There are blood tests to check for antibodies to the bacterium that causes Lyme disease. The tests, however, are not useful if done soon after a tick bite, because it takes 2 to 5 weeks after being bitten by an infected tick for antibodies to develop. Even when an antibody (blood) test is done later, the result alone does not reliably predict the presence or absence of Lyme disease. (See "How is Lyme disease diagnosed?" below.) The Food and Drug Administration (FDA), which regulates diagnostic tests for Lyme disease, has cleared for commercial sale and distribution only blood tests for antibodies that may be present in Lyme disease. Tests for Lyme disease that use urine or other body fluids have not been cleared by FDA.

 

How is Lyme disease spread?

Lyme disease is spread by the bites of Ixodes ticks (the deer tick, bear tick, western black-legged tick, or black-legged tick, depending on the region of the country). These ticks are much smaller than the common dog or cattle ticks. They can attach to any part of the body, often to moist or hairy areas such as the groin, armpits, and scalp.

Campers, hikers, outdoor workers, and gardeners are at the greatest risk of exposure to infected ticks. Lyme disease is widely distributed in northern temperate regions of the world. In the United States, the highest incidence occurs in the Northeast, North Central states, and the West Coast (particularly in northern California).

What are the symptoms of Lyme disease?

The symptoms of early Lyme disease include:

• a characteristic skin rash (called erythema migrans),
• muscle and joint aches,
• headache,
• chills and fever,
• fatigue, and
• swollen lymph nodes.

Erythema migrans is a circular red patch that usually appears in 3 to 30 days after being bitten by an infected tick. The patch expands (to an average of 5 to 6 inches in diameter) and persists for 3 to 5 weeks. Sometimes many patches appear and vary in shape depending on their locations. The center of the patch may clear as the rash enlarges, giving a "bull's-eye" appearance. In some persons, the characteristic rash never forms or is not noticed, and not every rash that occurs at the site of a tick bite is due to Lyme disease. In some cases, the rash can be an allergic reaction to the tick saliva.

The symptoms of late Lyme disease may not appear until weeks, months, or even years after a tick bite and include:

• arthritis (usually as pain and swelling in large joints, especially the knee);
• nervous system abnormalities such as numbness, pain, facial paralysis similar to Bell's palsy, and meningitis (fever, stiff neck, and severe headache); and
• irregularities of the heart rhythm.

How is Lyme disease diagnosed?

Lyme disease can be difficult to diagnose, because its symptoms mimic those of other diseases. For example, the fever, fatigue, and muscle aches can be mistaken for influenza or infectious mononucleosis. Joint pain can be mistaken for rheumatoid arthritis and neurologic signs for multiple sclerosis. Conversely, other types of arthritis or neurologic diseases can be misdiagnosed as Lyme disease.

To make a diagnosis of Lyme disease, the following should be considered:

• a history of possible tick bite, especially in areas of the country known to have Lyme disease;
• symptoms; and
• results of blood tests done at least 5 weeks after the tick bite to determine if antibodies to the bacterium Borrelia burgdorferi are present in the patient.

Can Lyme disease be treated?

If there are definite symptoms of Lyme disease, the doctor may prescribe antibiotics which are usually given by mouth. Antibiotics should not be given only because a person was bitten by a tick. Patients who are diagnosed and treated with antibiotics in the early stages of Lyme disease usually recover quickly and completely. Most patients treated in the later stages of Lyme disease also respond well to antibiotics. A few patients may have relapses and need additional antibiotic treatment. Permanent damage to the joints or the nervous system can develop in patients with chronic late Lyme disease. Usually these are patients not diagnosed in the early stages or their initial treatments were unsuccessful.

What precautions can be taken to reduce the chance of getting Lyme disease?

To decrease the chance of being bitten by a tick:

• avoid wooded, brushy, and grassy areas, especially in May, June, and July. (Contact the local health department or park/extension service for information on local distribution of ticks.)
• wear light-colored clothing, so that ticks can be seen more easily.
• wear long pants and long-sleeved shirts.
• wear shoes that cover the entire foot.
• tuck pant legs into socks or shoes and shirt into pants.
• wear a hat for extra protection.
• spray insect repellent containing DEET on clothes and exposed skin other than the face, or treat clothes with permethrin that kills ticks on contact.
• walk in the center of trails to avoid brush and grass.
• after being outdoors, remove clothing and wash and dry it at high temperatures.
• do a careful body check for ticks. To remove a tick, use tweezers and grasp the tick close to the skin. Pull straight back and avoid crushing the tick's body. Save the tick for possible identification by a doctor or the local health department.

Is there a vaccine for Lyme disease?

FDA recently licensed the first vaccine to aid in the prevention of Lyme disease. The new vaccine (trade-name Lymerix) is approved for use in persons 15 to 70 years of age who live or work in grassy or wooded areas where infected ticks are present. It is not currently available for persons under the age of 15 years.

Three doses of the vaccine, given over a period of one year, are needed. Although Lymerix may provide protection for a majority of people, it does not prevent all cases of Lyme disease. Studies by the manufacturer showed that after two doses of the vaccine in the first year, the protection rate against definite Lyme disease was 50 percent. In the second year after three doses, it was 78 percent. Since the vaccine is not 100 percent effective, continued preventive measures are still necessary for immunized individuals.

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