Latest case linked to same area as others — north of Fruitville Road between U.S. 41 and I-75, especially Desoto Acres and Kensington Park
With the Florida Department of Health in Tallahassee this week having confirmed a seventh case of malaria in Sarasota County, the county’s Mosquito Management Services staff is making another effort to treat areas north of Fruitville Road, between U.S. 41 and Interstate 75, where all of the cases originated.
That was the news that Wade Brennan, manager of Mosquito Management Services, delivered during a July 18 press conference.
The state Health Department’s Arbovirus Surveillance Report for the period of July 9-15 again made it clear that the Sarasota County resident confirmed with malaria had acquired the disease locally, instead of potentially from travel outside the area.
As soon as he and his staff learned of the new case, Brennan said during the press event, “We started doing additional treatments in that [affected] area.” Kensington Park and Desoto Acres remain the primary focus of concern, he pointed out.
“We notified all the public that live in that immediate area” about the new case, he added. Additionally, Mosquito Management staff “did a truck treatment” on the night of July 17 in that section of the county, Brennan noted.
The smaller the area on which to focus treatment, he emphasized, “the better the job we can do.”
He did acknowledge that pesticides do not work indefinitely. “We have to go back” and make certain that areas previously treated have not developed new problems, he said.
As part of that process, he explained, staff members are reviewing aerial photos, looking for bodies of water that they might have missed in earlier rounds of spraying.
Additionally, Brennan noted, the Florida Department of Health in Sarasota County (DOH-Sarasota) has been providing homeless individuals with mosquito netting and repellent. “We have a lot of different people that are being exposed to mosquito bites …”
Asked about two homeless persons who contracted malaria, Brennan explained that they were not among the first cases identified in the county this spring. Instead, he added, they were mixed in among the others. “There’s no trend.”
(Chuck Henry, director of the county’s Health and Human Services Department and the director of DOH-Sarasota, told the county commissioners in a July 16 email that two of the cases had been confirmed in homeless individuals.)
The state Health Department announced the first malaria case in the county in late May.
Asked about the incubation period for malaria, Brennan explained that it typically takes 14 days for the virus to build up in a mosquito to the point that it can be transmitted to a human through the mosquito’s saliva when the person is bitten. Then, he continued, it can take up to 14 days for the infected individual to start showing symptoms.
The U.S. Centers for Disease Control and Prevention (CDC) offers a slight variation on that information: “Following the infective bite by the Anopheles mosquito, a period of time (the ‘incubation period’) goes by before the first symptoms appear. The incubation period in most cases varies from 7 to 30 days. The shorter periods are observed most frequently with P. falciparum and the longer ones with P. malariae.” Those are specific types of malaria.
“We’re playing it week by week,” Brennan added during the press briefing, referring to the wait to learn whether more cases will be identified in the county.
In response to a Sarasota News Leader question, county Media Relations Officer Sara Nealeigh confirmed with Brennan that the CDC had not detected malaria in any mosquitos Brennan’s staff had sent to the agency since early June. Altogether, Nealeigh added in a July 18 email, the staff had sent 130 “malaria pools” to the CDC.
During a July 11 Facebook Live interview with Nealeigh, Brennan explained that the CDC has directed Mosquito Management Services to send one Anopheles mosquito per test tube at a time. That tube is called a “mosquito pool.”
In his July 16 email to the commissioners, Henry of Health and Human Services wrote, “Cases are identified in our local health care system and treated immediately. However, cases are not considered confirmed until the laboratory samples have been verified in the state public health laboratory and with the [CDC].”
He added, “It is important to know that the local public health response and the local mosquito control response happens immediately upon hearing of a suspect case, so our response actions do not wait for the official confirmation to act on locally identified illness.”
During the July 18 briefing, Brennan reminded the members of the news media, “Anopheles is the vector of malaria,” referring to the species of mosquito that transmits the disease. “That is our target during this situation.”
“Malaria is not transmitted from person to person. Only infected Anopheles mosquitoes can transmit malaria to humans,” DOH-Sarasota also has emphasized to the public.
Stanford Medicine’s Health Care website points out that the type of malaria that has been reported in Sarasota County — P. vivax — generally causes “less serious illness” than other types of the disease Nonetheless, the website adds that “the parasites can remain dormant in the liver for many months, causing a reappearance of symptoms months or even years later.”
“Effective treatment is readily available through hospitals and other health care providers,” the CDC notes. Individuals “with symptoms of fever, chills, sweats, nausea/vomiting, and headache should seek immediate medical attention,” the CDC stresses.
Eliminating the breeding areas and human precautions
The Anopheles breed in permanent bodies of water, such as ditches, canals and flooded wood lots with much vegetation around the edges, Brennan said.
Intermittent rain or no rain enables the Anopheles to breed easily, he suggested, while a lot of rain flushes the water body and prevents the mosquito from reproducing.
“If you have water lettuce,” he also stressed, “that’s a huge producer of Anopheles.”
An invasive species — it is not native to Florida — water lettuce floats on top of a body of water, Brennan explained; it can spread to the point that it chokes up a specific water system.
“[Water lettuce] makes a little home for them,” he said of the Anopheles. The water lettuce produces cups on which the mosquitoes can float atop the body of water, he said.
While county staff — including those in the Stormwater Division — are working to eliminate water lettuce, he pointed out, residents of private communities and homeowners can do that, as well. A firm called Florida Lake Management, which has an office in Sarasota, will send out workers to eradicate water lettuce in private communities, Brennan noted. The employees spray herbicide on the vegetation; multiple treatments are required, he added.
The herbicide cannot be sprayed on an entire pond or lake at one time, Brennan pointed out, because that would result in a loss of dissolved oxygen, which can lead to the death of forms of life in the water body.
County staff also is continuing to introduce mosquito fish — which eat the Anopheles — into water bodies. However, he explained, those fish are unable to reach the mosquitoes situated atop water lettuce cups.
Additionally, Brennan said, “We still need everybody to be vigilant about avoiding mosquito bites. This is critical.”
To eradicate the threat of malaria, he continued, humans must take precautions at the same time Mosquito Management works to kill the Anopheles.
If a person plans to be outside, Brennan said, the individual needs to wear repellent and wear long-sleeve shirts and long pants, especially between dusk and dawn, when the mosquitoes typically are most active.
DOH-Sarasota has recommended that people use mosquito repellent that contains DEET (10-30%), picaridin, oil of lemon eucalyptus, para-menthane-diol, 2-undecanone or IR3535.