(CNN) Mosquitoes carrying the Zika virus have been identified in Miami Beach, the Florida Department of Agriculture and Consumer Services said Thursday.

It's the first finding of Zika-carrying mosquitoes in the continental United States.

The three mosquito samples that tested positive were from the area in Miami Beach that was previously identified as an area of local transmission

"This is disappointing but not surprising," said Adam Putnam, the Florida commissioner of agriculture.

"We already knew because of human cases [that] Zika transmission was occurring; positive pools are just further indication that transmission is still occurring in the area," Centers for Disease Control and Prevention spokeswoman Candice Hoffmann said.

It was unclear when those mosquitoes were caught, although spraying has been ongoing throughout the area.

One of the mosquito traps with Zika-infected mosquitoes was in the botanical gardens, according to Miami-Dade County Mayor Carlos Gimenez. The location of the other two traps where infected mosquitoes were caught was not disclosed. Sixteen other mosquito traps in Miami-Dade tested negative, Gimenez said, adding that tests on additional mosquitoes are underway.

Gimenez emphasized that the finding of these mosquitoes will not change current efforts to fight the virus and the mosquitoes that carry it. "The message remains the same: If you have standing water, drain it, cover it; please wear adequate clothing; wear repellant," he said.

Dr. Chris Braden, director of the division of foodborne, waterborne and environmental diseases at the CDC's National Center for Emerging Zoonotic and Infectious Diseases, said the finding helps inform and focus mosquito-control measures.

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On August 11 , the CDC warned pregnant women to avoid a 1½-square-mile area of Miami Beach after the state confirmed local transmission of the virus there.

On July 29, Scott announced that the first local transmission of the virus in the continental United States had occurred in the Wynwood neighborhood, north of downtown Miami.

Aggressive mosquito-control measures were begun, including mosquito spraying in the area.

At the time, CDC Director Dr. Tom Frieden said that finding a Zika-carrying mosquito is like finding a needle in a haystack, and doing so is not necessary to confirm local mosquito transmission.

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To date, there have been 49 locally transmitted cases of the virus in Florida, according to the state Department of Health. Forty-two of those have been in Miami-Dade County. Florida is the only state in the continental United States where local transmission has occurred.