Erythema migrans

Erythema migrans or erythema chronicum migrans is an expanding rash often seen in the early stage of Lyme disease, and can also (but less commonly) be caused by southern tick-associated rash illness (STARI). It can appear anywhere from one day to one month after a tick bite. This rash does not represent an allergic reaction to the bite, but rather an actual skin infection. The rash's name comes from Neo-Latin for "migrating redness."