Photo courtesy CENTER FOR DISEASE CONTROL/JAMES GATHANY
This 2006 photograph depicts a female Aedes aegypti mosquito in the process of acquiring a blood meal from her human host, who in this instance, was actually the biomedical photographer, James Gathany, at the Centers for Disease Control. Aedes aegypti, aka the yellow-fever mosquito, is one of two species commonly found in Pinellas County.
ST. PETERSBURG – Pinellas County officials announced Jan. 16 that one of its sentinel chickens had tested positive for Eastern Equine Encephalitis.
Pinellas County Mosquito Control received results Jan. 14 confirming that a sentinel chicken had tested positive at Sawgrass Lake Park in St. Petersburg, according to a press release.
The county’s sentinel chickens are part of a statewide network that serves as an early detection system for mosquito-borne arboviral diseases. The chickens located in eight locations around Pinellas are tested weekly. A positive result from the routine blood tests alerts officials that a virus is present in the local area.
According to the Centers for Disease Control and Prevention, eastern equine encephalitis virus (EEEV) is transmitted to humans by the bite of an infected mosquito. Eastern equine encephalitis (EEE) is rare in humans, and only a few cases are reported in the United States each year. Most people show no symptoms.
Symptoms of encephalitis, an inflammation of the brain, usually begin with a sudden headache, and include high fever, chills and vomiting. There is no specific treatment. People who suspect they may have EEE should consult a healthcare provider.
The public can reduce the likelihood of getting EEE by avoiding mosquito bites. Health officials recommend the use of insect repellent that contains DEET, picaridin and oil of lemon-eucalyptus. Officials advise the public to read labels before purchasing and using any repellant. Some are not recommended for children under age 3. Repellant should be sprayed on exposed skin and clothing, but not under clothing.
Wearing protection clothing – loose fitting clothing that covers the arms and legs – also is advised. Light colors are best. Staying indoors when mosquitos are most active, usually around dusk and dawn, also should reduce the likelihood of being bitten by an infected mosquito.
Mosquito Control technicians routinely treat known breeding areas by ground and by air, as well as responding to requests from residents.
Most people associate mosquitos with summer; however, county officials point out that recent rains have increased the local mosquito population. The public can help reduce the population by removing the breeding grounds around homes and businesses.
Mosquitos can breed in as little as a quarter-inch of standing water. Residents are advised to remove as many sources of standing water as possible. Mosquito control advises residents to take the following precautions:
• Empty water from old tires, flowerpots, garbage can lids, recycling containers, boat tarps and buckets. Eliminate standing water near plumbing drains, air conditioner drips, septic tanks or rain gutters.
• Flush birdbaths and wading pools weekly. Flush bromeliads twice weekly or treat with a biological larvicide.
• Change the water in outdoor pet dishes daily.
• Keep pools adequately chlorinated.
• Stock ornamental ponds with mosquito-eating gambusia fish.
• Cover rain barrels with fine mesh screening.
• Repair rips or tears in door and window screens.
• Clean gutters and other areas of leaves and other debris.
Florida is home to 80 species of mosquitos, according to an article written by Jorge R. Rey, a professor at the University of Florida. He describes them as one of the “most versatile organisms on earth.
“ They can reproduce in virtually any natural or man-made deposit of water …,” he writes in an article published by the Entomology and Nematology Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida.
Professor Rey explains that the mosquito life cycle begins with the egg stage, when the females lay their eggs in “any water-holding area,” such as tree holes, ponds, puddles, ditches, and artificial containers including old tires, planters, buckets and more.
Hatchlings, called larvae, grow into pupae from which the adults emerge. Males usually emerge first and remain around the breeding site, waiting for the females, Rey writes.
“ … it is only the female that will seek a blood meal, which most species need in order to develop their eggs,” he says.
Rey also says female mosquitos lay batches of eggs during their three-week to five-month life span. For some species, each batch requires a blood meal.
This blood meal, most usually referred to as a bite, is more accurately described as a sting, according to Rey. During the blood-sucking process, the mosquito injects a small amount of saliva, which is the cause of swelling and itching. It is through the saliva of an infected mosquito that diseases such as West Nile virus, St. Louis encephalitis and canine heartworm are spread.
Pinellas County is home to two types of mosquitos that experts refer to as “ankle-biters” because they most often take their blood meal below the knee. They are tenacious feeders, flying away at any movement, only to return repeatedly until they get a meal. Experts say that behavior often makes one mosquito appear like more.
Professor Rey concludes his article by debunking several mosquito myths.
He says while bug zappers are effective against mosquitos, they do not control them and can be harmful to populations of beneficial insects. He advises that electronic "repellers" are a waste of money.
Mosquitos do not nest, so they cannot nest in vegetative areas. Vegetative areas without standing water are not home to breeding mosquitos.
Birds, bats, owls and other birds do eat mosquitos but not enough to serve as a control method.
He says claims that spraying adult mosquitos is best are wrong. Eliminating the insect before the adult stage is better.
Claims that the plant citrosa repels mosquitos also aren’t true, Rey says. Citronella oil is used as a repellant, but the undisturbed plant does not release oil and thus cannot repel.
More information on controlling mosquitoes and a mosquito control request form can be found at www.pinellascounty.org/mosquito or residents can call Pinellas County Mosquito Control at 464-7503.