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Monday, 16 August 2010 14:40

“Doc - You Say That A Killer Might Be Lurking In My Backyard?!”

Written by  A.J. Neumann, D.V.M.
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In most areas of the United States the killer will be in your backyard and, if not, you can almost bet he can be found hiding in the “back forty.”

In the mid 1970s, Lyme disease was first recognized in the northeastern town of Lyme, Connecticut. It was found to be the cause of a large number of cases of rheumatoid arthritis which was occurring in children living in the area. Since that time it has become the most common vector-borne disease of human beings in the United States. This infectious disease also affects countless numbers of our domesticated animals such as cats, dogs, cattle and horses. While case numbers are not available for the animals, about 24,000 human cases were reported to the Center for Disease Control and Prevention in 2005. This number is three times greater than those reported in 1993. Recent studies reveal that the actual number of human Lyme disease cases could be over 200,000 per year.

Lyme disease is acquired by transmission of the spirochete Borrelia burgdorferi, through the bite of an infected tick. The Black-legged tick (often mistaken for the Deer tick simply because it's frequently found on deer) is the vector of the disease in the eastern and midwestern areas of our country. In the western portion of the United States, the disease may be carried by the Western black-legged tick. These black-legged ticks belong to the Ixodes species and they can be found living in shrubs, wood and brush piles as well as grassy and wooded areas. They can be perfectly at home in your yard or the “back forty” if conditions are right.

These blood-sucking parasites have a 2-year, 3-stage life cycle and must feed one time during each cycle. The larval stage is the first stage of their life. They hatch in the spring and summer and generally are not infective at this time, as even though the adult tick might be infected, the spirochete is rarely passed on to the new-borne larvae. They can become infected, however, by feeding on small mammalian hosts which harbor the spirochete. The principal infected host is the white-footed mouse which harbors the spirochete, the cause of Lyme disease.

The nymphal, or 2nd stage of the tick, emerges the following spring and probably is the greatest “spreader” of Lyme disease as it is small and difficult to see. It can feed very fast or stay attached to the host for a week, being hidden in skin folds or hair. The infected tick will only transmit the spirochete after it has engorged. At this time B. burgdorferi is transmitted to the host by the blood or lymphatic systems. In the prevention of Lyme disease this factor becomes very important as the ticks should be sought out and removed before they have a chance to fully feed on the host animal.

It is very interesting to note that in those areas where Lyme disease is prevalent, 20% of nymphal stages and 40% of adult stages of the Black-legged deer ticks are infected with the spirochete which causes Lyme disease. In contrast, it has been found that in the western United States where the host animals for the spirochete are much less in number, only 1 to 3% of these ticks, including their lymphal stages, are infected.

Contrary to what many people believe, deer are not a reservoir for the spirochete. They are only a host for the adult “deer tick.” The increasing incidence of the disease in animals and humans may be due to better diagnostic procedures, increased numbers of Ixodes ticks and expansion of human and horse populations into rural woodland areas. An increased deer population is certainly a factor for the propagation of the adult tick.

The clinical signs of Lyme disease in horses and dogs are varied and sometimes obscure. The most common symptoms in both species are chronic weight loss, sporadic lameness and swollen joints, muscle tenderness and a mild rise in body temperature. Some horses will develop symptoms of a low-grade founder or laminitis. Dogs as well as horses may exhibit signs of a central nervous disorder. In both species, the eyes may become involved with inflammation of the anterior chambers.

In the human family the formation of a bull's-eye or annular rash at the site of a tick bite is almost diagnostic of Lyme disease. This skin rash may come on slow and take a month to become apparent. The disease will progress to involve other body systems including the joints, muscles, nervous and cardiac systems.

The diagnosis of Lyme disease is often difficult. Two blood tests are available for the diagnosis of the disease but their reliability is often in question. Diagnosis of Lyme disease in the horse often depends upon the history, symptoms and, above all, the response to antibiotic therapy. If one suspects the disease in a dog or horse, it should be treated with the appropriate antibiotics and if a favorable response occurs in two to five days, a presumptive diagnosis of Lyme disease can be made. Any one of three drugs is currently being used to treat Lyme disease in the horse. They are tetracycline, doxycycline and cefliofur which can be given orally, intramuscularly or intravenously.

There are three vaccines currently available which can be used in dogs to prevent Lyme disease. There is no licensed vaccine available for use in horses and cats to prevent this disease. A vaccine was approved in 1998 to be used to prevent Lyme disease in humans but it was pulled from the market in 2002 because of arthritic and neurological side effects which developed in patients after its use.

Flea and tick collars, as well as “spot on” drugs, which kill and repel ticks on dogs and cats are readily available for these animals. Their use, especially the “spot on” drugs, will greatly reduce or eliminate the tick infestation on them.

There are several methods which can be employed to repel or kill ticks which may be found on horses. One method I have used is to worm them every 30 days during the tick season with any product made as an equine wormer which contains ivermectin. Another method used to repel and kill the ticks is to spray them with a horse spray which contains pyrethrum. Be sure you spray under the mane and foretop and under the front and rear legs as well as the tail head.

