[Malignant Mediterranean boutonneuse fever. Septic shock of unknown origin?].

Mediterranean Botonous Fever (MBF) is an infectious disease which provokes multisystemic vasculitis due to endothelial proliferation of rickettsia conorii. Its incidence, in our environment, has greatly increased during the last years being endemic in many large cities and their surrounding suburbs. In some cases its evolution is specially malignant resulting in septic shock, adult respiratory distress syndrome, and multiorgan failure.