ive seen shows on animal planet where a zoo keeper got bit by a black mamba on the hand and he said it was very soft and hardly felt it.
it was a wet bit and he lived. so 100% fatal is not entirely correct.
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.[9] Being a protein of low molecular weight, the venom of the black mamba is rapid-acting. In fact, its venom is the most rapid-acting venom of any snake species[32][44] and consists mainly of highly potent neurotoxins,[4][45] it contains cardiotoxins,[38][46][47] fasciculins,[4] and calciseptine.[48] Subcutaneous LD50 values for this species' venom varies greatly. Ernst and Zug et al. 1996 gave it a value of 0.05 mg/kg,[9] Dr. Bryan Grieg Fry of the University of Queensland and Engelmann and Obst (1981) gave it a value of 0.32 mg/kg,[49][50] and Brown gave it a value of 0.12 mg/kg.[32] Although there's great variation, 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.[9][32][51][33][52] To illustrate just how toxic the venom of this species is, in 2006, a fully grown adult female elephant named Eleanor, who was a matriarch of an entire herd and was between 40 and 48 years of age[53] and weighed over 7,500 pounds, was bitten and subsequently killed by a black mamba at Samburu National Reserve in Kenya.[35] Scientists in the field shot footage of Eleanor's herd calling out in distress and making desperate attempts to get the dying elephant back onto her feet, but Eleanor succumbed to the venom and died. To date, this is the only known case in which a snake bit and killed an adult elephant.[35]
Although only 10 to 15 mg[47][54][55] is deadly to a human adult, its bite delivers about 100120 mg of venom on average,[47][54][55] but they can deliver up to over[vague] 400 mg of venom in a single bite.[54][44] Its bite is often called "the kiss of death"[56] because before antivenom was widely available, the mortality rate from a bite was 100%.[6][38][33][6][51][56][57] Severe black mamba envenomation can potentially kill a human within 20 minutes or less[6][32][54][58] depending on the nature of the bite and the area bitten, but death usually occurs after 3060 minutes on average, sometimes taking up to three hours.[17][32] British wildlife enthusiast Nathan Layton was bitten in Hoedspruit, a small town near Kruger National Park, by a juvenile black mamba and died less than 30 minutes after being bitten. Nearby ambulance personnel were called to the scene, but Mr. Layton was already dead by the time they had arrived.[59][60] The fatality duration and rate depend on various factors, such as the health, size, age, psychological state of the human, the penetration of one or both fangs from the snake, amount of venom injected, location of the bite, and proximity to major blood vessels.[6] The health of the snake and the interval since it last used its venom mechanism is important. Presently, there is a polyvalent antivenom produced by the South African Institute for Medical Research (SAIMR) to treat all black mamba bites from different localities.[16][33]
If bitten, neurological, respiratory, and cardiovascular symptoms rapidly begin to manifest, usually within five minutes or less.[32] Common symptoms for which to watch are rapid onset of dizziness, drowsiness, coughing or difficulty breathing, convulsions, and an erratic heartbeat.[33] 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.[33] In cases where the victim has received larger amounts of venom than average (over 200 mg +) or the venom was delivered right into a vein, death can result within as little as 10 minutes[6][58] from respiratory or cardiac arrest.[33] This is true if the victim is bitten in the face or chest area, as 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.[44] The venom of this species has been known to cause permanent paralysis if treatment with antivenom was delayed.[33] Death is due to suffocation resulting from paralysis of the respiratory muscles.[33]
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[7] tend to agree to the notion that the black mamba is the deadliest and most aggressive snake species in the world.[7][58][61] Herpetologists who share this view include Wolfgang Wüster, Charles Pitman, Ray Hunter, and Austin Stevens.[28] Nevertheless, attacks on humans by black mambas are relatively rare, as the snakes usually avoid confrontation with humans and their occurrence in highly-populated areas is not as common compared to many other African species of venomous snakes.
[edit]Toxins
Mamba venom is made up mostly of dendrotoxins (dendrotoxin-k - "Toxin K",[62] dendrotoxin-1 - "Toxin 1",[63] dendrotoxin-3 - "Toxin 3",[64] dendrotoxin-7 - "Toxin 7",[64] among others), fasciculins, and calciseptine.[48] Being a protein of low molecular weight, the venom and its constituents are able to spread extraordinarily rapidly within the bitten tissue and as a result black mamba venom is the most rapid-acting of all snake venoms.[32][44] The dendrotoxins disrupt the exogenous process of muscle contraction by means of the sodium potassium pump. Toxin K is a selective blocker of voltage-gated potassium channels,[62] Toxin 1 inhibits the K+ channels at the pre and post-synaptic level in the intestinal smooth muscle. It inhibits Ca2+-sensitive K+ channels from rat skeletal muscle incorporated into planar bilayers (Kd = 90 nM in 50 mM KCl),[63] Toxin 3 inhibits M4 receptors, while Toxin 7 inhibits M1 receptors.[64] The calciseptine is a 60 amino acid peptide which acts as a smooth muscle relaxant and an inhibitor of cardiac contractions. It blocks K+ induced contraction in aortic smooth muscle and it blocks spontaneous contraction of uterine muscle and portal vein.[54][48] The venom is highly specific and virulently toxic. In one experiment, the death time of a mouse after subcutaneous injection of some toxins studied, was around 7 minutes. However, black mamba venom can kill a mouse after 4.5 minutes.[58]