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Mosquitoes now a year-round threat to Miami-Dade County

A new study shows that mosquitos in South Florida are making urban neighborhoods a permanent home.

Examining more than two years of data, public health researchers with the University of Miami Miller School of Medicine determined there are more than three dozen types of mosquitos prevalent in South Florida, including species that carry and transmit disease, such as Zika.

The team worked in collaboration with the Miami-Dade County Mosquito Control Division, and utilized data from the county’s mosquito surveillance program put in place following the Zika virus outbreak that occurred in 2016.

“We found 41 species of mosquitoes in abundance, including Aedes aegypti, which can transmit viral diseases like Zika, dengue fever, and chikungunya,” said André Wilke, a post-doctoral associate in the Division of Environment and Public Health in the Department of Public Health Sciences at the Miller School. “These species were present in high numbers year-round, indicating there is no longer a summer ‘mosquito season’ here.”

Wilke was the lead author of the study, “Community Composition and Year-Round Abundance of Vector Species of Mosquitoes Make Miami-Dade County, Florida, a Receptive Gateway for Arbovirus Entry to the United States,” published in June in Nature/Scientific Reports.


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“Our results also show that the five mosquito species that may carry these viruses, including Aedes aegypti andCulex quinquefasciatus, are well adapted to urban environments,” said study co-author John C. Beier, professor and chief of the Division of Environment and Public Health.

Beier said the U.S. Centers for Disease Control and Prevention supports the ongoing collaboration between the Miller School and the Miami-Dade County Mosquito Control Division.

“Establishing a state-of-the-art surveillance system provides a foundation to inform and guide public health decision-making,” Beier said.

Study co-author Chalmers Vasquez, director of research for Miami-Dade County Mosquito Control, said a total of 2.7 million mosquitoes were collected from August 2016 to November 2018 in 191 traps.

“We covered the entire county with an emphasis on Miami Beach and Wynwood, as well as Little River,” he said. “These communities experienced locally transmitted Zika cases in 2016, and have large numbers of visitors who may bring in mosquito-borne arborviruses from other countries.”

Vasquez said every week samples of trapped mosquitoes are sent to state and federal laboratories for viral testing and screening. To date, there have been no indications of active local transmission.

But the high volume of international air travel to Miami from the Caribbean region and Latin America substantially increases the risk of introduction of arboviruses to the U.S., said the researchers.

“Continued surveillance, public education, environmental ordinance, and active control of mosquito populations are critical for the prevention of viral outbreaks,” they concluded.

Most recently, health officials reported the detection of a dangerous and potentially deadly mosquito-borne virus in the state of Florida found in sentinel chickens. The eastern equine encephalitis virus is a rare disease that causes symptoms of headache, high fever, chills and vomiting. More severe symptoms include disorientation, seizures and coma.

“It’s good for people to be aware of this, but there is minimal risk for human infection. EEE has been around for years, and on average there are only seven reported cases of it per year,” said Beier.

Although it is unlikely for it to spread, Beier urged everyone to visit the Centers for Disease Control and Prevention website to get informed on how to avoid getting bitten by mosquitos.  For more information visit: