We report a case of tick bite caused by Amblyomma testudinarium with a clinical feature of erythema migrans. The patient, a 60-year-old female, went hiking in the Rokko mountains in Hyogo prefecture on June 30. An erythematous macule with mild itching and a biting tick was found on the right side of her abdomen on July 2. On the first visit (July 4), an annular erythema of 10 cm in size was recognized on the abdomen. She had no systemic symptoms and laboratory data were within normal limits. The tick was identified as a nymph of Amblyomma testudinarium. The skin rash was successfully treated with topical corticosteroids and had almost disappeared 2 weeks later without antibiotics. Serum antibody titers against Borrelia afzelii , B. burgdorferi, and B. garinii on the first visit and 1 month later were negative. These results indicate that the skin rash in this case, erythema migrans, was not associated with Lyme disease but an allergic reaction to salivary gland substances of the tick. Similarities between southern tick-associated rash illness and our case (tick-associated rash illness) are also discussed in this report.
