No Zika detected in Florida mosquitoes so far this year, officials say

With summer approaching, Florida health officials are taking steps to prevent another outbreak of the Zika virus. State and local officials have been monitoring for the virus in both humans, who could pick up the virus abroad, and in mosquitoes, which could transmit the illness to humans.

Officials from the Florida Department of Agriculture and Consumer Services said Thursday that no Zika virus has been detected in any mosquitoes tested this year. Since last year's outbreak began, they have tested 90,000 individual mosquitoes which represent 6,500 mosquito pools. There is no longer an ongoing outbreak in Florida.

"As we enter into the warmer months, it's especially important that Florida communities are equipped with the knowledge and resources they need for their Zika-related response efforts," said Commissioner of Agriculture Adam H. Putnam said in a statement Thursday.

Last year, officials in southern Florida had to combat outbreaks of locally transmitted Zika virus in four areas in or near Miami. In 2016, a total of 1,118 people in Florida were diagnosed with the disease.

This year, there have been no outbreaks of locally transmitted Zika, although 33 people have been diagnosed with the disease in Florida after being infected outside the U.S. Zika virus usually causes mild symptoms in adults, but it has been linked to serious birth defects, including microcephaly and other brain defects, according to the U.S. Centers for Disease Control and Prevention.

The virus is spread primarily via the Aedes aegypti mosquito, which been called a "cockroach" mosquito for its ability to live indoors and reproduce even in tiny pools of water. Mosquitoes like the Aedes aegypti are the primary way the Zika virus is spread, although the disease can also be transmitted through sexual contact.

The Aedes aegypti mosquito has also been found to be resistant to pesticide spraying. Last year, after locally transmitted Zika was spread in Miami, the U.S. Centers for Disease Control and Prevention said the initial mosquito-control measures were not effective.

"Aggressive mosquito-control measures don't seem to be working as well as we would have liked," now-former CDC Director Tom Frieden told reporters at the time.

Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center, said in an interview during the Zika outbreak last year that the Aedes aegypti mosquito is especially hard to combat for multiple reasons.

"There's a history of Aedes being relatively resistant to conventional pesticide," Schaffner told ABC News. "When we say they're resistant that means the mosquito inherently can shrug off the pesticide."

All outbreaks of locally transmitted Zika in Florida were declared over by last December, six months after the first outbreak was reported in July.