Federal officials are urging residents in Florida to take additional precautions after state health officials on Friday confirmed that four South Florida cases of the Zika virus are the first in the continental United States known to have been transmitted by local mosquito bites.
“All the evidence we have seen indicates that this is mosquito-borne transmission that occurred several weeks ago,” said Tom Frieden, director of the U.S. Centers for Disease Control and Prevention.
Four people in Dade and Broward counties were infected in early July, got sick a week later and were diagnosed a couple of days after that, Frieden said during a conference call with reporters on Friday.
Two of the individuals were bitten while in their respective workplaces, which are located in a 1-square-mile area of Miami-Dade County, just north of downtown Miami.
That area, part of the Wynwood neighborhood, is now the focus of an intense public health effort to kill any Zika-carrying mosquitoes and to determine how many other people in the area might also be infected.
As of July 27, none of 1,658 reported cases of Zika in the continental United States and Hawaii resulted from bites by local mosquitoes, the CDC reported. The four new South Florida cases herald a turning point in the outbreak that Frieden and others had long warned of.
“These cases are not unexpected,” Frieden said. “At CDC, we’ve been saying for months that individual cases and potentially small clusters of Zika are possible in the U.S. As we have anticipated, Zika is now here.”
Zika can cause microcephaly, a disease that produces abnormally small heads in newborns of infected mothers.
Frieden said his staff is doing their best to provide resources to states as needed, but the failure of Congress to provide adequate emergency funding has left the CDC shorthanded as the mosquito season kicks into high gear.
“If we had more resources, we would be able to mount a more robust response,” Frieden said, adding that his agency needs an infectious disease rapid response fund to battle public health threats, such as Ebola and Zika.
Congress left town for their summer recess earlier this month without passing Zika relief legislation sought since February by President Barack Obama. Obama wanted $1.9 billion in emergency funding to address the Zika threat through vaccine development, mosquito abatement, contraception and maternal care.
But Senate Democrats recently rejected a $1.1 billion Zika bill from Republicans in the House of Representatives because it would have barred private family-planning organizations, including Planned Parenthood, from getting federal funds to provide Zika-related reproductive health services. The measure also would have defunded parts of the Affordable Care Act and would have allowed Confederate flags to be posted in military cemeteries.
In a statement, U.S. Rep. Debbie Wasserman Schultz said she and fellow Democrats “will continue to pressure Speaker Ryan and his Republican colleagues for more funding to combat Zika until they stop playing partisan politics and start doing their jobs.”
Congressman Vern Buchanan, R-Sarasota, originally supported Obama’s call for $1.9 million in funding and later supported the disputed House Zika bill that Senate Democrats rejected.
“This is exactly what the nation’s top disease fighters alerted Congress about for months,” Buchanan’s statement said. “It’s critical now that we immediately direct all necessary federal resources to this health crisis to protect the public. Millions of Floridians – and Americans at large – are at risk as the hot summer months roll on and mosquitoes continue to spread.”
The disease can be spread by the bite of a mosquito, but also can be transmitted sexually from an infected partner.
Frieden said he doesn’t expect to see widespread transmission of the Zika virus in the U.S. the way it has spread in Latin America, Puerto Rico and other parts of the Caribbean.
He also has not issued a travel restriction for the Miami neighborhood.
“Based on what we know now, we’re not issuing travel guidance, but that could change depending on events as they occur here and elsewhere in the U.S., Frieden said.
Although no infected mosquitoes have turned up in traps in the targeted neighborhood, Frieden said significant numbers of Aedes aegypti mosquitoes, which carry the Zika virus, have been found in the square-mile area. Workers have been spraying the area with insecticide to kill adult and larval mosquitoes and are eliminating standing water sources where mosquitoes typically breed.
Health officials are also going door-to-door collecting urine samples from residents to make sure no other infections have occurred because four out of five people who carry the Zika virus will not show symptoms. Frieden said he wouldn’t be surprised if the screening efforts turn up even more mosquito-borne infections in the coming weeks.
“If, however, we were to see cases in this area in people infected after the mosquito control efforts were undertaken, this would be of concern and warrant further advice and action,” Frieden said.
Area blood banks have stopped accepting donations from persons in the targeted neighborhood and are also testing their supplies to insure that no Zika-infected blood is given to patients. Health officials are also encouraging doctors to be on the lookout for patients with symptoms of Zika and are asking all pregnant women in Florida to consider being tested for the virus.
At the request of state officials, the CDC has sent a medical epidemiologist to Miami to assist investigators.
Confirming mosquito-borne Zika infections is a tricky proposition, Frieden said. Unless infected mosquitoes are discovered in traps – which is unlikely – investigators determine a case to be transmitted by mosquito by eliminating other sources of infection, like sexual contact with an infected person or travel-related infections that occurred while visiting locales where Zika infections are already occurring.
Because the Zika-carrying mosquitoes seldom travel more than 150 meters in their lifetime, spraying is an effective method of eliminating clusters of the infected insects, Frieden said.
Health officials are urging people to apply insect repellent each day to exposesd skin, wear long pants and long-sleeved shirts and stay indoors or in screened-in areas as much as possible.