Collier, Lee mosquito control on alert after dengue cases reported in Florida Keys

Collier’s mosquito control district is at the ready after a local outbreak of dengue was reported in the Florida Keys.

The Florida Department of Health in Monroe County confirmed a total of 16 cases in the Keys on Friday. All indications show the two most recent cases were locally acquired, a news release from the department says.

The non-contagious tropical disease occasionally hits Florida every few years through travel-related cases, said Scott Michael, a biology professor at Florida Gulf Coast University who researches anti-virals and vaccines for mosquito-borne viruses.

“When you start to get local transmission, carried by local mosquitoes, the cases are related,” Michael said.

Collier County ramping up testing 

The Collier Mosquito Control District has not identified signs of dengue-infected mosquitoes in the county.

“We are ramping up capabilities for dengue virus testing because we know it is in the state,” said Keira Lucas, the director of research at the Collier Mosquito Control District.” Every week, we bring in mosquitoes and test them.”

The district collects mosquitoes from eight traps throughout the county and can test in-house for species that may carry dengue, specifically Aedes aegypti and Aedes albopictus.

“Because we can do our own testing, we get results the same day we bring our traps into district,” Lucas said. “If we had a positive, we would initiate our treatments and our plan of action immediately, then send samples to state for verification.”

If the district does identify an active transmission of dengue in the county it would implement an adulticide mission as well as a larvicide mission to target the Aedes species. Adulticide is an insecticide used to target fully grown adult mosquitoes as opposed to larvicide, which is used to target larva.

Lee County paying attention

Lee County Mosquito Control District is also aware of the dengue outbreak in Monroe and taking its own precautions. Lee's district also traps and monitors Aedes aegypti mosquitoes in its in-house lab.

"It's something we are paying close attention to," said Deputy Director Eric Jackson. 

While there have been no locally transmitted cases in Lee, Jackson said someone who suspects they have dengue should immediately consult with their health care professional.

It’s unlikely that dengue would travel through mosquito populations from Monroe to Collier, Michael said.

How mosquitoes spread dengue

“It usually spreads by transport of people or by transport of mosquitoes or their eggs,” he said.

It’s simply travelers: people going to the Keys can bring dengue to wherever they came from and it’s unlikely a mosquito will fly from the Keys to Naples, he said.

The dengue-carrying species live in close association with humans, Lucas said. The mosquitoes breed in containers that hold standing water, so residents should be mindful to empty what standing water they can.

“The best way to prevent this type of mosquito is get rid of the source by removing standing water,” she said. “These are typically things like buckets, pots and saucers under potted plants. (Mosquitoes) can breed in something as small as a bottle cap.”

Lucas also recommends Bacillus thuringiensis israelensis (BTI) larvicide for larger bodies of water. BTI larvicides can be found at any home improvement store.

The district also runs a free mosquito fish program for residents.

“(The fish) are perfect for fountains, bird baths, rain barrels and small ponds,” Lucas said.

"We’re starting to resume our normal rainy period," Jackson said, "and when you have consistent rains, this is when that water collects around houses."

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Other ways of preventing mosquito bites include: ensuring intact screens, wearing long sleeve shirts and pants.

The mosquitoes that may carry dengue feed at dawn and dusk and are found in shady areas during the day. Michael recommends trying to avoid being outside around those times or using a mosquito repellent with DEET.

Dengue can take a week or so to develop in humans, and the majority of cases are mild or asymptomatic, Michael said. Severe cases have been called “bone-break fever” because of the intense pain in an infected person’s bones.

There are no respiratory symptoms associated with dengue, a Monroe County news release says, but the disease does present itself as flu-like with “aches and pain, fever and sometimes a rash.”

There have been two recent outbreaks in Florida’s recent history. In 2009, Monroe County reported 85 dengue cases, and then in 2013, 22 cases were reported in Martin County.

Michael has been studying dengue for more than 15 years and has an antiviral drug licensed to a company to get into human trials and a vaccine in non-human trials. Both are moving forward, he said.

Did you know?:Collier Mosquito Control District using fish to fight the bite

And:Collier Mosquito Control District adds $3.4M helicopter to its fleet

Dengue quick facts:

• Dengue is carried by Aedes aegypti or Aedes albopictus, which can also spread Zika and chikungunya.
• Dengue is reported in about 400 million people each year, according to the CDC. A quarter of the infected get sick and 22,000 can die.
• There are four related dengue viruses, meaning someone can be infected as many as four times in their lifetime.
• Mosquitoes typically carrying dengue are dawn and dusk feeders, usually only ranging about 200 yards from their breeding habitats, according to the Collier Mosquito Control District.

Karl Schneider is an environment reporter. Follow him on Facebook and Twitter: @karlstartswithk, email him at kschneider@gannett.com

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