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West Nile Virus by  by  HEAL of S AZ members–

from HEAL of Southern Arizona’s newsletter Ecologic News Spring 2003


Birds infected with West Nile Virus (WNV) could reach Arizona sometime this year, along with the possibility of mosquitoes transferring the disease to humans. Most infected people do not become seriously ill but in rare cases death can result. Communities across the country are involved in mosquito abatement programs to prevent WNV and other mosquito-borne illnesses. Because the MCS community is especially sensitive to pesticides, HEAL of Southern Arizona is investigating the possibility of spraying in Pima County and other parts of Arizona.


According to officials at the Pima County Health Department: (1) Most affected communities have not had to spray for adult mosquitoes and it is unlikely that Pima County neighborhoods will be sprayed. (2) The CDC recommends spraying for adult mosquitoes in residential neighborhoods only if there are a large number of human cases and actual deaths [there were a total of 4,156 reported cases of WNV in the US in 2002, resulting in 284 deaths in 26 states].  (3) If that were the case here, only affected neighborhoods would be sprayed, and residents would be given notice. (4) The Department will continue to rely on larvicide and the reduction of mosquito breeding grounds.

The MCS Awareness Week meeting on May 9th will feature speakers from the Health Department promoting its “Fight the Bite” campaign, in order to educate the public about the importance of removing mosquito breeding sites around residences. This will also give us an opportunity to present information on the harmful effects of pesticides on people, pets, and the environment, and to voice our group’s special concerns.


West Nile Virus is coming! Can spraying be far behind?

By HEAL member  (From HEAL of Southern Arizona’s Newsletter Ecologic News, Fall 2002)


Birds carrying West Nile Virus (WNV) are spreading westward across the country, bringing with them concern that mosquitoes will become infected and transmit the disease to humans. How dangerous is WNV? The New York Department of Health says that even in infected areas, very few mosquitoes are infected – much less than 1%. And less than 1% of people bitten by infected mosquitoes become seriously ill. According to the Pima County Health Department, 160 people in the U.S. have died from WNV this year. In comparison, about 20,000 people in the U.S. die from influenza every year.

The Environmental Protection Agency (EPA) and the Centers for Disease Control (CDC) recommend controlling mosquitoes with an Integrated Pest Management (IPM) approach, which relies largely on source reduction and killing larvae before they become adults. However, many citizens think that widespread pesticide spraying will help protect them from WNV, and many communities in affected areas are spraying in response to public demand. This poses problems for the population in general, but especially for chemically sensitive people.  


Ariel Barfield, Alice Garay, Lauren McElroy, Madeline Rivera, Pam Ruggles, and Gayle Sumida have been contacting officials to obtain information and express our concerns about pesticides


Mosquitos are the “vectors” for West Nile Virus and birds the "reservoir." WNV was first identified in 1937 in Uganda, and is widespread and common throughout Africa, Central Asia, and Europe. The closest match to the WNV strain now in the US comes from Israel. Birds in Africa, Asia and Europe do not become ill from the virus -- they have been immune for generations. 


The fatality rate for infected horses in the U.S. is 35%. Killed virus inoculations are available from veterinarians for horses, mules, donkeys, and their relatives. Dogs and cats seem not to get the virus.

An infected bird may be off balance (ataxia), circling, and have tremors and an abnormal head posture. Some birds can be infected and infectious for five days before they show illness. Pacific Flyway migratory birds are carrying WNV north, south, and west. The drought is resulting in bird populations that are concentrated near the few remaining water sources, where the mosquito populations are also concentrated.

Chickens do not get sick, but do create detectable antibodies, which make them ideal for detecting viruses in the bird population. “Sentinel” chicken groups in Arizona are tested every two weeks for WNV.  


