Toxicity of the Principal Snake Venoms of Brazil

Abstract
Summary The toxicity of 12 Brazilian and 10 nearctic and Asiatic snake venoms was examined in 1790 subcutaneous mouse tests. The mean lethal doses were determined by planimetric evaluation of the mortality curves in their whole lengths. Among the venom samples examined, those of the tropical rattlesnake (Crotalus terrificus) and the coral snake (Micrurus frontalis) were, with mean lethal doses of 0.0006 and 0.002 mg. per gram of mouse, the most toxic, whereas that of the much feared bushmaster (Lachesis muta), with a mean lethal dose of about 0.037 mg./g., ranged last. It is evident from the observations and considerations presented in this paper that there exists a marked variation among the individual venoms of the same species, and that even samples collected from a large number of specimens may vary widely from other venom batches obtained from the same species in the same way. With the exception of C. terrificus and M. frontalis, all the venoms here examined exhibited a very powerful local action, provoking extensive hemorrhage, gangrene and subsequent necrosis. Figures computed from the frequency of the species and the toxicity of their venoms indicate that the tropical rattler is by far the most dangerous snake is Brazil, but that the rôle of the second in place, Bothrops jararaca, is still important, whereas the combined total of the other species will only be responsible for less than five per cent of grave snake bite accidents in this country.

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