The coagulation defect produced in three patients following the bite of the dugite (Demansia Nuchalis Affinis)

Abstract

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 3 patients bitten by dugites, there were similar coagulation defects: clottable fibrinogen was absent, fibrinogen degradation products were found, prothrombin times were greatly prolonged and levels of factors II, V and VIII were reduced. Platelet counts were, however, normal. After administration of antivenene, these abnormalities were corrected within a few days. No patient had overt bleeding. 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 suggested that the 'thrombin' produced by the venom activation may not be identical with that produced by physiological prothrombin activation.