Children with active West Nile Fever have rash, aches and fever. Adults, especially the elderly and those who are immune compromised, may have headache, fever, swollen glands, sore throat, "flu," disorientation, and confusion. Clinics are to report any encephalitis patient to the state, and submit a blood sample, with follow-up sampling in 15 days. The St. Louis Encephalitis (SLE) virus produces antibodies that are not at first readily distinguished from West Nile Virus antibodies in humans. 


Adult female mosquitoes breed in standing water and live two to four weeks. Mosquito season in Southern Arizona is 9-12 months per year. Freezes in the north and at high altitudes will help, but may not kill all mosquitoes. Culex is the most common type of mosquito to carry WNV. Culex mosquitoes generally do not move far from their larval habitat. They start biting around dusk then continue all night. 


A joint statement by the EPA and CDC says, “The underlying philosophy of mosquito control is based on the fact that the greatest control impact on mosquito populations will occur when they are concentrated, immobile and accessible. This emphasis focuses on habitat management and controlling the immature stages before the mosquitoes emerge as adults. This policy reduces the need for widespread pesticide application in urban areas.”

Eliminating standing water is the most effective way to reduce mosquito populations. Since mosquitoes can breed in any puddle that lasts more than four days, it is important to empty wading pools, clogged ditches, rain water trapped in old tires, wheel barrels, garbage cans, etc.

The second most effective way to eliminate mosquitoes is to treat pools of standing water with larvicides (agents that the kill mosquito larvae). Larvicide agents include vegetable or mineral oil, insect growth regulators such as methoprene, bacteria such as BTI (Bacillus Thuringensis Isrealensis) and BS (Bacillus Sphaericus), and fish that eat larvae. BTI is readily available in a product called Mosquito Dunks. While BTI and BS are not toxic to mammals, they may be harmful to non-target insects and mosquito predators. 


The application of pesticide intended to kill adult mosquitoes is called “adulticiding.” According to the EPA and CDC, this is the least effective mosquito control technique. In order to kill an adult mosquito with pesticide spray, there must be direct contact with the droplet. Since mosquitoes hide in places where the spray does not reach, adulticiding is not very efficient.  


The adulticides commonly employed in mosquito abatement programs are called SCOURGE (resmethrin and piperonyl butoxide), ANVIL (sumithrin and piperonyl butoxide), AQUA-RESLIN (permethrin and piperonyl butoxide), and FYFANON (malathion).

Resmethrin, sumithrin, and permethrin are pyrethroids -- synthetic broad-spectrum insecticides that are neurotoxic (harmful to the nervous system). Symptoms of pyrethroid exposure include coughing, wheezing, chest pain, stuffy nose, breathing difficulties, nausea, headache, and incoordination. Pyrethroid poisoning can cause convulsions, and death due to respiratory failure. These chemicals can also disrupt the endocrine system, mimicking the effects of estrogen. Such disruption can lower the sperm count in men and cause the growth of abnormal breast cells. People who are allergic to ragweed are often sensitive to pyrethroids.

Piperonyl butoxide (PBO) is a synergist -- it increases the potency of the pesticide and inhibits the body’s ability to detoxify chemicals. The EPA has classified PBO as a possible human carcinogen (cancer causer).

Malathion (FYFANON) is an organophosphate pesticide. The organophosphates are extremely toxic to public health and the environment. They affect the central nervous system, cardiovascular and respiratory systems. Organophosphate exposure can also cause chromosome damage, gastrointestinal disorders, and weakening of the immune system. Other organophosphates employed in mosquito abatement include naled (DIBROM) and chlorpyrifos (MOSQUITOMIST). Symptoms of organophosphate exposure include numbness, headache, dizziness, tremors, nausea, sweating, and incoordination. Organophosphates can also cause breathing difficulty, blurred vision, unconsciousness, and convulsions that may lead to death. Malathion has been linked to the development of multiple sclerosis (MS).

The Albany Times Union told about a mosquito abatement program in New York involving the pesticide ANVIL during the year 2000. According to the article, more people reported symptoms from the pesticide than from West Nile Virus.

