Thirteen British cases of erythema chronicum migrans, a spirochaetal disease.

Thirteen British cases of erythema chronicum migrans are reported. An antibody to the Lyme disease spirochaete was found in three of five recent cases, but Lyme disease was not seen. The distribution and life cycle of the tick Ixodes ricinus is described and related to the occurrence of erythema chronicum migrans in Great Britain.