Detection of Human parvovirus B19 (HPVB19) in serum samples from fever-rash ill individuals during the rubella outbreak (2005) in Bulgaria

The present study aimed to determine the involvement of the parvovirus B19 (HPVB19) as an etiological agent in individuals with fever-rash infections but not infected with rubella during the rubella outbreak (2005) in Bulgaria. A total of 194 serum samples with negative results for measles and rubella-specific IgM antibodies were tested in the National Reference Laboratory. The individuals aged 5–52 years (mean age 17.2 ± 10.15) were divided into four age groups: 5–14; 15–24; 25–34; and 35+ years old. Serological (indirect enzyme immunoassay – EIA) and molecular (extraction and detection of HPVB19-DNA) methods were used. A genotyping assay of the NS1-PCR product was proceeded with the MfeI restriction enzyme. Out of the total number of samples, 95 samples (48.97%) tested positive for HPVB19-IgM and 109 (56.18%) for HPVB19-DNA. The results from the genotyping assay revealed that genotype 1 (prototype B19) was dominant in 106 from 109 samples (97.25%), while genotype 3 (prototype V9) was detected in only 3 (2.75%). Subjects whose sera tested positive for IgM and had a positive PCR result formed a group that was most frequently linked (in 40% of cases) to acute infection. The highest prevalence was established in the group of the school-age children (5–14 years). The combined application of serological and molecular methods confirms the etiological role of HPVB19, and including virus genotyping, confirms the involvement of HPVB19 in the etiological palette of febrile rash diseases and provides a correct differential diagnostic approach.