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Lyme disease is a multi-system disease that develops from infection with Borrelia burgdorferi. The small, spiral shaped bacterium (spirochete) is transmitted by infected deer ticks (Ixodes scapularis) and black legged ticks (Ixodes pacificus). Ixode ticks are found predominantly on deer, but can also be carried by field mice, rabbits, sheep, and cattle. The disease is transmitted when an infected ixode tick bites a human, exposing him to the Borrelia bacteria. From 1992 to 1998, 92 percent of Lyme disease cases were reported from eight states in the Northeast and Mid Atlantic, as well as Wisconsin and Minnesota.(1) Lyme disease is named after the town in which it was first identified, Lyme, Connecticut. In the early 1970's, a cluster of unexplained arthritis cases appeared among young children in the area. After researching the cases, clinicians were able to determine the source of the illnesses and identify the bacterium responsible.(2)
Lyme disease has proven itself a challenging disease on a number of fronts. The difficulty begins with identification of the disease. Ixode ticks are extremely small, about the size of a pinhead, making them difficult to see. This is especially challenging on areas of the body with hair. Furthermore, tick bites are essentially painless and many people are bitten unknowingly. Initial infections are often asymptomatic, although in about half the cases, a characteristic rash (erythema migrans) appears at the site of the bite. The rash, known as a "bull's eye", is the only hallmark sign of Lyme disease. Blood tests may not be reliable, since it takes as many as four weeks after infection before antibodies can be detected. After several weeks, the most sensitive test, the enzyme-linked immunoassay (ELISA), can be used to confirm a clinical diagnosis, followed up with a Western blot. A new genetic engineering technique, polymerase chain reaction (PCR), is under development, which can detect genetic material from the Lyme bacterium in human fluid and tissue.(3) Furthermore, the disseminated disease resembles many other illnesses, and is often misdiagnosed as chronic fatigue, fibromyalgia, depression, or multiple sclerosis.
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