Several publications concerning the methods of real-time PCR for human parvovirus B19 (B19V) have appeared and some case reports mention B19V
DNA loads. However, no large-scale study quantitating levels of B19V
DNA in common or representative B19V manifestations such as
erythema infectiosum and aplastic crisis has been performed. Consequently, using the TaqMan PCR assay, the B19V load in a large sample of subjects with
erythema infectiosum or aplastic crisis was quantitated. Sixty-five subjects in the acute phase of
erythema infectiosum were involved, and in addition 22 serum samples from seven subjects with B19V-associated aplastic crisis complicating chronic
hemolytic anemia were also analyzed. In the acute phase of
erythema infectiosum the median B19V
DNA load in the serum samples from the acute phase of
erythema infectiosum was 7.63 × 10(5) genomes/ml, (range from 4.48 × 10(3) to 8.31 × 10(6) genomes/ml). The serum B19V
DNA load during the acute phase of aplastic crisis complicating chronic
hemolytic anemia was extremely high, that is 10(10) -10(13) genomes/ml, and decreased gradually to around 10(5) genomes/ml over 1-2 months. Although all subjects followed an almost uniform and typical
clinical course of
erythema infectiosum, there was a large individual variation of B19V
DNA loads, that is differences of over 1,000 times. Extremely high B19V loads were observed in subjects with aplastic crisis. This study is the first large scale report of studies of the B19V
DNA loads in subjects with
erythema infectiosum and aplastic crisis, the most common and significant clinical manifestations by B19V
infections.