General Facts About Lyme Disease and its Transmission

Lyme disease is named after the town of Old Lyme, Connecticut, where it was discovered in 1975. The disease is a bacterial infection transmitted by the bites of certain, very small, infected ticks. The two most important ticks are the deer tick in the Northeast and in the north-central states and the western black-legged tick in the West. These ticks are much smaller than the common dog or cattle tick. The onset of the disease most commonly occurs during the summer months when ticks are most active; however, later symptoms of untreated Lyme disease can occur at any time of the year. Although the deer ticks which carry the disease are slowly expanding into new areas, there are three areas where risk of getting the disease is much greater than elsewhere.

• the east-coastal states of Massachusetts, Connecticut, Rhode Island, New York, New Jersey, Pennsylvania, Maryland, and Delaware;

• the north-central states of Wisconsin, Minnesota, and Michigan, and, finally,

• northern California

Lyme disease and the ticks that carry it are rare or nonexistent in the Rocky Mountain states, Hawaii, and Alaska.

Symptoms of Acute Lyme Disease

The first sign of Lyme disease in most patients is the large red skin rash called erythema migrans (EM). The rash usually appears in the summer months and is accompanied by "flu-like" fever, headache, tiredness, and vague aches and pains in muscles and joints. Some persons will have swollen lymph glands. Most persons treated with the appropriate antibiotics at this stage will have a quick recovery and will be completely cured.

The characteristic rash of Lyme disease, EM, expands outward from the site of the tick bite beginning 3 to 30 or more days after the bite. A rash which occurs in the 48 hours immediately after a bite is due to an allergic reaction and is not Lyme disease. The Lyme disease rash is flat, circular, and usually reaches a size of at least 2 inches in diameter. As the rash expands, the central portion partially clears, while the outer margins redden. This gives the rash a bull's-eye appearance. The single rash can become quite large and may be accompanied by one or more scattered rashes on other areas of the skin. These rashes clear quickly with antibiotic therapy.

Patients who do not receive treatment for early Lyme disease can develop further problems involving the heart, joints, or nervous system as the disease progresses. The most frequent heart problem is a relatively mild disturbance of heart rhythm. With treatment, this rhythm disturbance almost always clears very quickly with no apparent long-term damage. In very rare cases, there is serious heart muscle damage which may lead to heart failure.

Infection of the nervous system can progress to meningitis, paralysis of facial nerves, inflammation of the brain, or painful disorders and weakness in the limbs caused by nerve inflammation. When these conditions occur relatively soon after the initial infection, they generally respond well to intravenous antibiotics. Patients with untreated arthritis may develop more severe involvement of one or more joints, most often, large joints such as the knee, the shoulder, or the elbow. Fluid often collects in the affected joints and causes swelling. These early stages of arthritis respond well to intravenous antibiotics in most instances.

Lyme disease can be diagnosed in the laboratory by isolating the bacteria or by detecting antibodies against the bacteria in blood, but most often requires biopsy of the EM skin lesion and the use of special bacterial media. Detecting antibodies in blood is the most common test performed. Antibodies are usually present in the blood in the chronic stages of Lyme disease, but are frequently not found in the early stages of illness. Some positive antibody tests for Lyme disease are false-positives. Research to remedy this problem is under way.

Symptoms of Chronic Lyme Disease

Chronic Lyme disease may include abnormalities in the skin, the joints, and the nervous system. Chronic abnormalities in the skin are rare in the United States.

Chronic arthritis is the most widely recognized result of untreated Lyme disease. It most often affects one or a few large joints and usually the knee. It is considered chronic because it recurs in episodes lasting for as long as 6 months. Unlike most other forms of arthritis, chronic Lyme arthritis does not usually attack the same joint on both sides of the body at once, and does not affect many joints at once. When Lyme disease does affect a joint, it usually causes swelling with redness and accumulation of fluid in the joint. Lyme arthritis usually responds to antibiotic treatment; however, if severe joint damage has occurred, complete recovery may not occur or may take a long period of time.

Chronic Lyme disease infection of the nervous system most often produces pain in arms or legs along with weakness and/or numbness in the affected limbs. These problems are caused by Lyme disease infection of the spinal cord. With infection of the brain, a number of other problems can occur. These include headaches, severe fatigue, impaired vision, double vision, hearing impairment, facial paralysis, and difficulties with memory and thinking.

It is important for you to know that all these symptoms including those of the skin, joints and nervous system, can be caused by many things other than Lyme disease. A number of special tests are available to determine the cause of these symptoms. If you are concerned about this, you should consult your physician for advice and treatment.

Lyme disease can be diagnosed in the laboratory by isolating the bacteria or by detecting antibodies against the bacteria in blood, but most often requires biopsy of the EM skin lesion and the use of special bacterial media. Detecting antibodies in blood is the most common test performed. Antibodies are usually present in the chronic stages of Lyme disease, but are frequently not found in the early stages of illness. Some positive antibody tests for Lyme disease are false-positives. Research to remedy this problem is under way.

If you and your physician are concerned about the accuracy of your Lyme disease test results, your state health department laboratory can act as a reference laboratory to assist you.

Treatment of Lyme Disease

If your symptoms are diagnosed as due to Lyme disease, your physician will prescribe an antibiotic for treatment. The antibiotic he chooses for your treatment will usually be in one of four general groups; a penicillin, a cephalosporin, a tetracycline, or an erythromycin. The antibiotic chosen will depend on a number of factors such as allergic history, age, pregnancy, and stage of disease. Antibiotics may be given orally, intravenously, or possibly intramuscularly as determined by your physician.

The response of patients to treatment for chronic Lyme disease is variable. If a person has had untreated Lyme disease for many years, damage to the nervous system or joints may require a prolonged period for repair after the infection has been eradicated. In some instances, treatment seems to have little or no beneficial effect.

Prevention of Lyme Disease

The only certain way to prevent Lyme disease is to avoid all situations of exposure to infected ticks. For many people, this is not possible or is not acceptable. In these situations, there are a number of steps you can take which will greatly reduce your chances of acquiring Lyme disease.

1. Wear long pants. Tuck pants legs into long socks or seal pants legs with masking tape or rubber bands.

2. Spray a permethrin-containing tick repellent on clothes.

3. Use a repellent containing the compound DEET on your skin areas that are exposed, except for the face area. Follow label directions carefully, and be especially cautious when using DEET on children.

4. Check your entire body carefully for ticks twice a day, including inspection of the neck and scalp. If you are alone, the use of a fine tooth comb will help locate adult ticks in your hair.

5. Remove attached ticks from your skin immediately with tweezers by grasping the tick's mouth parts as close to your skin as possible and applying slow steady traction. Do not attempt to get ticks out of your skin by burning them or coating them with anything such as nail polish remover or petroleum jelly.
6. If you remove a tick before it has been attached for more than 24 hours, you greatly reduce your risk of infection.

7. There is presently no FDA approved vaccine available for protecting humans against Lyme disease; however, two U.S. manufacturers are presently conducting federal trials of experimental vaccines.

8. Antibiotics are not routinely recommended for tick bite in the absence of symptoms of acute Lyme disease.

SOURCE:
Centers for Disease Control