Lyme Disease and Related Tick-Borne Infections

Description

Alternative Names

Prevention

Everyone should avoid specific tick-infested areas, including tall grass, woods, and bushes where ticks tend to congregate. If this is not possible, then people should take additional preventive measures. The CDC also recommends:

• Use of tick repellant
• Routine tick checks. Removal of infected ticks within 48 hours of attachment substantially reduces the likelihood of transmission.
• Prompt antibiotic prophylaxis of tick bites. Though this method is controversial, the CDC concludes that it is probably beneficial.
• Landscaping, such as removing brush and leaf litter. This can reduce transmission rates by 50% to 90%.
• Use of pesticides to yards once or twice per year, which can decrease the number of ticks by 68% to 100%.

Protecting Property from Tick Infestation

Some of the following measures may significantly reduce the risk of tick infestation around the home:

• Mow the grass regularly.
• Clear away leaves and place wood chips as a barrier around a lawn; this has shown to reduce tick population by between 44% and 88%.

Permethrin for the Lawn. Insecticides can reduce tick infestation by 90%. Insecticides should be applied in late spring or early fall in a strip a few feet wide along the perimeter of the lawn where small animals are likely to enter or live.

The most commonly used insecticides are pyrethrins, which are compounds derived from the Chrysanthemum family. They are available as natural products or in synthetic forms (permethrin). They are poisons that affect the nerve system of insects. They are safe, particularly the natural products, for humans and pets. All pyrethrins are highly toxic for certain fish and slightly toxic for birds, such as mallard ducks. Some people do experience an allergic reaction to them. As with all insecticides, there is some concern about the possible consequences of long-term exposure, but to date there is no evidence of any harm.

Damminix, available in hardware stores, consists of cardboard tubes stuffed with permethrin-treated cotton. The tubes are placed where mice can find them (e.g., dense, dark brush) and collect the cotton for lining their nests. The pesticide on the cotton kills any immature ticks that are feeding on the mice. Best results are obtained with regular applications early in the spring and again in late summer. As many neighbors as possible should use it to be effective. (It is not effective on the West Coast.)

Other Pesticides. Other tick-killing spray pesticides that have been used include those containing diazinon, chlorpyrifos, and carbaryl. Animal studies have reported severe toxic effects associated with these chemicals. Some of these agents in fact are being phased out for home use. Parents should balance the effects of a very negligible risk for a highly treatable infection versus excessive use of possibly harmful chemicals.

Eliminating Risk from Deer

Fencing. Deer fence, which is a wire fence about three to four yards high, or electrified fencing can be helpful but it is costly to put up and maintain.

Ivermectin. Corn that is laced with ivermectin (Ivomec and others) and then eaten by deer helps prevent ticks from feeding on them. It should be noted that ivermectin is present in a number of product used by veterinarians to control parasites, such as heartworm. It has potential toxic effects in collie or collie mixed breeds, however.

Protective Clothing in the Woods

Hiking and camping in the Northeastern woods carries a significant risk for tick bites and Lyme disease (3% in one study). Anyone out in the woods during tick season should wear protective clothing, including the following:

• Light-colored clothing. (This makes it easier to spot ticks.)
• Long-sleeved shirts and long pants with cuffs tucked into shoes or socks.
• High boots, preferably rubber boots.
• Tick-collars made for small dogs can be worn around the ankles over socks or pants.

Simply washing clothes will not kill ticks. After venturing outdoors, people should run their clothes through a dryer at high temperature for a half hour. Spraying clothes with solutions containing permethrin (Permanone, Duranon, Permakill) affords additional protection. Keep in mind that these sprays should not be applied to the skin. Clothes should not be retreated with permethrin for 48 hours unless they are washed.

Insect Repellent

DEET. Most insect repellents contain the chemical DEET (N,N-diethyl-meta-toluamide), which remains the gold standard of currently available mosquito and tick repellents. Comparison studies suggest that DEET preparations are the most effective insect repellants now available. Concentrations range from 5% to almost 100%. DEET has been used for more than 40 years and is safe for even most children when used as directed.

Experts recommend that most adults and children over 12 years old use preparations containing a DEET concentration of 20% to 35% (e.g., Ultrathon), which provides complete protection for an average of five hours. (Higher DEET concentrations may be necessary for adults who are in high-risk regions for prolonged periods.) A concentration of 10% or less is recommended for children ages two to 12. In general, infants under 12 months should use non-DEET repellents, such as soybean-based Bite Blocker. Some experts believe low DEET concentrations are safe even in infants over two months old. Parents traveling to or living in high-risk areas should check with their physician.

