Lyme disease.Erythema chronicum migrans. Expanding “bull’s eye” red rash.
Caused by Borrelia burgdorferi,which is transmitted by the tick Ixodes A (also vector for Babesia). Natural reservoir is the mouse.Mice are important to tick life cycle.
Common in northeastern United States.
Later symptoms—monoarthritis (large joints) and migratory polyarthritis, cardiac (AV nodal block), neurologic (encephalopathy, facial nerve palsy, polyneuropathy).
Treatment: doxycycline, ceftriaxone.