Infection-associated vasculitides.

Vasculitides are disorders characterized by inflammation of the vessel walls, often caused by autoimmunity, but sometimes as a result of microbial invasion. Almost all types of microbes including bacteria, viruses, protozoa and fungi have been incriminated in the pathogenesis of vasculitis. Accurate etiological diagnosis is important since immunosuppressive treatment may lead to further deterioration if infection is the cause of vasculitis. Clinical features sometimes provide clues to the etiology. Further evaluation requires a focused and cost-effective plan of laboratory investigation. The investigations aim at establishing the diagnosis of vasculitis and identify the causative organism. An accurate diagnosis of vasculitis optimally requires histological examination and imaging. For infection-associated vasculitis, the identification of the organism requires studies of stained specimens, cultures, and/or detection of antigens and antibodies. Ideally, the treatment involves administration of an appropriate antimicrobial. In non-self-limiting types of vasculitides, glucocorticoids are needed when the symptoms are progressive, with vital organs involvement, and sometimes, when there is no antimicrobial agent of proven efficacy against the incriminated agent. Additional immunosuppressive agents or interventions must be considered when the disease is severe and/or post-infective immune mechanisms are involved in the pathogenesis, e.g., severe HBV- or HCV-associated vasculitides. Available preventative vaccinations are also crucial. The incidence of HBV-associated vasculitides dramatically decreased following HBV vaccination campaigns, and other infection-associated vasculitides may as well in the future.