Another preventative measure for the horse is to purchase cattle fly tags which contain pyrethrum or permethrin; braid them into the mane of the horse, one tag for each 1,000 lbs. of weight. Be sure to place them upon the neck so the collar does not affect the tag. I have used this method many times and it works to kill and repel the ticks.

As for the human, “the only effective way to prevent Lyme disease is to avoid being bitten.” A number of repellents are available on the market for use on animals as well as humans. The most effective are those which contain DEET which was developed by the U.S. Army in 1946. A 20% “DEET” product will provide protection for four hours, while a 48 to 98% DEET product may last 12 hours. Usually a 5 to 35% concentrate is sufficient for most peoples' needs.

Picaridin is another excellent repellent. It became available in the U.S. in 2005 and is a synthetic like DEET. It will repel up to eight hours.

For those who would like to use a natural product, Oil of Lemon Eucalyptus really works. A 40% concentration stops ticks and mosquitoes for several hours.

Now, how would you like to just wear some clothes that would repel mosquitoes, ticks, ants, flies, chiggers, midges and no-see-ums? It has been six years since Richard Lane, president of a textile treatments company, Buzz Off™ in Greensboro, N.C., perfected a process which binds permethrin to different fabrics.

Permethrin is man-made and resembles pyrethrum which is found in the chrysanthemum plant. Since 1977, this drug has been used to kill and control insects. In clothing, the chemical is bound tightly to the fabric and will not be absorbed by the skin. West Point cadets, in their training programs, were exposed to Lyme disease-bearing ticks and, as a result, a very high percentage of them suffered from the disease. In 2002, the cadets wore treated uniforms and Lyme disease cases dropped to zero. Today their uniforms are still treated with Buzz Off™.

Buzz Off™ clothing has been certified by the EPA to give insect protection through at least 70 washes. Treated clothing is marketed by Orvis, L.L. Bean, Rocky Outdoor Gear, Stearns, Ex Officio and others. Buzz Off™ has donated thousands of treated garments to foreign countries to protect people from insect-borne diseases. The cost to treat clothing adds about five to 20 dollars to the price of the garments.

The wood tick family has been responsible for spreading a number of other diseases in animals and man. Texas cattle fever, which cost the cattle industry untold millions of dollars, was spread by a tick. Ticks may also transmit malaria-like babesiosis, and the bacterial infection bartonella, human graneclogitive anaplasmoses as well as tularemia and Rocky Mountain spotted fever.

What is the proper procedure in removing a tick which has been found imbedded on an animal or yourself?

There are many folk remedies which are employed to get the tick to release its hold. Rubbing alcohol, nail polish, nail polish remover, turpentine and the glowing head of a match have all been used. Experts on the subject advise not to use these methods. Instead, gently grasp the tick’s head which is embedded in the skin with a small tweezers and pull it straight out. Twisting the tick or putting a substance on it may cause it to inject its poison into you or your patient. Once the tick has been removed, apply some antiseptic agent to the area. Sometimes it may be prudent to place the tick in a small container and submit it to your doctor or a lab for testing.

My father was born in 1898 and as a young boy developed a great appreciation for the out-of-doors. He loved to hunt, fish and just be out in the timber in his spare time. He passed this on to my brother and me. All the wild game that was shot and the fish we caught were prepared and eaten as often this was all the meat we had to eat during the Depression years.

In late April or early May, depending on the weather, we often went to the timber to gather morel mushrooms. In 1963, about two weeks after such a trip to the woods, Dad became quite ill. He developed a rash and a fever. Eventually he ended up in the hospital suffering from severe pneumonia. It was then that his heart was affected as a result of the pneumonia and infection.

Dad returned from the hospital but was never able to work again. It was his damaged heart that failed him in the autumn of 1965, and he passed away at the age of 67, hardly old by today’s standards.

The cause; Rocky Mountain Spotted Fever which was conveyed to him by the bite of an infected Brown Dog tick, probably on his last mushroom hunt.

Be aware of that killer who may be lurking in your yard or “back forty.” Protect your stock and yourself from the tick. It may be the best thing you have ever done.

Here is a list of preventative measures you can take when operating in a tick infested environment:

  • Wear long pants and have them tucked into your socks or boots. Wear long-sleeved shirts. • Do not walk barefoot in grass.
  • Use a repellent such as DEET on your skin. Use permethrin spray on your clothing.
  • To kill ticks on clothing, toss the clothing into a dryer on high heat for 15 minutes. This will kill ticks on the clothing. Ticks can live under water for days, so washing the clothes will not kill them.
  • Check your animals and pets daily so ticks will not jump to you. Most important is to examine horses and dogs.
  • Once a day, do a tick check on your body, especially the groin, navel, armpits, behind your ears and knees. Always check under your shirt collar. Ticks will collect on your shirt in this area.
  • Remove tall grass, leaves, underbrush and old wood piles in your backyard. These materials can be a home for the tick family.
  • Try and wear light-colored clothing as you can spot ticks more easily.
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