Fear of Pesticides Thwarts Lyme Disease Prevention Effort


Fear of Pesticides Thwarts Lyme Disease Prevention Effort

"HEALTH NUT SO SCARED OF FOOD ADDITIVES...HE STARVES TO DEATH" was the title of an article published recently in a supermarket tabloid. The deceased had eliminated more and more foods from his diet as he became increasingly fearful of "chickens and turkeys pumped full of chemicals" and "insecticides sprayed on fruits and vegetables."

While this story of chemophobia taken to the farthest extreme seems incredible, equally unjustified fear of pesticides drives Americans to make all sorts of irrational choices that endanger their health and the health of their children. One recent example is the refusal of suburban residents in the part of the country with the highest incidence of Lyme disease to even consider using pesticides to combat disease-carrying ticks. While pesticides are no guarantee against contracting the disease, in certain areas of the Northeast their use can greatly reduce Lyme disease risk.

Lyme Disease has Serious Consequences

Lyme disease is caused by a bacteria, Borrelia burgdorferi which is transferred to humans via a tick (lxodes) bite. Infection is most commonly acquired from nymphal ticks between May and July. Occasionally, adult ticks transfer the bacteria in the fall and spring. But bites can occur at any time during the year.

Antibiotic treatment for Lyme disease exists. But because Lyme disease is hard to diagnose, and people often don't know they have been bitten, early treatment is not always possible. Without early treatment, Lyme disease can have serious consequences affecting the skin, nervous system, heart and joints. Delayed treatment can lead to cardiac and neurologic abnormalities and chronic arthritis. Therefore, preventing the infection is always preferable to treatment after infection.

High Incidence Demands Action

Lyme disease is the most frequently reported arthropod borne disease in the U.S.; 40,108 cases were reported between 1982 and 1991. While cases occur throughout the country, and throughout the world, they are concentrated primarily in the Northeast and parts of the Midwest, where a large percentage of ticks are infected with B. burgdorferi.

New York has more Lyme disease cases than any other state, accounting for 56 percent of the total cases in 1988. Westchester County is the most seriously affected, with nearly one fourth of all reported cases. Between 1986 and 1991, New York State had a sevenfold increase in cases. The number of cases continues to increase as the population of infected ticks expands in number and range. Many Lyme disease cases in the highly affected parts of New York occur in children; 39 percent are under ten years of age.

The highest risk of exposure in the Westchester area is on residential properties and their surrounding areas. One study reported that 36 to 60 percent of properties surveyed had infected nymphal and adult ticks capable of transferring disease. In an investigation of the possible cause of 11 Lyme disease cases in Westchester, in all but one case infected ticks were found on or near the well-maintained lawns or in the vicinity of the residence of the patient. This suggests that the disease may be acquired at home during routine outdoor activities like recreation, gardening or lawn maintenance.

An Effective Answer

The high percentage of infected ticks on lawns and the borders surrounding lawns make pesticide application an effective measure against the disease.

A single pesticide application can significantly reduce the number of ticks on residential lawns. Three pesticides have been found effective to reduce ticks 70 to 97 percent in a single application: carbaryl and chlorpyrifos (both available in your local garden shop) and cyfluthrin (available from lawn care professionals). After application, the number of nymphs remained low through the transmission season. Two applications during the year would eliminate most ticks, one spray at the end of May to rid the area of nymphs, and another in late September to kill any remaining adults.

Chemophobia Thwarts Preventive Efforts

Information regarding these effective pesticides was made available to the public and local health departments in June 1991, but it was met with great reluctance. Dr. Durland Fish, an entomologist with New York Medical College and the author of studies demonstrating the effectiveness of pesticide use in reducing tick infestation, reports that, "More than one individual has told me that they would rather have Lyme disease than apply carbaryl to their lawn."

The reaction of the Westchester County Health Department has not been much better. They will not recommend insecticide use for reducing the risk of Lyme disease. In fact, New York, the state with the most Lyme Disease cases, was the last state in the nation to approve cyfluthrin for lawn application. It still has not approved a permethrin-based tick repellent available in all other states with Lyme disease. But Dr. Fish maintains, "Since alternatives to spraying are either ineffective or unavailable, the prudent course of action is for homeowners to apply lawn insecticide.

Similarly, exposure occurs in public parks. But, widespread pesticide application in parks would be expensive and is in most cases unnecessary. Spraying in high use areas, such as around popular trails and picnic areas would help reduce human contact with ticks.

Kenneth B. Leigner, a physician from Armonk, NY who tried to alert his son's school of the need for pesticides to reduce tick populations, stated, "The longer I am involved in caring for patients with Lyme disease the stronger is my willingness to argue for maximal protection for all persons against deer tick exposure." The doctor has seen cases of Lyme disease in children he believes were due to unnoticed tick bites that occurred during sporting events on school playing fields. His opinions were not popular with the majority of parents at the school who had strong feelings against pesticide use.

Pesticide Safety

By definition, pesticides must be toxic to work. Consequently, common misunderstandings about toxicity fuel an unjustified fear of pesticides. But, just because a substance is toxic to an insect does not mean it is toxic to humans. Studies show that different species have different susceptibilities to substances. Modern pesticides, including those that are effective for killing ticks that carry Lyme disease, are relatively specific in their toxic effects. Toxicity also depends on the dose. The tremendous difference in body weight between insects and larger animals or humans provides further safety.

Carbaryl, chlorpyrifos and cyfluthrin (see sidebar) have all undergone tests for longterm and acute (the ability to cause damage with a single relatively large exposure) toxicity, and have been registered by the Environmental Protection Agency as safe when used according to the directions on their labels.

Awareness and Vigilance Still Required

The health departments in tick-infested areas suggest that people try to avoid tick habitats, including wooded areas, surrounding fields and lawns. They recommending that people wear protective clothing and use a repellent. After visiting these areas, people should carefully examine themselves and their children for ticks. Common places for tick bites are the lower legs, backs of knees, groin, armpits, neck and back. Because ticks must remain attached to the skin for close to 48 hours for Lyme disease to be passed, their removal before this time will reduce the chance of infection.

However, recent studies in New York and New Jersey report that up to 60 percent of people who contract Lyme disease do not remember being bitten by a tick. Furthermore, if people live in areas that are favorable tick habitats, exposure is hard to avoid. Therefore, the use of safe and effective pesticides, which have been proven to eliminate ticks, can be an important line of defense in Lyme disease prevention. But remember, spraying, while effective for children and pets restricted to your own yard, will not help you avoid ticks in other areas.

The identification of the bacterial cause and arthropod carrier of Lyme disease has enabled researchers to investigate disease prevention methods. Pesticides are being identified that can significantly reduce the tick population that transfers the disease in residential areas. But this research may be in vain if people, injustifiably fearful of pesticides, would rather chance the serious effects of Lyme disease than apply pesticides which when used in the approved regulated manner are safe and effective.

American Council on Science and Health, Inc.


By Andrea Golaine

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Therefore, the use of safe and effective pesticides, which have been proven to eliminate ticks, can be an important line of defense in Lyme disease prevention.