Infection‐associated vasculitides

Abstract

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.

An interesting case of small vessel pathology following coronavirus infection

“…Microbes, including bacteria, viruses, protozoa and fungi, have been incriminated in the pathogenesis of vasculitis. 1 The causal link between HCV and cryoglobulinaemic vasculitis (CV), and HBV and PAN and CV are well established. 2 These two entities are included as 'vasculitis associated with probable aetiology' in the 2012 Chapel Hill Consensus Conference on the Nomenclature of Vasculitides.…”

“…Both direct endothelial invasion and indirect autoimmune mechanisms have been postulated. 1 Coronaviruses (CoVs) are of the Coronaviridae family and are enveloped viruses with a single strand of RNA. Under electron microscopy, the virions appear as spike-like projections from the virus membrane giving the appearance of a crown.…”

“…Numerous microbial agents, including bacteria, viruses, protozoa and fungi, have been described in association with vasculitis. 1 This strong causality is well evidenced with certain types of infection such as hepatitis B virus-related polyarteritis nodosa (PAN) and hepatitis C virus-related cryoglobulinaemia, 2 3 while this association between infection and vasculitis is less robust with a wide variety of other infectious pathogens. The work-up for vasculitis is, therefore, extensive and aims to exclude other possible aetiologies of malignancy, autoimmune diseases and other infections.…”

Pulmonary manifestations of systemic vasculitis in childhood

“…Pseudomonas and Legionella infections may cause a necrotising pulmonary vasculitis if a pneumonia becomes complicated by direct infection of the pulmonary vessels [32]. Entry of pathogens into blood vessel walls may cause inflammation and immune-complex deposition, or generation of autoantibodies that trigger vasculitis.…”

Vasculitis research: Moving east

“…The first write‐up in this section is on this challenging clinical manifestation by Direskeneli's group . The last write‐up in the supplement is on infection‐associated vasculitis by Haq et al . This is of immense importance to the endemic areas.…”