Lyme Disease Introduction
What is Lyme disease?
Lyme disease is an infection caused by a spirochete (say “SPY-ROH-KEET”) that humans can get from the bite of an infected deer tick. The spirochete's scientific name is Borrelia burgdorferi. Lyme disease is called “The Great Imitator” because its symptoms mimic many other diseases. It can affect any organ of the body, including the brain and nervous system, muscles and joints, and the heart.
How do people get Lyme disease?
People usually get Lyme disease from ticks infected with Lyme spirochetes. Most human cases are caused by the nymphal, or immature, form of the tick. 
Nymphs are about the size of a poppy seed. Because their bite is painless, many people do not realize they have been bitten.
If you think you might have Lyme Disease, click here to find out what to do.
Ticks may remain attached for several days while they feed. The longer they remain attached, the greater the risk that they will pass the Lyme bacteria into your bloodstream, where they will start spreading throughout your body.
If pregnant women are infected, they sometimes pass Lyme disease to their unborn children. Some doctors believe other types of human-to-human transmission are possible but little is known for certain.
Where is Lyme disease found?
Lyme disease has been found on every continent except Antarctica. It is found all across the United States, with a particularly high incidence in the east, midwest, and west coast. It seems to be spreading.
Not all ticks are infected. Within endemic areas, there is considerable variation locally, depending on type of habitat, presence of wildlife, and other factors. In the south, a Lyme-like disease is called STARI (Southern Rash-Associated Tick Illness).
In addition to the variation that occurs in nature, there is also variation in how aggressively the states have tested ticks for infection. Thus, many times the reported incidence of infected ticks reflects the fact that the state has done little or no testing of ticks in the area. Click here to view maps that show a dramatic increase in the number of states reporting Lyme to the Centers for Disease Control for the years 1985, 1987, and 1992. Some of this increase may be because of disease spread, but it is also likely that it reflects growing public awareness of the disease.
