Thursday, February 18, 2010

Since Florida's earliest days, mosquitoes have played a major role in our history as a pest and carriers of diseases like yellow fever and malaria. The mosquito that carries most of the diseases in the Keys, the Aedes aegypti, lays its eggs in man-made containers. This is the mosquito that can transmit dengue fever.

Florida Keys Mosquito Control (FKMC) has an outstanding program for controlling these mosquitoes and the 45 other mosquito species in the Keys. Surveillance for mosquito larvae in backyards Keyswide is part of our domestic program, which aims at eliminating mosquitoes before they become adults. By dumping water-holding containers, treating water with bio-friendly bacteria that attack larvae, and introducing larvae-eating gambusia fish into ponds, homeowners are relieved of nuisance and disease-carrying mosquitoes. As a result, FKMC does less spraying for adult mosquitoes.

In September of 2009, the first dengue case was reported in the Old Town area of Key West. In this dense setting, the dengue-carrying Aedes aegypti mosquito can thrive in containers and resting places like porches, under homes and in lush landscaping. Because it was September, many "snowbirds" were absent and locked gates prevented FKMC from inspecting backyards. Abundant rainfall exacerbated the problem; time was of the essence. With public health and safety in mind, FKMC did not wait for confirmation on that first case, but immediately launched a full attack on this disease-carrying mosquito.

FKMC began nightly spray-truck and morning helicopter missions. Domestic inspectors began a full walking door-to-door sweep of the Old Town area. The sweeps conducted in autumn helped eliminate the numerous water-holding containers and educate homeowners about the importance of mosquito and dengue prevention. Our goal was to speak to as many residents as possible. An informational DVD, dengue flyers and door-hangers about what was found on the property were left at every home. Absent homeowners were contacted and asked to unlock their gates.

When other possible cases were identified, sweeps expanded into Stock Island and Key Haven. Along with dumping containers, inspectors hand-sprayed under porches and other hard to reach areas when adult mosquitoes were discovered. Traps were set throughout Key West, Stock Island and Key Haven to catch and count the potential carriers for dengue. FKMC reduced the number of Aedes aegypti in the area using all the integrative pest management strategies and methods available, and hopefully limited the spread of dengue.

Although mosquito-borne diseases have been absent from many residents' minds, Keys mosquitoes always have the potential to carry diseases like yellow fever, malaria, West Nile virus and dengue -- and many more diseases are making their way around the globe. Mosquito surveillance through our field program and domestic program has allowed for effective and timely control in our sensitive environment. The domestic program, which previously consisted of 15 inspectors Keyswide, has been expanded by eight new inspectors. Additional domestic inspectors covering more ground up and down the Keys will eliminate the breeding sites for the Aedes aegypti mosquito, while helping to control the spread of dengue.

FKMC will be measuring the population of Aedes aegypti through another sweep starting the week of Feb. 22. Using census data, homes will be randomly selected and properties inspected. The survey sweep will collect baseline data to later assess the infestation rate, which is the percentage of homes found with Aedes aegypti. We are working to bring last summer's infestation rate of 15-20 percent down for 2010.

Controlling dengue is a collective effort among homeowners, Mosquito Control and the Monroe County Health Department. Our community must recognize that dengue will not go away on its own and FKMC can never eliminate all mosquitoes. Dengue is a man-made problem; the most common breeding sites of Aedes aegypti include plastic containers, plant trivets, buckets, flowerpots, fountains, garbage cans, untreated spas and pools, birdbaths and tires. Without containers, the life cycle of the Aedes aegypti mosquito would slow down or stop.

Residents need to help our efforts by removing standing water on a weekly basis and after every rainfall, and by keeping FKMC informed of problems. Please call Mosquito Control (305-292-7190) when mosquitoes become active, as we rely on service requests, landing rate counts, traps and rain data to help guide our efforts. Let's stop dengue from happening in the Keys.

Coleen Fitzsimmons is a biologist in charge of public outreach for the Florida Keys Mosquito Control District.