Reinfection with Chlamydia pneumoniae may induce isolated and systemic vasculitis in small and large vessels.

It is a common clinical experience that the onset of the so called non infectious vasculitides is often preceded by upper respiratory tract symptoms. A specific agent is only occasionally recovered. We report five cases in Sweden with manifestations of vasculitis from different organs. In three of the five patients the onset was preceded by upper respiratory tract symptoms. All patients had serologic findings indicating Chlamydia pneumoniae infection and all required corticosteroid treatment for symptomatic recovery. One was diagnosed as an aseptic meningitis. Another was diagnosed as a cerebral arteritis, probably a variant of a giant cell arteritis. A third patient had symptoms similar to a polymyalgia rheumatica engaging the thighs. Two patients had an acute myocardial infarction. One of them had Cogan's syndrome. The other also had pulmonary and hepatic engagement and an elevated level of anti basement membrane IgM antibodies, though not to the Goodpasture antigen. He had no renal involvement. The diagnosis of Chlamydia pneumoniae infection was based on the detection of species-specific IgA, IgG and IgM antibodies to Chlamydia pneumoniae using microimmunofluorescence technique, MIF. Four of the 5 cases exhibited a fourfold increase in antibody titers, and the fifth case was found to have high levels of IgG and IgA antibodies, suggesting recent infection. Investigations for other infectious agents were negative in all patients. The serologic findings in those patients are consistent with a pattern of reinfection with Chlamydia pneumoniae. We therefore suggest that reinfection with Chlamydia pneumoniae may induce isolated and systemic vasculitis in virtually any organ of the body.