Snakebite in southern Africa...

Snakebites can be serious and sometimes life-threatening and require swift and appropriate treatment. The majority of victims do, however, experience a full recovery without the administration of antivenom. In many instances venomous snakes will bite in self-defence and inject no venom at all – such bites are referred to as dry bites. Another possibility is that a potentially deadly snake may inject a small amount of venom – far too little to do serious damage – and, in such instances, antivenom would not be required. Doctors need to do a thorough assessment of the condition of a snakebite victim before antivenom is administered.

Serious Versus Deadly Snakebites Roughly 11% of the 173 species of snakes in southern Africa can be considered deadly and these include mambas, cobras, the Rinkhals, Puff Adder, Gaboon Adder, Boomslang and the Twig Snake. The Mozambique Spitting Cobra accounts for the vast majority of serious bites, followed by the Puff Adder, and then the Stiletto Snake and Rhombic Night Adder. Most of the deaths resulting from snakebite in southern Africa are a result of Cape Cobra and Black Mamba bites. The vast majority of snakebite victims who are hospitalised soon after a bite, will survive. No more than 15% of snakebite victims will require antivenom.

How To Avoid Getting Bitten – Leave snakes alone and treat them with respect at all times. – Do not handle snakes, even small ones. Juvenile venomous snakes are just as dangerous as the adults. – Never tamper with a seemingly dead snake, as many have the nasty habit of playing dead when scared or threatened, only to strike out the moment an opportunity arises. – Wear boots and thick trousers or jeans if you spend a great deal of time outdoors. Hunters, hikers, birders and fishermen should consider wearing snake gaiters that protect the lower leg. – Step onto logs and rocks and never over them. Snakes often sun themselves while partially concealed under a log or rock. – Never put your hands in out-of- sight places, especially when mountain climbing. Berg Adders are known to bask on small ledges and will certainly bite if a hand suddenly appears close by. – Never walk barefoot or without a torch at night when camping or visiting facilities in the bush. Many snakes are active after sunset, and slow-moving snakes like the Puff Adder are easily trodden on. – Do not try to kill or catch a snake if you come across one. Throwing rocks or shooting at a snake is looking for trouble. Also do not attempt to catch a snake with braai tongs or pin it and grab it behind the head. Some snakes, such as the Stiletto Snake, cannot be held safely behind the head and you will certainly get bitten if you try. – In case of a snakebite emergency, do not attempt to catch or kill the snake – rather take a photograph from a safe distance to assist with identification.

Snakebite Symptoms Snakebite symptoms vary dramatically from bite to bite. Many snakebites take place so quickly that victims are not always certain that they have actually been bitten. A bite mark is seldom the characteristic two-fang puncture mark – often a bite will be from a single fang and may just be a scratch with a little bleeding.

In the event of a snakebite, the victim may have some of the following symptoms – An immediate burning pain, followed by swelling, which progresses up the limb and may affect the lymph glands (the Puff Adder and the Mozambique Spitting Cobra). – Dizziness, difficulty in swallowing and breathing, drooping eyelids and nausea (the mambas and the Cape Cobra). – Bleeding from the nose, small cuts, followed by bleeding from the mucous membranes and, after several hours, and severe internal bleeding (the Boomslang and the Twig Snake). – Shock, which can cause nausea, pain and difficulty in breathing.

In the Event of A Snakebite DO NOT… – DO NOT try to cut or suck out the venom Snake venom very quickly attaches to local tissue and is absorbed into the lymphatic system and very little venom can be removed by suction. Cutting may expose the wound to secondary infection. – DO NOT apply any electric shock therapy Electric shocks do not neutralise snake venom. – DO NOT apply a tourniquet Arterial or venous tourniquets are not advised in most bites as venom is initially transported largely through the lymphatic system and not through veins. There is little evidence that a tourniquet could be life-saving following a snakebite. – DO NOT apply ice or boiling water, lotion or potions Leave the bite site alone, except for cleaning it with cool water and applying a sterile gauze dressing. Boiling water does not denature snake venom. Do not give the victim alcohol. – DO NOT inject antivenom as a first aid measure If required, antivenom must be injected intravenously by a medical doctor in a hospital environment and usually in large quantities. Some patients have an allergic reaction to antivenom and this may result in anaphylaxis – a life-threatening condition if not treated promptly.

