Epidemiology of systemic vasculitis.

The systemic vasculitides are heterogeneous conditions of unknown etiology characterized by inflammation and necrosis of different sized blood vessels. Wegener's Granulomatosis, microscopic polyangiitis, and Churg Strauss syndrome are associated with anti-neutrophil cytoplasmic antibodies and affect small and medium blood vessels. They are very rare in childhood and peak in the 65 to 70 year old age group. Wegener's Granulomatosis appears to be more common in the North of Europe compared with the South. All are more common in whites compared with other populations. Genetic and environmental factors, including infection, drugs, and silica, are important in etiology. Giant cell arteritis is predominantly a disease of whites over the age of 50. It appears more common in individuals with Nordic descent. Incidence may be increasing over time and cyclical variation in disease may reflect an infectious etiology. Takayasu arteritis is a disease of the aorta and its branches, however pulmonary and cardiac arteries may be involved. Patients are usually under 40-years of age at presentation and there are no apparent differences in incidence or clinical characteristics/aortic involvement across the globe. Kawasaki disease (KD) and Henoch-Schonlein purpura are diseases of children and rarely affect adults. Both have been reported to be more common in Asians than whites. The incidence of KD is higher in Japan and China compared with other regions. No definite trigger factors have been found, but KD has been linked to infection, house dust mite and chemicals, and Henoch-Schonlein purpura to a pesticide and drugs.