Parainfluenza infection is associated with Henoch-Schönlein purpura in children

Background To investigate the association of respiratory tract viruses with Henoch-Schonlein purpura (HSP) in children. Methods 40 children with HSP and 42 controls with upper respiratory tract infections were enrolled in the study. In both groups, the serum IgM antibodies and viral antigens in peripheral blood mononuclear cells (PBMCs) of common respiratory tract viruses including parainfluenza virus (PIV), influenza, respiratory syncytial virus (RSV), and adenovirus were detected. Children with HSP nephritis (HSPN) received renal biopsy, and antigens of the aforementioned viruses were examined. Results Viral IgM antibodies in sera and antigens in PBMCs were detected in HSP and control groups (55% vs. 42.9% and 60% vs. 42.9% respectively), but the differences were not significant. The prevalence of PIV IgM antibody and antigen in PBMCs in HSP group was significantly higher than that in controls (P < 0.01). HSP children with antigens in PBMCs had higher urinary microalbumin and 24-h urinary protein than those without (P < 0.05 and P < 0.01 respectively). 22 children with HSPN received renal biopsy and 13 of them had viral antigens in the kidneys (12 for PIV and 1 for RSV). HSPN children with viral antigens in kidneys also had higher urinary microalbumin and 24-h urinary protein than those without (P < 0.05) and chiefly manifested as proteinuria (P < 0.01). However, no differences in terms of histopathological characteristics between children with or without viral antigens in the kidneys were observed. Conclusions The presence of respiratory tract viruses was common in HSP children. PIV may be an important contributing factor in the pathogenesis of HSP.