Black Mamba - Venom

Venom

Among mambas, toxicity of individual specimens within the same species and subspecies can vary greatly based on several factors, including geographical region (there can be great variation in toxicity from one town or village to another) and weather. Its venom is the most rapid-acting venom of any snake species and consists mainly of highly potent neurotoxins; it also contains cardiotoxins, fasciculins, and calciseptine. Subcutaneous LD₅₀ values for this species' venom varies greatly. Ernst and Zug et al. 1996 gave it a value of 0.05 mg/kg, Engelmann and Obst (1981) gave it a value of 0.32 mg/kg, Spawls and Branch list it as 0.28 mg/kg, and Brown gave it a value of 0.12 mg/kg. Although the variation is great, the average SC value of the black mamba's venom is said to be around 0.185 mg/kg, making it one of the most venomous land snakes in the world.

Although it is estimated that only 10 to 15 mg is deadly to a human adult, its bite delivers about 100–120 mg of venom on average, but the largest record is 400 mg. Its bite is often called "the kiss of death" because, before antivenom was widely available, the mortality rate from a bite was 100%. Severe black mamba envenomation can kill a person in 30 minutes, but sometimes it takes up to 2—3 hours, depending upon many factors. British wildlife enthusiast Nathan Layton was bitten in Hoedspruit, a small town near Kruger National Park, by a juvenile black mamba and died after being bitten. Nearby ambulance personnel were called to the scene, but Mr. Layton was already dead by the time they had arrived. The fatality rate depends on various factors, such as the health, size, age, psychological state of the victim, the penetration of one or both fangs from the snake, amount of venom injected, pharmacokinetics of the venom, location of the bite, and proximity to major blood vessels. The health of the snake and the interval since it last used its venom mechanism is important. Presently, a polyvalent antivenom produced by the South African Institute for Medical Research (SAIMR) is used to treat all black mamba bites from different localities. Due to antivenom, a bite from a black mamba is no longer a certain death sentence. But in order for the antivenom therapy to be successful, vigorous antivenom therapy must be administered very rapidly post-envenomation. The doses of antivenom required are often massive (10–12 vials). Cases where 100 cm3 of antivenom required is not at all unusual.

If bitten, severe neurotoxicity often ensues. Neurological, respiratory, and cardiovascular symptoms rapidly begin to manifest, usually within ten minutes or less. Common symptoms for which to watch are rapid onset of dizziness, drowsiness, coughing or difficulty breathing, convulsions, and an erratic heartbeat. Other common symptoms which come on rapidly include neuromuscular symptoms, shock, loss of consciousness, hypotension, pallor, ataxia, excessive salivation (oral secretions may become profuse and thick), limb paralysis, nausea and vomiting, ptosis, fever, and very severe abdominal pain. Local tissue damage appears to be relatively infrequent and of minor severity in most cases of black mamba envenomation. Edema is typically minimal. A black mamba can rear up around one-third of its body from the ground, which can put it at about four feet high. When warding off a threat, the black mamba delivers multiple strikes, injecting large amounts of virulently toxic venom with each strike, often landing bites on the body or head, unlike other snakes. The venom of this species has been known to cause permanent paralysis if treatment with antivenom was delayed. Death is due to suffocation resulting from paralysis of the respiratory muscles.

Due to various factors, including the toxicity and high yield of its venom, the fact that untreated bites have a mortality rate of 100%, its high level of aggression, its speed, agility, and size, many herpetologists agree the black mamba is the deadliest and most aggressive snake species in the world. Herpetologists who share this view include Wolfgang Wüster, Charles Pitman, Johan Marais, Vivian FitzSimons, Ray Hunter, and Austin Stevens. Nevertheless, attacks on humans are relatively rare, as the snakes usually avoid confrontation with humans and their occurrence in highly populated areas is not as common as some other African species of venomous snakes.