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MONDAY, Aug. 1, 2016 (HealthDay News) -- The number of local transmissions of the mosquito-borne Zika virus in South Florida has apparently increased to 14, Gov. Rick Scott said Monday.
Scott said he has asked for a federal emergency response team to help the state respond to the outbreak of the virus that is harmless to most people but can cause devastating birth defects.
State health officials on Friday reported four probable cases of local transmission of Zika in a 1-square-mile neighborhood of Miami called Wynwood. If confirmed, these would be the first cases of local transmission of Zika virus by mosquitoes in the continental United States. Most Zika infections have occurred in Latin America and the Caribbean. Brazil has reported the vast majority of cases and the birth defect microcephaly, which results in newborns with smaller-than-normal heads and underdeveloped brains.
Scott said Monday that the new cases are clustered in the same 1-square-mile neighborhood identified last week. Florida health officials said in a news release Monday that they believe active transmissions of Zika are occurring only in that area.
"Today, DOH (the Department of Health) has confirmed that 10 additional people have contracted the Zika virus locally, likely through a mosquito bite," Scott said. "DOH has been testing individuals in three locations in Miami-Dade and Broward Counties for possible local transmissions through mosquito bites. Based on DOH's investigations, two locations have been ruled out for possible local transmissions of the Zika virus. DOH believes local transmissions are still only occurring in the same square-mile area of Miami."
Federal health officials said Friday that transmission of Zika virus by mosquitoes in the continental United States was not unexpected.
"At CDC, we have been saying for months, based on experience with chikungunya and dengue -- viruses spread by the same mosquito that spreads Zika -- that individual cases and potentially small clusters of Zika are possible in the U.S.," CDC Director Tom Frieden said during a Friday media briefing.
"As we have anticipated, Zika is now here," Frieden said.
The CDC said it expects to see cases of local transmission of the Zika virus this summer in warm, humid southern states such as Florida, Louisiana and Texas. The virus is typically transmitted through the bite of Aedes mosquitoes.
But U.S. officials said they don't expect to see a Zika epidemic in the United States similar to those in Latin America. The reason: better insect control as well as window screens and air conditioning that should help curtail any outbreaks.
Miami-Dade County is one of the busiest entry points into the United States from countries where the Zika virus is circulating, making it one of the areas most at risk for a Zika outbreak, The New York Times reported.
The CDC also announced Friday that Zika infections had skyrocketed to epidemic levels in Puerto Rico.
Positive tests for people with suspected Zika infection increased from 14 percent in February to 64 percent in June in Puerto Rico. As of July 7, Zika had been diagnosed in 5,582 people in Puerto Rico, including 672 pregnant women, the CDC said.
Aedes mosquitoes feed primarily on human blood, and tend to breed in small pools of water found in local neighborhoods.
The mosquitoes have a short travel range, and Florida officials are describing the infections as a "small case cluster" that do not indicate widespread transmission.
"The Aedes aegypti mosquito does not travel more than 150 meters in its lifetime, and often quite a bit less than that," Frieden said.
Responding to the possibility of local transmission of the Zika virus in South Florida, the U.S. Food and Drug Administration said Thursday that it was asking all blood centers in Miami-Dade and Broward counties to stop collecting blood immediately. They can resume collections once the blood centers put in place testing for each unit of blood collected.
The FDA urged nearby counties to take similar precautions to safeguard blood supplies.
So far, the 1,658 Zika infections reported in the United States mainly have been linked to travel to countries with Zika outbreaks in Latin America or the Caribbean.
In addition to mosquitoes, the Zika virus can be transmitted through sex. The CDC has reported 14 cases of sexually transmitted infections. These infections are thought to have occurred because the patients' partners had traveled to countries where Zika is circulating, the CDC said.
The Zika virus also has been linked to a rare paralyzing condition called Guillain-Barre syndrome.
The CDC advises pregnant women not to travel to an area where active Zika transmission is ongoing, and to use insect repellent and wear long pants and long-sleeved shirts if they are in those areas. Partners of pregnant women are advised to use a condom to guard against sexual transmission during pregnancy.
State officials along the Gulf Coast say a lack of funding has hampered their Zika response efforts. President Barack Obama has asked Congress to allocate $1.9 billion to combat the Zika threat, but federal lawmakers have yet to agree on a spending package.
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SOURCES: Aug. 1, 2016, news release, Florida Department of Health; July 29, 2016, media briefing with Tom Frieden, director, U.S. Centers for Disease Control and Prevention; U.S. Centers for Disease Control and Prevention, news release, July 29, 2016; U.S. Food and Drug Administration, news release, July 28, 2016; The New York Times