An epidemic of infantile papular acrodermatitis (Gianotti's disease) in Japan associated with hepatitis-B surface antigen subtype ayw.

An epidemic of infantile papular acrodermatitis (I.P.A.) (Gianotti's disease) occurred in Matsuyama City, in south-east Japan in 1974-75. Patients ages ranged from less than one year to eight years. Hepatitis-B surface antigen (HBsAg) was detected by an immune adherence haemagglutination method in the serum samples of 48 of the 54 patients tested. HBsAg subtypes were determined by a haemagglutination-inhibition method. ayw antigens were identified in 42 patients and adr antigens in 3; it was not possible to determine subtypes in the remaining 3 patients because antigen titres were too low. Since subtype ayw and I.P.A. are extremely rare in Japan, the association of the disease with HBsAg subtype ayw is regarded as being most significant.