Vipera Aspis - Venom

Venom

A bite from this species can be more severe than from V. berus and is very painful. According to Stemmler (1971), about 4% of all untreated bites are fatal. Lombardi and Bianco (1974) mention that this species is responsible for 90% of all cases of snakebite in Italy.

The toxicity of the venom varies. Stemmler (1971) states that the population in Passwang district, Switzerland have the strongest venom based on studies conducted on mice. Compared to venoms from other species, it is relatively toxic. Brown (1973) gives LD₅₀ values of 1.0 mg/kg IV and 1.0–2.0 mg/kg SC. Tu et al. (1969) report 4.7 mg/kg IM. Venom yield is relatively low. Boquet (1964) reported a daily extraction figure of 9–10 mg.

Envenomation symptoms include rapidly spreading acute pain, followed by edema and discoloration. Severe haemorrhagic necrosis may occur within a few hours. Vision may be severely impaired, most likely due to degradation of blood and blood vessels in the eyes. The venom has both coagulant and anticoagulant effects. The venom may also affect glomerular structure, which can lead to death due to renal failure.

According to Cheymol et al. (1973), the venom does not affect neuromuscular contractions in in vitro preparations. Lack of this neurotoxic affect would indicate that fatal cases involving the cardiovascular system are the result of direct muscle injury or reduced oxygen exchange. On the other hand, Gonzalez (1991) reported that in two cases the victims developed neurotoxic symptoms, including difficulty in breathing and swallowing, as well as paralysis of the bitten limbs.