First Aid Measures for Snakebite – Get the victim to a hospital as soon as possible and in a safe manner Keep the number of the closest hospital (with a trauma unit) and ambulance service on your cell phone and call ahead to notify them of the emergency. The navigational App Waze is very handy – type in ‘hospital’ or ‘doctor’ and the closest facilities will be listed immediately and with details. (Download the ASI Snakes app) – Keep the victim calm and as still as possible Movement speeds up the spread of venom in the lymphatic system. Immobilise the victim, lay the victim down if possible and transport (or arrange transport) to the closest hospital. Elevate the affected limb slightly above heart level. – Remove rings and tight clothing If bitten on the hand, arm, foot, or lower leg, remove rings, bangles, bracelets, watches, anklets and any other tight jewellery, as well as tight clothing and shoes. – Apply pressure bandages If you are more than an hour or two from the closest medical facility, consider applying pressure bandages to the affected limb, but only in suspected Black Mamba or Cape Cobra bites. Please see section on Smart Bandages. IMPORTANT Do not waste valuable time applying a pressure bandage – immediately transport the patient to the nearest hospital with a trauma unit and, if possible, apply the pressure bandage whilst travelling.

Pressure Bandages Pressure immobilisation may be beneficial and inhibit the spread of venom while the victim is transported to hospital. It should not be used in spitting cobra or adder bites where excessive swelling is anticipated, but rather for bites from the Cape Cobra and Black Mamba. The idea is not to slow down blood flow, but rather to put pressure on the lymphatic system and, in doing so, reduce the rate at which venom is absorbed. The application of a pressure bandage is rather complex and requires training to get the pressure right. Ideally make use of a Smart bandage.

Application of a Pressure Bandage – Immobilise the limb and immediately apply firm pressure to the site of the bite with a hand. – Wrap the bite site tightly with a Smart bandage and continue wrapping the entire limb from the bite towards the heart. – For the pressure bandage to be most effective, it must be applied at a very specific pressure – 50 -70 mmHg on a blood pressure monitor. This is easily achieved with a Smart bandage and near impossible with a regular crepe bandage. – This is not easily achieved without proper training but, as already mentioned, it is unlikely to cause any ill effects in Black Mamba or Cape Cobra bites. – For bites on the foot or leg, once the pressure bandage has been applied properly, splint the leg to immobilise it and bind the two legs together to maximise immobilisation. – If the bite is on a hand, straighten the arm and, once the immobilisation bandages have been applied, splint the straightened arm to immobilise it. After applying the pressure bandage, check for the presence of a pulse below distal to the bandage. Check the pulse every 10-15 minutes. If the pulse is not palpable, then the pressure bandage should be removed and the need for it reassessed. – Provided there is no contraindication to it staying in place, the pressure bandages should remain in place until such time as the patient reaches a hospital and must only then be removed by a medical doctor.

Pets, Farm Animals and Snakebite Many dogs are bitten by snakes, usually while trying to kill a snake. Cats are very quick and smart enough to attack juvenile snakes only and are seldom bitten. Farm animals, including sheep, goats, horses and cows may suffer from snake bites, usually on the face or neck, and this may result in severe swelling and tissue damage.

Popular myths that are meaningless in saving your pet or farm animal after a snakebite – Forcing milk down the animal’s throat. – Feeding it charcoal. – Giving the animal Allergex tablets. – Cutting the tip of the animal’s ear to let the venom ‘bleed out’. – Injecting your horse or cow with petrol as it supposedly neutralises snake venom.

