Human parvovirus (B19) and erythema infectiosum.

An outbreak of erythema infectiosum ("fifth disease") was studied in Fukuoka, Japan, in 1980-1981. Human parvovirus (HPV) antigen was not detected in any patients, but anti-HPV, measured by countercurrent immunoelectrophoresis, was found in 33 of 34 affected children and in 21 (15%) of 141 children of the same ages without the disease. Immunoglobulin M class anti-HPV was present in all 25 children with erythema infectiosum tested. In a survey of hospital patients, the prevalence of anti-HPV detected by CIE was 12% in the cohort 5 to 9 years of age, 19% in the cohort 10 to 14 years, and 32 to 55% in the cohorts greater than or equal to 30 years. The antibody reactions in the cases of erythema infectiosum, which were already well established at the onset of disease, indicate that HPV was the cause of the outbreak.