Mosquito Facts

Arbovirus is short for arthropod-borne disease. Arboviruses are a large group of viruses spread by blood sucking insects. In the United States, infected mosquitoes are mostly responsible for spreading arboviruses. Birds are the main source of infection for the mosquito. Sometimes these viruses can be transmitted to horses, other animals and humans

No. Ever since the beginning of the HIV epidemic, there has been a concern that transmission could possibly occur from blood sucking insects. Studies conducted by the CDC and other institutions have proved that transmission of the HIV virus from mosquitoes or other blood sucking insects is negative.

All experiments and observations conducted observing the biting behavior of insects indicated the following: When an insect bites a person it doesn’t inject its own or previous victims’ blood into the next bird, animal or human. Instead it injects its own saliva. The saliva acts as a lubricant so the insect can feed efficiently. The HIV is fragile and can only live for a very short period outside of its environment. Therefore, its life span is short inside an insect. Also, infected people with HIV don’t have constant elevated levels of HIV present in their blood stream. The HIV level varies. Even if the virus enters a mosquito or another blood sucking insect the insect doesn’t become infected and therefore cannot transmit the HIV to the next human it bites. Insect mouth parts are small. After feeding they contain tiny amount amounts of blood particles. Normally, insects don’t travel immediately from one person to the next and feed again. They fly to a resting place to digest their meal. However, diseases like yellow fever or malaria are transmitted through certain species of mosquitoes by their saliva.

Saint Louis Encephalitis or SLE is a mosquito-transmitted viral disease. It was first recognized in St. Louis, Missouri, in 1933. Epidemics occur sporadically throughout the United States, during which several hundred people may become ill, sometimes fatally. Symptoms of SLE are similar to other viral infections and may include high fever, nausea, severe headaches and tiredness. The severity of the symptoms varies from person to person. They range from no symptoms at all to mild flu-like symptoms to severe flu-like symptoms and even death. Only 1 in 200 people who become infected with SLE virus will develop the disease. The likelihood of developing SLE symptoms is generally higher in older people.

Filariasis is a parasitic disease. It is caused by microscopic thread-like worms. It spreads from person to person by mosquito bites. When a mosquito bites a person who has lymphatic filariasis present in their blood stream the mosquito can then become infected. A person bitten by the infected mosquito can contract this disease. These worms travel to the lymph vessels and mature into adults. Here they reproduce and introduce millions of microscopic worms into the blood. On average the adult worm lives up to 7 years. This disease affects approximately 120 million people in 80 countries. These areas are the subtropical regions of Asia, Africa, Western Pacific, South America and parts of the Caribbean. This disease if not treated can lead to elephantitis.

Dengue Fever is a disease caused by four closely related viruses (DEN-1, Den-2, Den-3 or Den-4). These viruses are transmitted by the bite of an infected Aedes mosquito. The mosquito becomes infected after it bites a person who has dengue. After approximately one week an infected mosquito can transmit the virus by biting a healthy person. The symptoms are high fever, severe headache, backache, joint pains, nausea and vomiting, eye pain, and rash.

Dengue hemorrhagic fever (DHF) has the following symptoms: a fever that lasts 2-7 days along with flu-like symptoms. Infection is followed by hemorrhagic manifestations (the tendency to bruise easily, other types of skin hemorrhages, bleeding nose or gums, with hemorrhagic manifestations or possible internal bleeding). DHF is a more severe infection and if not treated can lead to circulatory system failure and shock followed by death. Mortality due to DHF is less than 1 %.

Local mosquitoes control programs and laboratories throughout the state of Florida have developed several monitoring techniques to determine the presence of Saint Louis and Eastern Equine Encephalitis (EEE). The mosquitoes that are carriers of encephalitis primarily feed on birds. One method of monitoring these viruses is by using caged chickens strategically located throughout the county. A small blood sample from each chicken is taken periodically and tested for possible presence of antibodies to SLE or EEE. If antibodies are found, this indicates the chicken has recently been exposed to encephalitis virus that was transmitted through the bite of a mosquito.

Another method some agencies use is monitoring wild birds. Because those mosquitoes may also feed on humans, there is an encephalitis risk. Another recently developed method of detecting the presence of encephalitis in wild mosquito populations involves trapping mosquitoes, grinding them up and testing for encephalitis RNA. If present, the potential exists for transmission to humans. This test is called CR (polymerase chain reaction) testing and is similar to the DNA testing used as evidence in court to tie a particular individual to a crime scene. Mosquito agencies constantly gather important data and monitor their area through their surveillance programs. The surveillance program is an important link in targeting the responsible species capable of carrying the disease. Mosquito agencies working together with the state laboratories are striving for prevention of possible epidemic outbreaks.

