OBJECTIVE: To investigate the prevalence of human parvovirus B19 (B19) infection in the bone marrow of systemic sclerosis (SSc) patients.METHODS: Twenty-one consecutive SSc patients and 15 sex- and age-matched subjects without immunological rheumatic diseases were studied for: (i) the presence of circulating anti-B19 antibodies (anti-B19 IgG and IgM type and anti-B19 NS1 IgG) detected by means of standard methodologies, and (ii) B19 genomic sequences in sera and bone marrow biopsy specimens using a nested-PCR technique.RESULTS: The presence of B19 DNA was demonstrated in a significant percentage of bone marrow biopsies from SSc patients (12/21; 57%) and was never detected in the control group (p < 0.01). In no case was the B19 viremia observed, while serum anti-B19 NS1 antibodies, possible markers of B19 persistent infection, were more frequently detected in SSc patients than in controls (33% vs 13%). SSc patients with bone marrow B19 infection showed a shorter mean disease duration than B19-negative patients (5.6 +/- 4.2 vs 12.7 +/- 7.8 yrs; p < 0.01).CONCLUSIONS: This is the first demonstration of bone marrow B19 infection in a significant percentage of SSc patients. The possible etiopathogenetic role of B19 should be verified in a larger patients series and further investigated by means of molecular biology studies.