To describe the natural history of a condition or disease. To describe the natural history of a condition or disease. To determine effectiveness or cost effectiveness of treatments/services and/or health care products. To measure or monitor safety and harm. To measure quality of care.
According to the NMSS, attacks or flare-ups of symptoms only qualify as exacerbations if: 1  they occur at least 30 days from an earlier flare-up. 2  symptoms last for 24 hours or longer.
Erythema migrans. Erythema migrans, a red expanding patch of skin, is the most typical sign of Lyme disease and is present in 70â80% of cases. It usually appears 7â14 days (range 3â33 days) after the infected tick bite. It starts at the site of the tick bite as a red papule or macule that gradually expands.