Draibe J, et al. - Researchers carried out this work to study seasonal variations in anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) with respect to renal affectation diagnosed in Catalonia, Spain. Here, the seasonal periodicity of AAV was confirmed. A higher incidence was observed in the winter, as formerly described in the literature for other regions. This finding could be explained by an environmental factor, likely one that is infectious.