An in vitro and in vivo comparative study was performed on the effects of Crotalus durissus terrificus venoms from a mother and its 15 newborns. The venoms were tested for protein content, lethality, proteolytic, myotoxic, hemorrhagic, and phospholipase A2 activity. The minimum coagulant dose in plasma and human fibrinogen, protrhombin, and Factor II activations were analyzed. The venoms were also analyzed by polyacrylamide gel electrophoresis (PAGE). This showed that despite similar total protein content, the biological effects of the venoms were different. Venom from young snakes exhibited higher enzymatic and coagulant activities and higher myotoxicity compared to the mother’s. In addition, the PLA2 content paralleled myotoxicity. However, no difference could be detected in their toxicity (LD50 0.08 mg/Kg). High incidence of blood coagulation disorders and elevated circulating myoglobin may characterize systemic envenoming by young C. d. terrificus.

Treatment of systemic envenoming in snakebite victims has, in the past, depended almost entirely on the individual clinician's experience in assessing the severity of envenoming. The efficacy of treatment is obviously related to the neutralising potency of the antivenom used, the route by which it is administered and the dose. The use of techniques for evaluating the efficacy of antivenoms has proved to be very useful, as an adjunct to recognised clinical observations, for a more objective evaluation of antivenom efficacy and dosage. In patients bitten by many vipers, including the Brazilian pit vipers, the reversal of the venom-induced coagulopathy provides an ideal indicator as to the efficacy of an antivenom. Likewise, the development of enzyme immunoassay has permitted us to estimate levels of circulating specific venom and antivenom levels at any time after the bite in the patient's blood; the efficacy of an antivenom can thus be objectively assessed by measuring the neutralisation and clearance of venom antigen. In Brazil, it appears that clinicians treat patients with excessive amounts of highly efficient antivenoms, which results in an unacceptably high incidence of reactions. In Sri Lanka, the use of imported Indian antivenom is relatively ineffective in neutralising the procoagulant and other effects of the venoms of Sri Lankan snakes, demonstrating the real problem of venom variability within individual species. In West Africa, the improved restoration of blood coagulability, the resolution of haemorrhagic disturbances and the increased rate of clearance of venom following treatment of Echis victims with a monospecific as opposed to a polyspecific antivenom has been demonstrated, and new smaller fragment Fab antivenoms have been developed and are now under clinical assessment. Such clinically based coagulation and immunological studies should result in more efficient and controlled use of expensive antivenoms for treatment of systemic envenoming and the accurate assessment of newly designed products. Such studies also emphasise the importance of individual countries producing their own antivenoms for treatment of systemic envenoming. Likewise, the use of such objective systems now enable us to assess the use of first aid measures such as tourniquets.