Zootoxin – Venom of the King Cobra
Introduction
Zootoxins are natural toxins produced by venomous or poisonous animals. Poisons exert their adverse effects when the animals’ tissues come into contact with other animals, whereas venom is most commonly exposed through bites or stings. For it is abundant all over the kingdoms of living organisms and highly specialized, zootoxin is considered a major cause for livestock and human poisoning. Regarding the toxicity of venoms, those produced by the King Cobra has its reputation as one of the most dangerous toxins.
King Cobra
Renowned for its enormous size and potency, King Cobra is endemic to Asia and can be as long as 5.5 meters, with the average individuals extending from 3 to 4 meters in length. The color of this animal can range from olive green to black, often with lighter bands or chevrons. Their natural habitats are forest, swamps and grasslands, and they are both arboreal and terrestrial.
Venom of King Cobra
The venom of King Cobra is produced in the postorbital venom glands, and its major components are three-finger toxins (3FTx) and snake venom metalloproteinases (SVMPs). Among all the types of 3FTx,the alpha-neurotoxins are the predominant and most lethal components, while cytotoxins and beta-cardiotoxins also exhibit their toxicity. The second most abundant protein family within this venom is SVMPs, which potentially lead to vascular damage and interference with haemostasis, leading to bleeding and coagulopathy.
Mechanism of action
Neurotoxic effect
Presynaptic neurotoxins
Some of the toxins, for example Ophiotoxins, affect the nerve terminal by interfering with the release of neurotransmitters into the synaptic cleft. A notable type of those whose release is blocked is Acetylcholine. As a result of the blockage, nerve signals cannot be transmitted to muscle, leading to paralysis.
Postsynaptic neurotoxins
The toxins disrupt the binding of neurotransmitters to the receptors on the postsynaptic membrane, which impair the ability of muscle to receive signals from the nervous system. Consequently, the muscles weaken, and this can potentially lead to paralysis.
Enzymatic components
Phospholipase
The enzyme called phospholipase catalyzes the process of breaking down the phospholipid bilayers of cell membranes, leading to cell lysis and inflammation at the tissue bitten. Severe pain and damage are common consequences.
Protease
Proteases are catalytic chemicals that degrade proteins, and some of the proteins are involved in blood clotting or cellular structures. This contributes to hemorrhage (bleeding) and further tissue damage by interfering with normal clotting processes and damaging blood vessels.
Hemotoxic Effects:
Despite being less abundant than neurotoxins in king cobra venom, some hemotoxins can affect blood clotting and vascular integrity, which potentially lead to hemorrhage and other circulatory disturbances.
Symptoms of King Cobra envenomation
Local symptoms immediately after the bite include discolouration of skin, edema and pain. If the cases exacerbate, swelling and necrosis accompanied by tissue sloughing may require amputation to tackle. As the neurotoxins attack the central nervous system, patients can undergo blurred vision, vertigo, drowsiness, and paralysis eventually. If the venom is not removed promptly, it will potentially lead to cardiovascular collapse and, subsequently, coma. Follow up are lethal conditions of respiratory failure and organs failure.
Treatment
The first aid for a King Cobra’s bite is to immobilize the injured body part and avoid exerting any pressure onto that area to slow down the spread of the venom. After that, it is vital to give the patient antivenom promptly, mostly through injections. This reduces the adverse effect by partially neutralizing the toxins.
Real-life cases
In the Philippines, a 46-year-old woman was bitten by a King Cobra on her thigh and passed away 2 hours 30 minutes after the envenomation due to the lack of antivenom in the local area.
Another case in the Netherlands was reported about a young man who was working in the zoo was bitten on his index finger despite wearing protective gloves. The injury was not lethal, fortunately, but he developed a gangrene and required a ray amputation.
Prevention
In order to avoid the presence of King Cobra in the garden, bushy areas should be cleared out regularly. If you see one in front of you, avoid making contact with it and move away slowly, and you mustn’t try to agitate the snake as this can provoke a bite. Always wear protective clothing when dealing with King Cobra to minimize the risk of being bitten.
Sources:
1. https://en.wikipedia.org/wiki/King_cobra#Clinical_management
2. https://www.sciencedirect.com/science/article/abs/pii/S0041010124003234
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