Infections in vasculitis.

Infections, mainly viral, are the cause of some vasculitides, like polyarteritis nodosa (hepatitis B virus) or mixed cryoglobulinemia (hepatitis C virus), and it has been hypothesized that others might be due to infectious agents (HIV, EBV, parvovirus...). Among etiologies of vasculitis, the responsibility of a Burkholderia-like strain has been recently demonstrated as the cause of giant-cell arteritis. On the other hand, patients frequently develop infections, mainly as a consequence of steroids, immunosuppressants and most immunomodulating treatments prescribed to treat vasculitides. Infections occur when patients receive steroids and immunosuppressants, especially in the long term. They are more frequently observed in elderly patients or in patients with poor general condition. Infection risk is not reduced when biotherapies are prescribed to induce or maintain remission. Patients, considered at higher risk for infections, should be followed closely and their immunological status monitored periodically. We recommend especially to monitor neutrophiles, lymphocytes and if needed CD3-, CD4- and CD8-cell counts in patients receiving steroids and cyclophosphamide or other cytotoxic agents. In patients treated with rituximab, CD19 and gammaglobulins should be monitored regularly. Prophylaxis are needed in patients at risk to develop infections.