What Is Lyme Disease?

Lyme Disease (LD) is an infectious disease syndrome spread primarily by a tick as small as the period at the end of this sentence and no larger than the head of a pin. It is caused by a spiral-shaped bacterium called a spirochete that is transmitted to animals and humans by the bite of the tick. In people, the disease can appear to be as simple as the Flu or as serious as Alzheimer's Disease. If untreated, it can lead to joint damage and heart and neurologic complications. In animals, the disease can mimic flu-like symptoms of chronic arthritis and can lead to joint damage, heart complications and kidney problems. Studies indicate dogs are 50% more susceptible to LD than humans.

Where Is Lyme Disease Found?

First discovered in Connecticut in 1975, Lyme Disease has been reported in 43 states, including Pennsylvania. There has been a sharp increase in the incidence of the disease in all parts of Pennsylvania in the past several years. The tick that spreads LD was once thought to be found only in wooded areas and tall grasslands. It is now found on suburban and urban lawns and on almost any grassy field where you take your dog for its daily run or the park where you like to picnic. It also is found where horses and cows pasture and stable.

How Is It Transmitted?

Several species of ticks transmit the disease. In Pennsylvania and other Northeast and Midwest states, the common carrier and transmitter is the "deer tick" or "bear tick" whose scientific name is Ixodes dammint. This tick lives about two years, becoming inactive during the winter, and feeds only three times, once each in its larval, nymphal and adult stages. During the first stage, the larval ticks feed on a variety of rodents and rabbits, but prefer to feed on the white-footed mouse, common throughout much of the United States. These hosts infest the almost invisible larvae with the infectious organism, Borella burdorferi, and the juvenile tick is ready to feed on and infect animals and humans. After its first meal and molt, it becomes a nymph. Nymphs also feed on the white-footed mouse, but add other rodents, the white-tailed deer, squirrels, birds, cows, dogs and humans as sources of meals, infecting them with the spirochete. The adult tick primarily feeds on larger animals, deer, horses, cows, dogs and humans. The greatest chance of becoming infected by the bite of the tick occurs during May through September, the period of greatest nymphal tick activity. There is a moderate risk in the fall months and low risk during winter. It is important to remember that not all ticks carry Lyme Disease. A tick bite does not necessarily mean that the disease will follow and prompt removal of a tick will lessen chances of disease transmission.

What Are The Symptoms?

Lyme Disease is not easy to detect for there are a variety of symptoms. Clinical Signs may not appear for a long period after initial infection.

In humans, there are typically three stages to the disease. The first symptom is usually a skin rash that occurs at the site of the tick bite within 3 to 32 days. The rash begins as a small red area which gradually enlarges, often with a partial clearing in the center of the lesion so that it resembles a doughnut or bulls eye. However, about 30% of people do not develop a rash. Other skin signs may include hives, redness of the cheeks and under the eyes and/or swelling of the eyelids with reddening of whites of the eyes. These signs may be accompanied by flu-like symptoms such as fever, headache, stiff neck, sore and aching muscles and joints, fatigue, sore throat, and swollen glands. The next stage can affect the central nervous system and heart. Headaches, neck pain, and rapid or irregular heartbeats are commonly found in the second stage. Finally, chronic arthritis and neurologic abnormalities can develop.

The stages in dogs and other animals, however, are not as well defined. This makes it difficult for veterinarians to diagnose the disease. The problem is that animals seldom develop the rash found in people. The common clinical signs are fever (102.5 to 106F), inappetence, acute onset of lameness with no history of trauma, and arthralgia. These can develop within weeks of initial infection. Recurring lameness, lymphadenopathy, glomerulonephritis, or myocarditis can develop weeks to months later. In addition to these signs, cows and horses may have chronic weight loss, abortions, and laminitis-like signs.

How Is It Diagnosed?

Diagnosis is based primarily on recognition of the typical symptoms of LD and by blood testing. It should be noted that early in the disease, the blood test can be negative even though the disease is present. Only with later disease does the test become reliably positive.

What Is The Treatment?

Antibiotics -- tetracycline, penicillin and erythromycin -- have been shown to be effective in treating the disease in both animals and humans in the early stages. If detected early enough, there is almost complete relief of pain and lameness within 24 hours of initial treatment in animals. Chronic cases of the disease respond much slower and require longer periods of treatment.

How Can It Be Prevented?

Knowledge of where these ticks are found, avoidance of such areas, and, if bitten, prompt removal of the tick are the primary preventive measures. Persons living in areas where ticks are prevalent should:

• Avoid walking barelegged in tall grass, scrubby areas or woods. If you do walk in such areas, wear a long-sleeved shirt, long pants and high socks with pants tucked tightly into socks.
• Use a reputable tick repellent on your dog--your veterinarian has them available or can prescribe the most advanced products on the market today -- and use a repellent on yourself when camping or walking through areas likely to have ticks.
• Conduct daily tick checks on your dog, on yourself, and members of your family.

To remove a tick, use small tweezers to firmly grip the tick's mouth parts as close to the skin as possible and pull it straight outward. Apply an antiseptic to the bitten area. After removing, destroy the tick by immersing it in alcohol. Save the tick, marking the date it was found on the body, in the event that symptoms arise and identification of the tick becomes necessary.

If your dog has been in an area where the tick is found, or if you have found a tick on its body and it develops any of the symptoms mentioned above, make an appointment with your veterinarian for an examination, blood test and possible treatment. The blood test may have to be repeated several months later. It would be wise, whether or not you have found a tick on your dog, to have it tested in the spring and fall to assure yourself that your pet does not have Lyme Disease.

It is not as easy to detect ticks on horses and cows, particularly in herds, but horse owners and farmers should be alert to any sudden onset of fever, lameness, abortions, laminitis-like signs or chronic weight loss in their animals and should consult with their veterinarian for evaluation.

If you have been in an area where the tick is found, or if you have found a tick on your body and develop any of the symptoms mentioned above, you should see your physician for evaluation and treatment.