Lyme disease is an infectious disease caused by Borrelia burgdorferi, a bacterium classified as a spirochete. Borrelia burgdorferi thrives inside of certain ticks (e.g. deer ticks) and can be spread to humans by the bite of an infected tick. There are three stages of Lyme disease: early localized stage, early disseminated stage, and late stage. Lyme disease is named after the town where it was first discovered in 1975 - Lyme, Connecticut.
As described, Lyme disease is caused by the transmission of Borrelia burgdorferi which live inside of infected ticks. The bacteria, which lives in the tick gut, travels to the mouthpart of the tick and is injected into the skin. People who are most at risk of developing Lyme disease usually spend a lot of leisure time outdoors in tick-infested wooded areas (e.g. campgrounds) or live in densely wooded areas. In the United States, in the Northeast and Upper Midwest areas, there is a peak of infection in late spring and early summer. A smaller peak follows in the fall season.
- Early localized stage of Lyme disease is characterized by erythema migrans, a skin rash which appears from three days to several weeks after the bite. The small rash grows in diameter, becoming anywhere from two to 10 inches.
- With early disseminated stage, the infection spreads to the rest of the body in the weeks following the tick bite and may cause multiple skin rashes, fever, joint pain, muscle pain, headaches, possible heart and nervous system issues. Others may appear symptom-free.
- Late stage infection (months or years after onset) can lead to chronic arthritis or nervous system involvement.
Laboratory tests are used to confirm Lyme disease when patients present symptoms which are consistent with Lyme disease. The Centers for Disease Control and Prevention recommends an ELISA blood test to detect certain antibodies produced as a response to the infection. Another test, known as the Western blot, is used to confirm borderline or positive results from the first test. False negative test results are possible for patients in the early weeks after infection.
Early stage Lyme disease is usually treated with a two to three week course of oral antibiotics. Intravenous (I.V.) antibiotics may be indicated if early infection shows signs of heart or nervous system involvement. Antibiotic treatment is still considered successful for most patients even if infection is unrecognized at first or detected in its later stage. There are some patients who have problems which linger on, even following treatment, such as persistent joint pain and arthritis.
According to the Centers for Disease Control and Prevention, there were 23,305 cases of Lyme disease reported in 2005 yielding a national average of 7.9 cases for every 100,000 persons in the United States. In the ten states where Lyme disease is most common, the average was 31.6 cases for every 100,000 persons. States with the highest prevalence of Lyme disease include, in order: Delaware, Connecticut, New Jersey, Massachusetts, Pennsylvania, New York, Wisconsin, Maryland, New Hampshire, and Maine.
- If Lyme disease is diagnosed and treated early, it is usually the case that symptoms quickly disappear.
- Fatigue and poor sleep can be problematic for patients who remain untreated or undiagnosed.
- Prevention is the best course for avoiding Lyme infection: avoid brush and tall grass, use tick repellant, wear light-colored clothing, tuck long pants into socks, and check for ticks regularly.
- If a tick is discovered within 24-36 hours of attachment, removing it with tweezers will usually prevent disease transmission.
- There is currently no vaccination to prevent Lyme disease.
Sources:
1. "Learn About Lyme Disease". CDC. April 27, 2007. <http://www.cdc.gov/ncidod/dvbid/lyme/index.htm>
2. "Lyme Disease". American College of Rheumatology. May 2005. <http://www.rheumatology.org/public/factsheets/lyme_new.asp?aud=pat>
