Lyme disease is an infection caused by bacteria called Borrelia burgdorferi. These bacteria are transmitted through the bites of ticks, primarily the deer tick. Not everyone who develops symptoms of Lyme disease remembers getting bitten by a tick because the deer tick is very small and its bite can go unnoticed.
Lyme disease is most common in the northeastern and midwestern United States. More than 90% of cases have been reported in nine states: Connecticut, Maryland, Massachusetts, Minnesota, New Jersey, New York, Pennsylvania, Rhode Island and Wisconsin. Even within states, there are regions of high risk and others with very low rates of disease. This variation relates to where ticks that carry the bacteria live, breed and come into contact with humans.
Lyme disease infection recently has caused a great deal of public concern and confusion. Lyme disease is usually not responsible for causing chronic fatigue syndrome or other poorly defined problems. Lyme disease is a distinct illness that causes its own very specific signs and symptoms and can be readily diagnosed. Unexplained medical conditions should not be attributed to Lyme disease simply because no other diagnosis seems likely.
The first symptom is a rash called erythema migrans (EM), which is usually a flat, reddish rash that spreads from the site of the tick bite. The rash usually is larger than 2 inches wide and can grow larger. It often develops a central clear area known as a bull's eye. The rash usually doesn't itch or hurt. Other symptoms at this stage can include fever, muscle and joint aches, fatigue, headache and a severe stiff neck. In some cases, there are two or more of these well-defined rashes.
Over several days to weeks after the tick bite, Lyme disease can cause neurological problems, including meningitis, which is an infection of the lining of the brain and spinal cord; and Bell's palsy, a weakness in facial muscles caused by nerve injury. Lyme disease also can cause carditis, an inflammation of the heart muscle that can cause irregular heart rhythms with fainting or dizziness. Months to years after Lyme disease affects the heart, changes can be seen on an electrocardiogram (EKG) even when there are no symptoms. Lyme disease also can cause either a chronic arthritis that commonly affects one knee or episodes of swelling in several joints, called migratory arthritis.
In later stages of Lyme disease, patients can experience problems with memory and concentration.
Your doctor will ask about your symptoms and perform a complete physical and neurological examination. If you have had a recent tick bite and have saved the tick, your doctor may want to inspect the insect and send it to a laboratory to identify the species. Some laboratories can analyze the tick to see if it's carrying Lyme bacteria.
Your doctor will diagnose Lyme disease based on your symptoms and the examination. Blood tests are often negative in the first four to six weeks of Lyme disease. The basic Lyme test is called an ELISA (enzyme-linked immunosorbent assay). However, this test often gives a false-positive result, that is, a positive result in someone who doesn't have the illness. Therefore, every positive or uncertain Lyme ELISA result needs to be confirmed with a test called a Western blot, which looks for more specific evidence of Lyme disease infection.
A positive Lyme blood test, even including a Western blot, doesn't mean that the disease is active and needs to be treated. This is because blood tests can remain positive for years, even after Lyme disease has been treated or has become inactive. To help diagnose Lyme disease and to check for other causes of symptoms, a sample of fluid may be withdrawn from an affected joint using a sterile needle. Cerebrospinal fluid also may be taken from around the spinal cord through a spinal tap (lumbar puncture), to test for Lyme disease antibodies and inflammation and check for other diseases.
People often recover within two to six weeks without antibiotics. Even Lyme arthritis often improves on its own as the body's immune system attacked the infection, although it's common for it to return. Antibiotic therapy is highly effective at curing the illness. Significant improvement occurs within two to six weeks after beginning therapy.
If you are in a region where Lyme disease is more common, you can:
- Avoid woods, high brush, and grasses where ticks hide
- Wear long pants and long sleeves; white clothing makes is easier to spot ticks
- Examine your skin for ticks soon after returning from wooded areas or areas with high grass or brush
- Apply tick repellents (especially those that contain DEET) to the skin and clothing
Antibiotics are not prescribed for every tick bite, because the risk of getting Lyme disease is quite low, ranging from less than 0.1% in most areas to 5% in some areas of the Northeast and Midwest. For people that live in areas where Lyme disease rates are high, one dose of doxycycline can usually prevent disease if taken within three days of a tick bite. So for those at highest risk, early treatment may be appropriate. A Lyme disease vaccine is not currently available for humans.
For the early Lyme EM rash, doctors usually prescribe two to three weeks of antibiotics. Doxycycline is the preferred treatment. Alternative antibiotics include amoxicillin and cefuroxime (Ceftin). In people who have developed Bell's palsy, arthritis or carditis, this antibiotic treatment often is extended to four weeks. Some people with heart or neurological problems will be treated with antibiotics such as ceftriaxone (Rocephin) given intravenously (into a vein) for two to four weeks. Intravenous treatment also may be recommended if a person with Lyme arthritis does not respond to oral antibiotics. Doxycycline should be avoided in children less than 8 years old and for women who are pregnant or nursing. Erythromycin, azithromycin or clarithromycin may be less effective but are often prescribed for people with Lyme disease who can't tolerate the other options mentioned above.
Call your doctor if you develop a rash or flulike illness after you have been bitten by a tick or you could have been exposed to ticks. You should also call your doctor if you have facial paralysis, arthritis, or persistent dizziness or heart palpitations.
If you are taking oral antibiotics for Lyme disease and your symptoms do not improve within two to three weeks, call your doctor.
People with the Lyme disease rash rarely have problems after they are treated with antibiotics. In some cases, people become extremely tired after being treated for Lyme disease, but this problem doesn't tend to improve with additional antibiotics. The medical reason for this fatigue is uncertain. Many, and perhaps most, people with persistent symptoms have no clear evidence of active infection. Intensive antibiotic treatment (for example, intravenous treatment for prolonged periods) usually doesn't help.
About 10% of people with Lyme arthritis appear to have chronic (long-lasting) joint swelling despite taking antibiotics. Recent evidence suggests this is caused by an autoimmune effect, in which Lyme infection triggers the immune system to attack the body's own cells. This problem seems to follow Lyme disease primarily in people of certain genetic types. These people may respond to medications that suppress the immune system (similar to those used in rheumatoid arthritis) rather than to continued antibiotics.
Infectious Diseases Society of America
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Centers for Disease Control and Prevention (CDC)
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