VWF and leptospirosis: These flow cytometric findings were consistent with the observation that bleeders had the highest plasma VWF concentration (Fig 3C) and that the VWF activation factor was about twofold higher in both the bleeding and non-bleeding leptospirosis patients than in healthy controls, indicating that a higher amount of the circulating VWF was in an active, platelet-binding conformation (Fig 3D).