[Serum antibodies against Ixodes ricinus Spirochaeta in acrodermatitis chronica atrophicans (Herxheimer)].

Using indirect immunofluorescence, IgG antibodies against the recently detected Ixodes-ricinus-spirochaeta, which causes erythema chronicum migrans could be demonstrated in all 21 persons with acrodermatitis chronica atrophicans. Titers were from 1 : 64 to 1 : 1024, specific IgM antibodies were demonstrable in only 5 patients in a titer of 1 : 64. Even after treatment with penicillin high IgG antibody titers of up to 1 : 1024 were found. Fourfold decreases could be found only once for each IgG and IgM antibodies.l Serology indicates that acrodermatitis chronica atrophicans as well as erythema chronicum migrans is caused by the Ixodes-ricinus-spirocheta.