THE COAGULATION DEFECT AFTER ENVENOMATION BY THE BITE OF THE DUGITE (DEMANSIA NUCHALIS AFFINIS) , A WESTERN AUSTRALIAN BROWN SNAKE

The venoms of most Australian elapid snakes contain substances which clot mammalian blood. In vitro, such venoms have been found to activate human prothrombin. The effects of envenomation on blood coagulation and haemostasis might therefore be expected to resemble those of disseminated intravascular coagulation. In three patients bitten by dugites, similar coagulation defects were found: clottable fibrinogen was absent, fibrinogen degradation products were present, prothrombin times were greatly prolonged and levels of Factors II, V and VIII were reduced. Platelet counts were, however, normal. Severe thrombocytopenia is a characteristic feature of “endogenous” disseminated intravascular coagulation, but was not seen in these patients. There was also evidence of extensive lysis of circulating fibrinogen in all cases. These findings suggest that the “thrombin” produced by the venom activation may not be identical with that produced by physiological prothrombin activation.