Mosquito-Borne Disease Rising in South Florida

The novel coronavirus isn’t the only public health challenge facing Miami-Dade County. West Nile virus and dengue fever are spreading throughout the area and the county is under a mosquito-borne illness alert.

Mosquito season in South Florida can begin as early as February and stretch far into fall due in part to hurricane season, which peaks in the region late August through October. Heavy rains leave standing pools of water behind, creating a huge breeding ground for the insects.

According to Miami-Dade County Mosquito Control Division Director Dr. William Petrie, WNV cases are spread across Florida and throughout the United States.

How Mosquito-Borne Illnesses Spread

“It’s fairly sporadic geographically,” said Petrie of WNV. “It’s a disease of birds. Birds are migrating and nesting at certain points of the year. [It’s cyclical.]”

Petrie said Culex quinquefasciatus mosquitoes, or “southern house mosquitoes,” are the primary cause of WNV in Miami-Dade, since they can breed in freshwater environments. Female mosquitoes feed off infected birds and later transmit the virus to people when they get bitten.

Mosquito Control has attempted to contain the virus by spraying Bacillus thuringiensis israelensis (BTI), a bacteria-based larvicide, into area storm drains. The substance can kill mosquito larvae while leaving people and animals unharmed in the process.

Larva breeding habitats are often located in foul, filthy water. Petrie attributed the sharp uptick in WNV cases in the county to recent weather conditions in South Florida.

“We had a very, very dry spring, almost a drought,” Petrie said. “We then had downpours,” which caused mosquitoes to come out in full force.

The county is continuing to set up mosquito traps that will later be collected and sent to the Centers for Disease Control and Prevention (CDC) for further inspection.

Although symptoms vary from person-to-person, there isn’t a vaccine or cure for the virus.

Protect Yourself & Your Family

Local health officials are encouraging people to exercise “Drain and Cover,” according to the Florida Department of Health in Miami-Dade.

“Drain” water from any outdoor items that have collected rain during a rainstorm, such as flowerpots, car tires, pool covers and garbage cans.

“Cover” your arms and legs with long sleeves and pants to minimize the risk of getting bitten by infected mosquitoes. Wearing bug repellent is also highly recommended by the CDC.

The rise in West Nile virus and dengue fever cases is a distressing blow to South Florida, where coronavirus is a grave concern for local residents.

Confirmed COVID-19 cases in Miami-Dade already top 164,000, with nearly 3,000 deaths and counting. Fortunately, county resources being poured into combatting the pandemic has not caused the mosquito eradication budget to take a hit. These budgets are separate, according to Public Information and Outreach Division Director (PIO) Gayle Love. Solid Waste Management Support Services reports that $11.332 million are dedicated to mosquito control in fiscal year 2019-2020, an increase from prior years.

“I think the positive aspect of Miami-Dade County’s budget is the significant increase over the past few years [dedicated to mosquito-borne disease], whether it was caused by Zika or not, and the considerable increase in personnel which enables us to better deal with such challenges as WNV,” said Petrie.

Symptoms & Signs

West Nile virus symptoms include headache, fever, pain and fatigue, while dengue fever symptoms vary from swollen lymph glands to fever and joint pain, according to public health sources.

There are reportedly 46 suspected dengue fever cases in Miami-Dade County and one confirmed case, according to Mosquito Control Clerk Carlos Primo. The type of mosquito that spreads dengue bites more frequently in the day and mostly outdoors, but can breed indoors and is capable of biting anyone throughout the day.

Individuals  experiencing mosquito problems in the county should dial 311 for help.

“Be on the lookout for dead blue jays and crows,” Petrie said. “Those birds are susceptible to West Nile and can be a warning sign.”