Multisystem illness caused by the spirochete Borrelia burgdorferi, carried by the deer tick
- Can affect people of all ages, but 1/3 to 1/2 of all cases occur in children and adolescents
- Male/female ratio: 1:1 to 2:1
- Onset most often in summer months
- Although Lyme disease can be found anywhere, the majority of the cases in the United States are found in Southern New England and the mid-Atlantic states. It is also seen frequently in California, Minnesota, and Wisconsin.
- The most common tick-borne disease in the United States, with incidence in 2015 of 8.9/100,000.
- However, incidence varies significantly in different parts of the country and 95% of all cases reported were found in 14 states: Connecticut, Delaware, Maine, Maryland, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, and Virginia.
- Outside of those states, Lyme disease remains rare.
Chronic Lyme arthritis seems to be associated with increased incidence of HLA-DR4 and less so with HLA-DR2.
- B. burgdorferi is injected into skin with saliva during bite of Ixodes tick.
- Spirochetes first migrate within skin, forming the typical rash, erythema migrans.
- Spirochetes then spread hematogenously to other organs, including heart, joints, and nervous system.
The tick-borne spirochete B. burgdorferi
Commonly Associated Conditions
The same ticks that transmit Lyme disease can also transmit Ehrlichia and Babesia, so infections with those spirochetes can occur simultaneously.
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