VWF and Fever: The endothelium-tropic spotted fever rickettsia R. rickettsii (Rocky Mountain spotted fever) and R. conorii (Mediterranean spotted fever) induce a procoagulant state, with upregulation of TF [26], downregulation of TM [27] and release of both PAI-1 [28] and VWF [29] in cultured human endothelial cells.