Lyme disease was first reported in 1975 after researchers investigated why unusually large numbers of children were being diagnosed with juvenile rheumatoid arthritis in Lyme, Connecticut, and two neighboring towns. Scientists soon discovered the disease was caused by a corkscrew-shaped bacterium called Borrelia burgdorferi passed to humans through the bite of a tick. The bacterium is carried by the deer tick in the eastern and central United States and by the Western black-legged tick on the Pacific coast.
In 1999, 16,273 cases were reported to the Centers for Disease Control and Prevention. In the United States more than 90 percent of all reported cases occur in the Northeast, mid-Atlantic, and the upper Midwest. Few cases have been reported in northern California and remaining states.
The first sign of Lyme disease is often a circular or bullseye-like rash appearing at the site of a tick bite within a few weeks of the bite. Sometimes the rash is the first sign a person has been bitten. As the rash progresses it can appear on other sites of the body. The disease is easily cured at this stage with antibiotics, so careful attention to the symptoms is critical for proper care. If left untreated, many people develop pain and swelling in the joints, which may progress to chronic arthritis. In some cases, neurological symptoms also appear.
To reduce the risk of infection, a Lyme disease vaccine (LYMErix(r)) is available for use by people who live in endemic areas and are at high risk for developing the disease.
SOURCE: National Institute of Allergy and Infectious Diseases
Last updated August 5, 2003