December 2002 Mosquito Control - Why? On many occasions, usually after the noisy spray trucks or low flying has gone by spewing a foul smelling pesticide cloud, I’ve heard the statement, “What do we need mosquito control for? I’m not bothered by mosquitoes!” Here in lies the crux of the matter, when Mosquito Control Agencies do their job well the perception is that mosquito control is not needed. Mosquitoes are a weather dependent, biological entity - control efforts have to be proactive. If you wait and react after the problems occur, it’s too late, the disease, annoyance or economic loss has already occurred.
Mosquito Control in Florida started before Florida was Florida. The Spanish, French and English explorers told tales of mosquitoes in such abundance that they were forced to sleep on the beach covered with sand. In the 1870's and 1880's outbreaks of Yellow Fever in the Panhandle, Jacksonville, Key West, Tampa, Plant City and Manatee County took a tremendous toll in human suffering and death. In Jacksonville, with a population of 26,800, the 1888 epidemic killed 400, sickened 5,000, and caused 10,000 to flee the city. Of the 16,000 remaining, 14,000 were left unemployed as a result of the breakdown of commerce. If you ever visit St. Augustine, take a look at the headstones in the old cemetery in the middle of the city, most of the poor souls there met their maker because of yellow fever.
Malaria, a disease caused by parasitic protozoans, was a major impediment to the development of Florida. Between 1917 and 1930, 33 of the 67 counties, half of Florida, had annual malarial death rates of one person per 1,000 population or greater. Prior to source reduction efforts during the 1930's and 1940's, malaria was a major problem in Florida. An example of malaria’s effect was in Perry, Florida where the main industry was lumbering. During the summer the industry would shutdown, hence the area’s economy, because half of the town’s population was sick with malaria and unable to work. Presently, worldwide, there are 400-500 million cases of malaria annually with at least 2 million fatalities. This disease is not declining but is becoming a growing international problem. Despite the decline of malarial transmission in North America, dozens of Florida residents pick up the disease from overseas every year, providing an opportunity for local mosquitoes to become infected and transmit the disease. Fortunately, Florida, like the rest of the United States, has excellent health and medical systems to diagnose and treat infected individuals before the disease can be spread to others.
Dengue, a mosquito-borne viral disease with symptoms ranging from a simple flu-like illness to severe hemorrhagic symptoms, shock, encephalitis, and even death, is a major problem in the Caribbean, Central, and South America, with hundreds of thousands of cases occurring annually. The two mosquito species that transmit this disease are both very common in Florida. Although dengue transmission has not been documented within Florida in recent years, this disease had a major impact during the early development of the state. Dengue was first noticed in Florida in 1850 and by 1934 an epidemic of over 15,000 cases occurred in Miami.
St. Louis Encephalitis (SLE) is a virus that is endemic to Florida that infects wild birds. There are several species of mosquitoes in Florida that can pick up the disease from birds and transmit it to humans. Since the late 1950's, SLE has become the predominate mosquito-borne disease of humans in Florida. Epidemics reoccur in the south and central portion of the state. Major epidemics occurred in 1959, 1961, 1962, 1977 and 1990. During the 1959-1962 outbreak in the Tampa Bay area, 55 fatalities occurred amongst 315 cases. The largest, single year epidemic occurred in 1990 in 28 counties with 223 cases and 11 fatalities. Such epidemics result in considerable disruption of normal activities of permanent residents, not to mention their effect on tourism. Economic loss to the state has not been well documented but the 1990 epidemic alone was responsible for million of dollars of direct costs (cancelled events and medical care) and indirect costs (tourism and lost work time).
Eastern Equine Encephalomyelitis (EEE) is also a viral bird disease and a permanent resident in Florida. EEE is a disease that is usually fatal in man, horses, and other equines. Horses and people who survive the disease usually have some level of permanent neurological impairment. A study done in Massachusetts on the cost to care for a human survivor of this disease is about $3,000,000 over the individual’s lifetime. Fortunately, epidemics of EEE are rare in Florida; most human cases are isolated and few in number, usually only one or two per year.
West Nile Virus (WNV) is the new player in Florida. This virus is also a bird disease that can cause mild or severe disease in birds, humans, horses, dogs, alligators, squirrels and the list is growing. Data on this disease is on going at this point, the disease is still settling in... so to speak, its potential effects are still unknown. The one thing that is known is that it is going to cost a lot of research dollars to understand this virus and its ultimate effect on man and his animals.
Dog Heartworm is a chronic parasitic disease of dogs and sometimes cats. The filarial worm parasite is transmitted by mosquitoes from dog to dog. The mature worms live in the canine heart. Untreated, the worms eventually clog the heart and kill the dog. Prevention and management of heartworm in dogs is best accomplished with available pharmaceuticals. The veterinary cost of this parasitic disease is in the hundreds of millions of dollars annually.
The stories and historical events of mosquitoes and their effect on people, animals, the development of Florida and for that matter, the world, are endless. Historically, Florida has suffered from repeated epidemics of serious mosquito-borne disease, including yellow fever, malaria, dengue, and encephalitis. These diseases remain a serious threat to Florida residents and visitors. Florida’s proximity to the Caribbean basin, which is currently suffering from these diseases, is reason for concern about the resurgence in our state. In the past 35 years, St. Louis Encephalitis, Eastern Equine Encephalitis, and West Nile Virus have become increasing important in Florida. The reasons for mosquito control are obvious... nuisance, health and economic welfare. Without mosquito control, Florida would be a miserable place to live just because of their biting. When you factor in the direct cost of disease, health care, disability and death caused by mosquitoes and the indirect costs of lost productivity, cancelled events, and lost tourist dollars, a good mosquito control program is not only essential, it is a bargain. Though poorly documented, the economic costs associated with mosquito-borne disease are probably growing rather than subsiding as development of the state progresses and the population increases. Like other things we take for granted, such as central water, sewage disposal, educational facilities, transportation systems, communication systems, electricity, medical facilities, and emergency services, mosquito control is a necessary part of our society’s infrastructure. |