According to a Washington Times article, Washington, D.C. has been using larvicide since April 2002, but no adulticide has been used so far. The article quotes Peggy Keller, chief of the District’s Animal Disease Prevention Division, saying, “Statistics indicate that larviciding works better because spraying can be problematic for people with respiratory problems.”

In addition to putting people at risk, wide area mosquito spraying kills beneficial non-target insects, such as bees and ladybugs. It also kills mosquito predators, such as dragonflies and damselflies, and reduces the food supply for frogs, bats, and fish. Furthermore, overuse of pesticides can cause insect species to become pesticide resistant. 


At this time, the virus has been confirmed in New Mexico and Colorado and it is expected in Arizona by next summer at the latest. According to a State WNV briefing, FYFANON and ANVIL are already being sprayed between midnight and 5 A.M. in Gilbert and elsewhere in Maricopa County.  


There is no widespread spraying for mosquitoes in Pima County at this time. Bruce Prior is a City of Tucson Water Department hydrologist involved with the mosquito abatement program at the Sweetwater Wetlands area. Prior says larvicide is applied weekly, and adulticide is also used at certain times of the year.

According to Prior, the larvicide BTI is sprinkled over the Wetlands from a remote control helicopter on Friday mornings. The larvicide BS is also applied periodically.

Aerial spraying with the adulticide ANVIL is done over the Sweetwater Wetlands in the spring and fall when the migratory birds arrive, or when the mosquito count exceeds a certain level, says Prior. Spraying is done up to twice a week, if it is not too windy. Periodic aerial spraying over the Wetlands started in September 1999 to keep out encephalitis strains that are also carried by mosquitoes and brought in by the migrating birds. MALATHION was used when the program first started, but the neighbors complained about the smell, so they switched to Anvil. Prior says that Anvil is safer than malathion. He doesn't think it affects the butterflies or the birds. Prior can be reached at the City of Tucson Water Department at 791-5080 x1403.

Barbara Johnson, at the Disease Control Office of the Pima County Health Department, 740-8261, thinks the public will expect adulticide spraying when WNV gets here. Whether or not the county actually does spray will depend on the severity of the outbreak. According to Johnson, the first year after WNV arrives will be the worst, because many people and animals will become immune to the virus. When asked if people can request prior notification about spraying, Johnson replied, “the newspapers will surely tell people ahead of time.” 


Some communities are using mosquito control methods that are more effective and less hazardous than pesticide spraying. Can we persuade Arizona leaders to take an enlightened approach? HEAL of Southern Arizona is gathering information and trying to come up with a plan of action. We could use some help with this project. Would you like to be involved? Do you know people with decision-making authority that we should contact? Call Ariel at 327-4679 or Madeline at 297-7992 if you can help.

In the meantime, the Pima County Health Department says if you are concerned about mosquito control, you can contact: Consumer Health & Food Safety, 150 W Congress, Tucson AZ 85701. 


Be aware that scented products attract insects. Mosquito bites can be avoided by keeping window and door screens in good repair, and staying indoors at dawn and dusk. If you must be outside during this time, wear long pants and long-sleeved clothing. Government agencies recommend applying insect repellents containing up to 35% DEET, but these are toxic products that should be avoided by the chemically sensitive. Alternative mosquito repellents are available, but they do not work as well as DEET.

Stuart Lanson, M.D., a physician who specializes in environmental illness, advises his patients to take 100 mg of Thiamin (Vitamin B1) twice a day, to help repel mosquitoes. Dr. Lanson also recommends taking herb Olive Leaf, which contains a virus killing agent called oleuropein.

The Chemical Sensitivity Service and Support Group of Phoenix passed on the following tip from a gardening club: Put some water in a white dinner plate and add a couple of drops of Lemon Fresh Joy dish-washing soap. Set the dish on a porch or patio. Mosquitoes are attracted to the dish and tend to leave nearby people alone. 





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