DHF characterized by acute type DIC with increased vascular permeability.

: Decreases in platelet count, fibrinogen concentration, factor VIII, antithrombin III and alpha 2-antiplasmin activities, increase in FDP-D fraction, and pleural effusion were observed transiently at early fever stage of DHF at grade II, indicating DHF patients had manifestations of the acute type of DIC with increased permeability of vascular wall.