Because St. Louis encephalitis (SLE) and eastern equine encephalitis (EEE) can only be acquired through the bite of an infected mosquito, the simplest way to reduce disease risk is to avoid being bitten by mosquitoes. Mosquitoes are generally more active during the hours near dawn and dusk, indoor activities should be planned for those times, particularly when encephalitis alerts are given. Remember to practice good personal mosquito prevention practices as mentioned previously.

No. Saint Louis encephalitis (SLE) is transmitted to people through the bite of an infected mosquito. Being near chickens, eating eggs or chicken meat will not cause SLE, even if the chicken was infected.

In 1933 it was first isolated in the United States. It is a rare disease. Since 1964 there have been only 164 confirmed cases in the United States. EEE is found in the Caribbean, Central and South America, and North America. The majority of the cases reported in the United States occur from the eastern seaboard states, the Gulf of Mexico and a few inland Midwest regions.

This rare disease can be spread to both horses and humans by infected mosquitoes. It is in the group of the most serious mosquito-borne diseases that can affect the central nervous system and cause severe complications and possible death.

Western Equine encephalitis, St. Louis encephalitis and LaCrosse encephalitis are very similar. The life cycle of these viruses is complex. It involves a specific species of mosquito (Culiseta melanura) that lives in a marshy or swampy habitat. These mosquitoes feed only on birds. They do not feed on mammals or humans. In extremely rare cases the virus enters another habitat through other mosquitoes that feed on both birds and mammals. The virus can then be transmitted to birds, mammals and humans.

Yes, they can harm your pet dog or cat. Heartworm is caused by juvenile worms (called microfilariae) leaving the mosquito’s proboscis and being deposited on the skin of a dog or cat while the mosquito is taking a blood meal. These microfilariae find the puncture wound made by the mosquito and crawl into the animal’s bloodstream. Heartworm is a serious problem that can lead to death for the dogs and cats in Florida. However, veterinarians can prescribe medication to prevent heartworm.

According to available research, a homeowner is not in danger of contracting cancer from mosquito pesticides sprayed infrequently and at low doses by mosquito control programs. Most of the mosquito control chemicals are “non-restricted use” pesticides. This puts them in the same category as the garden and household sprays that can be purchased at the store. In fact, one common mosquito adulticide (Malathion) is a very common home and garden insecticide. Mosquito control agencies use these insecticides in much smaller doses than one might use to control larger household insect pests like the cockroach, fly or wasp.

Any person or pet that accidentally gets hit by the spray may feel a momentary slight stinging or burning sensation on the skin or in the eyes. Unless a person is very sensitive or allergic to chemicals, washing the skin with water is all that needs to be done. At the low insecticide dosage used, no other symptoms should be experienced. If other symptoms are experienced, check with a physician. The mosquito control program maintains a list of chemically sensitive persons who are called before their area is sprayed. It is the responsibility of citizens to contact their local mosquito control agency and inform them of their allergies. After providing the agency with a contact phone number they will be placed on the phone spray notification list.

The pesticides used to control adult mosquitoes have been registered by the Environmental Protection Agency and reviewed by the State Department of Agricultural and Consumer Services for use around commercial, agricultural and residential areas. These aerosol sprays are almost invisible because of their extremely small droplet size. Because of their tiny droplet size, they float in the air and therefore, usually float around objects and people. Scientific studies have shown that people standing or jogging had negligible contact with spray materials during spraying operations. Spray equipment is designed to scatter the spray material from the spray truck. Therefore, children can safely go outdoors immediately after spraying. For safety reasons they must remain a distance of 25 feet from the spray truck.

Organophosphate insecticide poisoning usually results after prolonged exposure to, misuse of, or direct contact with a concentrated pesticide product. Misuse of label instructions or accidental spillage may result in injury to an individual or contamination of water sources. Headache, nausea, vomiting, dizziness, burns, profuse sweating, and unconsciousness are some of the symptoms which may be experienced when significant poisoning has occurred. It is for this reason that an individual must know what has been sprayed. ALWAYS READ AND FOLLOW THE LABEL INSTRUCTIONS!

If poisoning is suspected or has occurred, call the poison control or seek medical advice immediately. If possible have the label with you when you call. FLORIDA POISON CONTROL CENTER at (800) 282-3171.

Though some individuals may be sensitive to some pesticides, mosquito control treatments, applied correctly, using EPA-registered products, will not harm humans or pets and are an important practice for protecting the public from mosquito-borne diseases. That said, we do offer residents the ability to be notified by email in advance before a scheduled treatment is to occur, so that these individuals can plan accordingly.