It should be stressed that the effectiveness of DEET varies from individual to individual and depends on climate changes. For example, it can be washed off during swimming or by rain. High temperatures make it less effective. DEET, particularly in very high concentrations, can also dissolve plastics, including those used in glasses and watches and some synthetic clothing. DEET should not be put on clothing.

Overexposure to DEET at any age has produced toxic effects, including itching and rash and, in severe cases, irritability, insomnia, and confusion. It should be noted, however, that it has been intensively studied for 40 years and used in billions of applications. Only 50 such toxic reactions have been reported, and most of them resolved without any consequences.

When applying DEET, the following precautions should be taken:

• Do not use on the face and apply only enough to cover exposed skin on other areas.
• Do not over apply and do not use under clothing.
• Do not apply over any cuts, wounds, or irritated skin.
• Parents or an adult should apply repellent to a child and not let the child apply it him- or herself. They should first put DEET on their own hands and then apply it to the child. They should avoid putting DEET not only near the child's eyes and mouth, but also on the hands (since children frequently touch their faces).
• Wash any treated skin after going back inside.
• If using a spray, apply DEET outdoors--never indoors. Spray repellents should not be applied inside or directly on anyone's face.

Self-Inspection and Tick Removal

Self-Inspection. The tick is unlikely to transmit the infection within three days of the bite, but prompt removal is still important. The following tips are important for self-inspection:

• Ticks responsible for Lyme disease are very small and may resemble freckles or scabs.
• People spending time in tick-infested locations should inspect themselves several times a day, including at bedtime.
• Check nonexposed areas, such as the back of the knee, as well as exposed areas. Someone else should check the scalp, back of the neck, and other difficult to reach areas.
• Check clothing as well as skin. A tick on can be hidden in folds or creases.

Tick Removal. If an attached tick is discovered, there is no reason to panic. Do not put a hot match to the tick or try to smother it with petroleum jelly, nail polish, or other noxious substances. This only prolongs exposure time and may cause the tick to eject the Lyme organism into the body.

The safest and most effective way to remove an attached tick is the following:

• Grasp the ticks mouth area with clean tweezers as close to the skin as possible. (Take care not to handle it with bare fingers as this can also spread infection.)
• Next, pull upward with a steady even pressure. Do not twist, crush, or squeeze the body area of the tick, because this region contains the infectious agent. In fact, do not be alarmed if some of the mouth parts remain in the skin. They are not infectious.
• Put the tick in a jar or container of alcohol, which will kill it. Some people lay a piece of adhesive tape to the top of the tick and fold it over, without touching the insect. Then they simply throw it away. Tape is also effective for trapping a tick that has not yet attached to the skin.
• Once the tick is removed, wash the bite area with soap and water or with an antiseptic to destroy any contaminating microorganisms. Wash hands as well.

Vaccines

The LYMErix Vaccine. The LYMErix vaccine, previously approved, was taken off the market because of poor sales and because of problems encountered with its use. A primary limitation is that the vaccine was effective only in about 75% of cases and the effects are not long lasting. Unfortunately, were concerns as well, notably reports of arthritic and neurologic symptoms in a few vaccinated people. There is no evidence at this time that the vaccine was responsible for these symptoms. In fact, a 2002 study based on the major government vaccine reporting system of 1,400,000 doses reported no unusual adverse side effects, although there was a higher risk for allergic reactions than expected. It should be noted, however, that most patients do not report their symptoms to this system.

Other Vaccines. Two promising experimental vaccines designed to target all B. burgdorferi are showing promise and could become available by 2004. (At this time, for patients at high risk after a tick bite, the best approach may be a one-dose antibiotic within 72 hours of the bite.)

Protecting Pets

Since dogs, cats and even horses can get Lyme disease, pets should be inspected for ticks regularly. Symptoms in animals include lameness and lethargy. Dogs are much more likely to get Lyme disease than cats, but both are susceptible. In dogs, symptoms occur two to five months after a tick bite and include fever, lameness, and lack of appetite. In rare cases, it can cause kidney damage if it is untreated.

Preventive Products. Products containing permethrin (Bio Spot, EXspot), amitraz (Preventic), or fipronyl (Frontline) can be used safely on dogs. Not all of these products are safe in cats. And, only permethrin is also effective against fleas. Some veterinarians suggest that the combination of BioSpot and Preventic is very effective. (Another product--selamectin [Revolution]--is sold for flea and tick control, but it appears to have very limited effect against ticks.)

Vaccines. Lyme disease vaccines are available for dogs, but they do not offer total protection. Veterinarians vary in their use of the vaccines.

Treatment. As in people, antibiotics almost always cure the infection in animals.