Epidemiology of an outbreak of erythema infectiosum in Tokyo.

Endemic outbreaks of erythema infectiosum were observed in various areas of Japan from 1977 to 1981. Even in a limited district of Tokyo, we recorded 395 cases until June 1981, so this might be the largest epidemic in Japan. Most cases occurred from January to June. The peak incidence was at the age of 7 years and the average age was 8.9 years. The outbreak also occurred among our hospital nurses, but no severe case was observed in hospitalized patients. Furthermore, the symptoms in adults were as mild as in children, suggesting the little participation of immunity in this disease. By epidemiologic survey, erythema infectiosum was distinct from rubella.