No new case reported this week by Florida Department of Health in Tallahassee
The latest update from the Florida Department of Health in Tallahassee — for the week of July 16 through July 22 — said no new locally acquired malaria cases had been reported in Sarasota County, with the total remaining at seven.
If that trend continues through the next eight weeks — until around Sept. 7 — the county and the U.S. Centers for Disease Control and Prevention (CDC) will be able to declare the outbreak at an end, Jamie Carson, director of the Sarasota County Communications Department, explained during a July 27 webinar that county staff coordinated with the CDC for members of the news media.
The first locally acquired case was identified on May 24, Carson said. The seventh — and, thus far, the last — was confirmed on July 13. Health professionals consider the eight-week timeline to be sufficient to ensure that the local transmission of malaria has ended, she pointed out.
Audrey Lenhart, chief of the Entomology Branch in the Division of Parasitic Diseases and Malaria at the CDC, who also participated in the July 27 briefing, added, “I think that every day that goes by without a new case is promising.”
She noted, “Mosquitoes don’t live a tremendously long time” — typically three weeks, though some can live up to eight weeks. “Truly, every day that goes by gets us closer to feeling confident” that the transmission cycle in Sarasota County has ended, Lenhart said.
In response to a question about whether the eight-week timeline is typical, Lenhart responded, “There’s nothing unexpected about that.” The goal, she continued, is to make certain that all of the mosquitoes carrying malaria have died or been killed.
As long as members of the public keep taking precautions against mosquito bites, and the county’s Mosquito Management Services team continues its work, Lenhart indicated, eight weeks should be adequate.
In response to a question about how well Sarasota County staff has been able to contain the outbreak, Carson of Communications explained that members of the Mosquito Management Services team are “out in the community on a daily basis.” They did not wait until the first case was confirmed, she continued, before stepping up treatment in north Sarasota, where all of the cases have been identified.
Kensington Park and Desoto Acres remain the primary focus of concern, Carson pointed out.
In regard to efforts to prevent mosquito bites among the homeless — as three such individuals have been among those who contracted malaria — Carson said that county staff has maintained outreach to all of the organizations that provide services to the homeless. She added that more than 1,000 cans of repellent have been distributed to homeless individuals, especially in the Desoto Acres and Kensington Park areas, and 60 bed nets had been provided.
Additionally, CDC staff members visited the county this week, Carson continued, to take a look at the Mosquito Management operations.
“It really is an exceptional operation that Sarasota has for mosquito control,” Lenhart said. The fact that the malaria outbreak has been no worse than it has, she added, is “a tribute to their fast action and continued action. “The mosquito populations were reduced significantly …”
“The CDC has been providing some tactical guidance on the spraying operations,” Lenhart said. Nonetheless, she noted, Mosquito Management “has a vast amount of experience controlling mosquitoes,” including those that carry malaria.
She also pointed out that Mosquito Management is using CDC-approved pesticides, which is the county team’s standard practice.
Carson added that the team uses multiple types of insecticides, as mosquitoes over time can become resilient to specific brands. The Mosquito Management staff undertakes routine surveillance to try to ensure that the chemicals are working adequately, Carson indicated.
Additionally, Carson said, the team has stocked more than 15,500 mosquito fish — a species that eats the insects — at 22 sites with ponds or other bodies water. Mosquito Management is “using everything in its arsenal,” she pointed out.
Carson is inviting all interested persons to attend a Mosquito Management Services program that has been planned for the public on Friday, Aug. 4, at the Robert L. Taylor Community Complex in Sarasota. The event will take place from 5:30 to 7 p.m. The facility stands at 1845 34th St. in Sarasota.
“Come meet this dedicated staff and learn about their department operations and how you can protect yourself from mosquito bites,” county Facebook page posts say.
Continued treatment efforts and ‘genome sequencing’
During the July 27 briefing, Carson of Communications noted that routine county mosquito control operations remain underway.
The most recent Sarasota County Government Facebook page update about mosquito spraying was posted on July 26, The Sarasota News Leader found. That said, “A ground treatment (truck) to kill adult mosquitoes is scheduled tonight after 9:15 p.m. in Venice. Area of treatment is West of [U.S. 41], between Seafox Rd and Scenic Dr (Zone V8). Completion of the mission will be weather permitting.”
Two days earlier, on July 24, a post noted, “A ground treatment (truck) to kill adult mosquitoes is scheduled tonight after 9:15 p.m. in Urban Sarasota. Area of treatment is east of Sawyer Rd, between Clark Rd and Bee Ridge Rd. Zones S21 & S22 (partial). Completion of the mission will be weather permitting.”
As always, the posts added, “Visit our ‘Planned Spray Mission Map’ at www.scgov.net/mosquito for more details about spray time, pesticide applied and treatment location. You may also ‘Register for Spray Notifications’ or ‘Request Service’ to report a major mosquito population increase in your area. #SRQCountyMMS.”
In response to another question during the briefing, Lenhart explained that CDC staff is conducting sequencing of the genome of the parasites found both in the individuals who contracted malaria and in the mosquitoes that Mosquito Management has sent to the agency. The goal, she said, is “to confirm that we do have a closed transmission loop.”
(The National Human Genome Research Institute explains, “The genome is the entire set of DNA instructions found in a cell. In humans, the genome consists of 23 pairs of chromosomes located in the cell’s nucleus, as well as a small chromosome in the cell’s mitochondria. A genome contains all the information needed for an individual to develop and function.)
If the sequencing shows the genomes are sufficiently similar, Lenhart added, “That just increases our level of confidence that it was a closed transmission loop.”
Asked how far along that sequencing operation is, Lenhart replied that the CDC lab handling the work “is trying some new protocols,” so she expects it will take several more weeks before the results are available.
In response to a question about whether this outbreak is similar to the previous one in Florida, which occurred in Palm Beach County in 2003, Lenhart said, “I was not at the CDC [then].” However, she added, “All of these events are learning experiences for us.”
The key difference in this Sarasota County situation, Lenhart noted, is that Mosquito Management Services efforts, including providing mosquitoes to the CDC for testing, to help guide the response.
Carson also took the opportunity during the briefing to encourage all county residents to continue to try to avoid mosquito bites, following guidelines that the Florida Department of Health in Sarasota County (DOH-Sarasota) and the CDC have provided. If it is not necessary for someone to be outside during the peak period for mosquito activity — from dusk to dawn — then people should remain indoors, Carson said.
“This [outbreak] is an excellent reminder of the importance of avoiding mosquito bites,” Lenhart added.
Guidelines for preventing mosquito bites
Since the first county case was identified in late May, DOH-Sarasota has offered the following tips for preventing mosquito bites:
- Use mosquito repellent that contains DEET (10-30%), picaridin, oil of lemon eucalyptus, para-menthane-diol, 2-undecanone or IR3535.
- “Wear long sleeves and pants.
- “Check and repair screens on doors and windows to prevent mosquitoes from entering your home.
“To help reduce the population of mosquitos around your home,” the DOH-Sarasota staff says, “please drain and cover areas around your home.” Health officials also point out that mosquitoes reproduce in freshwater from rainstorms, sprinklers and other sources. “Drain pools of freshwater around your home and yard,” they advise the public. “Empty pet bowls, garbage cans, garbage can lids, bottles, tires, and anything where freshwater has accumulated.”
Further information on mosquito prevention in Florida may be found here, DOH-Sarasota says. That link also offers materials that can be displayed or distributed in communities, Health Department staff notes.
More information about malaria worldwide may be found through the CDC.