until a week later, said Frieden. Most people who get Zika show no symptoms. Those that do usually experience fever, joint pain, conjunctivitis, headache and rash. Frieden said more infections are likely. Florida already has had about 400 cases of travel-related or sexually transmitted Zika.

Frieden has said repeatedly that while it is possible to try to control mosquito populations, the two mosquitoes that carry the virus, the Aedes aegypti and Aedes albopictus, are the "cockroaches of mosquitoes," and are impossible to completely eradicate. They only travel about 164 yards in a lifetime. Both mosquitoes are found in Georgia.

While Miami has deployed trucks to spray for mosquitoes, federal health officials said it’s hard to find individual mosquitoes that have the virus.

“It’s like finding a needle in a haystack,” Frieden said.

So far, the Florida health department said, no mosquitoes collected in the immediate area of infection have shown signs of the virus. Still, health officials believe the Miami cases are not from sexual transmission or are travel related. Apparently, local doctors brought the cases to the health department’s attention after treating patients who believed they had been exposed to the virus.

Miami-Dade and Broward county areas are now screening blood supplies and rejecting blood donations from anyone who lives in the affected areas.

Zika has spread rapidly in the Americas. In Puerto Rico alone, there have been 5,000 cases and the disease continues to spread. As of last week, there were 46 confirmed travel-related cases of Zika in Georgia. Now that mosquitoes in Florida are spreading the disease, it presents a worrisome and frightening potential problem for neighboring Georgia.

Though Zika has been related to two adult deaths, one in Puerto Rico and one travel-related case in Utah, Zika is most dangerous for pregnant women and people who are trying to get pregnant. Infected men and women can pass it along to their male or female partners through sex. The disease causes a range of devastating birth defects, including microcephaly, a condition that causes a fetus' skull to collapse around its under-developed brain. Already, at least 12 babies have been born in the U.S. with the condition, though those cases were largely believed to have been travel-related. And some babies who were exposed to Zika in utero may not show health problems for weeks, months or years.

The CDC hasn’t issued a travel advisory for Miami, warning pregnant women or those who want to become pregnant not to visit the city. Frieden said that if there are more cases of Zika after Miami’s aggressive mosquito control efforts have slowed, then the CDC may reconsider the travel advisory. For now, however, pregnant women in all states, including Georgia, are advised to wear insect repellent with DEET whenever they are outside.

Congress adjourned earlier this month for seven without approving any funding to fight Zika, despite the Obama administration's request for $1.8 billion to fight the disease. Federal health officials have pleaded with Congress to approve the request, saying it is needed not only for vaccine research, but to help states prepare for the arrival of Zika.

“Large spread transmission of the virus in the U.S. is unlikely, but not impossible,” said Frieden.

Still, the virus isn’t expected to blanket the U.S. as quickly as it has other countries, health officials have said, because unlike in others, many homes here have screens on windows, air conditioning, and other barriers that control mosquitoes.