Echis - Venom

Venom

The venom of Echis species consists mostly of haemotoxin. The genus is recognized as medically significant in many tropical rural areas. They are widespread and live in areas lacking modern medical facilities. Most victims are bitten after dark when these snakes are active.

Most of these species have venom that contains factors that can cause a consumption coagulopathy and defibrination, which may persist for days to weeks. This may result in bleeding anywhere in the body, including the possibility of an intracranial hemorrhage. The latter classically occurs a few days following the bite.

Venom toxicity varies among the different species, geographic locations, individual specimens, sexes, over the seasons, different milkings, and, of course, the method of injection (subcutaneous, intramuscular, or intravenous). Consequently, the LD₅₀ values for Echis venoms differ significantly. In mice, the intravenous LD₅₀ ranges from 2.3 mg/kg (U.S. Navy, 1991) to 24.1 mg/kg (Christensen, 1955) to 0.44-0.48 mg/kg (Cloudsley-Thompson, 1988). In humans, the lethal dose is estimated to be 3–5 mg (Minton, 1967). Venom from females was more than twice as toxic on average than venom from males.

The amount of venom produced also varies. Reported yields include 20–35 mg of dried venom from specimens 41–56 cm in length, 6–48 mg (16 mg average) from Iranian specimens and 13–35 mg of dried venom from animals from various other localities. Yield varies seasonally, as well as between the sexes: the most venom is produced during the summer months and males produce more than females.