The bite from a neurotoxic snake (largely mambas and some cobras) may cause respiratory paralysis and threaten the animal’s life. Such animals may die without antivenom and/or assisted ventilation. Should the animal stop breathing on the way to a veterinarian, you can try mouth-to-nose resuscitation. These animals will probably need antivenom and will likely have to be placed on a ventilator to help them breathe while the antivenom takes effect. Bites from snakes with predominantly cytotoxic venom – such as adders and spitting cobras – result in pain, swelling and blistering and this may lead to tissue damage. Small animals may suffer severe blood loss in addition to tissue damage. In cases where dogs are bitten in the face and throat region the swelling may also inhibit breathing and this is particularly problematic in small dogs. Animals that are severely envenomated may die as a result of hypovolemic shock and/or tissue necrosis and cell death. In cases of severe envenomation, antivenom is the only solution and anything from two to six (or more) vials of polyvalent antivenom (polyvalent antivenom neutralises the venom of cobras, mambas, the Rinkhals, Puff Adder and Gaboon Adder) may be required. Such treatments cost anything from R4,000 to over R20,000. For venom in the eyes, the treatment is like that for humans. Gently rinse the eyes with water for 15 – 20 minutes and get the dog to a veterinarian who will apply local anaesthetic and antibiotic eye drops. If the correct procedures are followed, most dogs regain full sight within a few days. There is very little an owner can do to save an animal’s life that has been bitten by a venomous snake, other than getting it to a vet. Home remedies and first aid treatment has very little effect on the final outcome of such a bite.

Know Your Venom

Snake venom is complex in composition and varies dramatically from species to species. There may even be variation in the potency of venom within the same species. Snake venom is generally divided into three categories based on the toxins it contains: Neurotoxins (the mambas and several of the cobras, especially the Cape Cobra), Cytotoxins (the Puff Adder, Gaboon Adder and Mozambique Spitting Cobra), and Haemotoxins (the Boomslang and the Twig Snake).

However, these are broad categorisations and do not cover all the complexities or combinations of venom – the venom of the Forest Cobra, for example, contains a mixture of both neurotoxins and cytotoxins. So when we say that a snake has neurotoxic or cytotoxic venom, it is a generalisation and refers to the dominant clinical effects.

Neurotoxic venom affects the nervous system Symptoms may include drowsiness, vomiting, increased sweating, blurred vision, drooping eyelids, slurred speech and difficulty in swallowing, speaking, breathing and weakness of other muscle groups. The respiratory muscles are gradually paralysed which leads to respiratory failure. Snakes with predominantly neurotoxic venom include the Black Mamba, Green Mamba, and some non-spitting cobras.

Cytotoxic venom affects the tissue and muscle cells Symptoms may include immediate burning pain at the site of the bite followed by local swelling that could continue for several days. In severe cases the entire limb may swell. Local tissue necrosis is quite common and may result in the loss of a limb. Snakes with predominantly cytotoxic venom include the Puff Adder, Rhombic Night Adder, Mozambique Spitting Cobra and Stiletto Snake.

Haemotoxic venom affects the clotting mechanism of the blood There is usually little or no swelling and very little pain initially. The bite is followed by oozing of blood from the bite site after a few hours, headache, mental confusion, nausea, vomiting and increased sweating. After several hours there may be bleeding from small cuts, the mucous membranes of the mouth and nose, purple patches under the skin, and eventually severe internal bleeding which results in vomiting of blood and haemorrhage from the bowels. Kidney failure and brain haemorrhage may occur after a few days.

Emergency Numbers

If you spend a great deal of time in the bush, check whether your medical aid company provides a helicopter evacuation service in medical emergencies and record the appropriate telephone numbers.

Netcare Ambulance 082911 ER24 Ambulance 084124 Poison Information Helpline 0861 555 777 African Snakebite Institute +27 82 494 2039 Dr P.J.C. Buys (Namibia) +264 81 127 5109