An estimated about 5.4 million snakebites occur every year throughout the world, with 1.8- 2.7 million cases poisoning. The poisonous snakebites cause from 81,000 to 138,000 deaths each year globally. Besides, hundreds of thousands of amputations and other permanent disabilities occur due to snakebites worldwide (WHO, 2019). Hundreds of people die of snake bites annually in Nepal as well. With the monsoon season, snakes come out of their habitat and many times confront humans resulting in bites. Most of the bites are reported by nonvenomous snakes and even as many as 40 per cent bites inflicted by venomous snakes are “dry bites” meaning that they do not produce signs of envenoming. Snakebites and the major envenomation are one of the serious public health problems in Nepal as in other countries of Africa, Asia, and Latin America. Snakebite is a common occupational hazard for most at-risk groups such as farmers, and plantation workers and it results in hundreds of thousands of deaths and permanent physical disabilities. However, females and children are also at risk of envenomation. Considering those experiences from around the world, snakebite was included in the WHO’s list of neglected tropical diseases in early 2009. At present, the species of venomous snakes responsible for such bites, the nature of their venoms, and the clinical effects of envenoming in humans are known to a great extent.
Poisonous snakes About 89 species of snakes have been recorded from Nepal but the exact number of species is still not confirmed due to great diversities in the country's topography and climate. Of those, 17 species are highly venomous and dangerous. Such snakes are found mainly in the Terai region (plain land) but also in hilly areas. The venomous snakes found in Nepal can be subdivided into: Elapidae which consists of Bungarinae (Kraits, Cobras) and Elapinae (Coral snakes) and Viperidae: Viperinae (pit-less or true vipers) and Crotalinae (pit vipers) in the family. Among them, the principal, common and dangerously venomous snakes are Common Cobra (Najanaja), King Cobra (Ophiophagus Hannah), Common Krait (Bungaruscaeruleus), Banded Krait (Bungarusfasciatus) and Russell’s Viper (Daboia Russell). These five species are highly poisonous snakes found in Nepal. Owing to the poor surveillance system, the exact epidemiological data is often difficult to obtain which grossly undermines antidotes needed to manage those cases year-round. Snakebites occur in all parts of the country but bites mainly occur in the Terai and mid-hill regions where climate favours their inhabitation. Despite a scarcity of epidemiological data, the available statistics indicate victims of envenomation are male of around 25 years of age, and bites mainly occur during the evening between 5-8pm. The studies based on hospital registry analysis showed that most of the bites are inflicted by Cobra followed by Krait. It is often difficult for us to distinguish between poisonous and non-poisonous snakes, thus it is important to consider every bite as venomous. The effects of snakebites range from local pain and tissue damage to swelling, blistering, and necrosis at the bite sites. Snake venom from Veparide such as pit vipers can cause coagulopathy and platelet dysfunction which leads to spontaneous systemic hemorrhages and persistent bleeding from fang marks, wounds, or gums. Venoms from Russell vipers can cause local swelling and hemorrhagic disturbances and may also cause acute renal failure and neurotoxicity. Cobra and Krait envenoming causes neurotoxic signs and also may cause respiratory failure within half an hour of the bite. Krait bite envenoming is often associated with a delayed onset and prolonged total period of paralysis. Snakebites are not always toxic and more than one-third of the bites by even poisonous snakes are venom less. If you are bitten by snakes, first and most important act is not to get panicked. Second is to call for assistance and remove anything tight from the bitten site and avoid traditional first aid methods, herbal drugs, and other unproven remedies and try to reach health centres nearby as soon as possible where most effective and life-saving anti-snake venom is available. Preventive measures The most important first aid measure is to assure victims remain calm and immobilise the bitten area. Every year many people die before reaching the hospital as they are transported keeping flat on the backs which causes upper airway obstructed due to vomiting or paralysis of the muscle of the tongue. Therefore, keeping the victim on the left side with mouth turned down while taking to hospital reduces the risk largely. Once the victim reaches the health centre and if there is a sign of envenomation, aggressive treatment with anti-snake venom and symptomatic and supportive care save a life. Preventive measures such as wearing boots and long pants, carrying torchlight and sticks during the night, not throwing rubbish nearby houses, keeping plants away from doors and windows, and sleeping under mosquito nets will reduce the chances of snakebites significantly. As snakes are attracted to rats, people should make sure that there are no rats in and around their houses. Snakes only attack when they feel threatened; therefore they should be allowed for safe passage and should not be harassed. It is not possible to eliminate snakebites but can be decreased, to a great extent, with the help of aggressive promotion of preventive measures and mortality can be reduced in great numbers through managing good medical services. It is important to preserve these beautiful creatures of nature but at the same time, extreme caution should be observed during this season. Lastly, the availability of the good quality anti-snake venom is critical in the management of poisonous snakebites.