Snakebite in Nepal: Venomous Species, Terai Burden, Antivenom & First Aid

Snakebite envenoming (Nepali: sarpa dasne) is one of the most under-recognised rural killers in Nepal, and since 2017 the World Health Organization (WHO) has classified it as a priority neglected tropical disease (NTD). It is fundamentally a disease of poverty: it strikes farmers, herders, plantation workers and children in the agricultural lowlands, often at night, and most deaths occur at home or on the way to hospital rather than in a treatment centre.

The WHO's long-standing estimate, cited in Nepal's national guidelines, is that around 20,000 people are bitten by snakes in Nepal each year, resulting in over 1,000 deaths. More recent community research suggests the true toll is considerably higher, because most bites never reach the formal health system and are absent from hospital records. A large part of the mortality is preventable: many victims die because families first turn to traditional faith healers (dhami-jhankri), apply harmful tourniquets, or cannot reach antivenom in time.

Nepal has adopted the WHO global target of halving snakebite deaths and disability by 2030 (roughly Bikram Sambat 2087). The Epidemiology and Disease Control Division (EDCD) of the Ministry of Health and Population coordinates the national response, supplying antivenom and issuing the treatment protocol that hospitals across the country follow.

The overwhelming majority of dangerous snakebites in Nepal happen in the Terai, the hot, low-lying plains along the southern border with India. The Terai's warm climate, monsoon rains, dense rodent populations and intensive farming create an ideal habitat where snakes and people constantly cross paths. Open-style housing and the habit of sleeping on the floor expose villagers to nocturnal snakes, especially kraits, which enter homes at night hunting rodents.

A landmark multicluster random survey published in The Lancet Global Health in March 2022 (data collected November 2018 to May 2019) measured the burden directly in the community rather than in hospitals. It found an adjusted annual incidence of about 251 snakebites per 100,000 people, an envenoming rate of 49%, and a case-fatality rate of 7.8%. Extrapolated across the rural Terai, this implies roughly 27,000 to 38,000 bites and about 2,400 to 3,200 deaths every year, commonly summarised as around 2,700 deaths annually.

The dead are disproportionately children and women. A study of news-media-reported envenomings from 2010 to 2022 found a median victim age of about 19 years, with children under 18 making up nearly half of cases, and districts such as Saptari, Mahottari, Rautahat, Dang and Kanchanpur among the worst affected. Because many rural bites are never reported, official statistics almost certainly understate the real burden.

Of about 89 snake species recorded in Nepal, EDCD lists 17 highly venomous, front-fanged species of true medical importance. They fall into two families with very different clinical effects. The Elapidae (cobras and kraits) mainly cause neurotoxic envenoming, paralysing the muscles of the eyes, throat and chest. The Viperidae (Russell's viper and the pit vipers) mainly cause haemotoxic or local effects such as bleeding, swelling and kidney injury.

The two cobras, the common or spectacled cobra (Naja naja, goman/nag) and the monocled cobra (Naja kaouthia), bite by day and cause both paralysis and severe local tissue damage. The kraits, above all the common krait (Bungarus caeruleus, chure sarpa) but also the lesser black, greater black and banded kraits, are the most feared: they are nocturnal, enter houses, and their bite is often painless, so sleeping victims may not wake until paralysis sets in. Krait paralysis is caused by presynaptic beta-neurotoxins and responds poorly to antivenom once established, so mechanical ventilation is frequently the life-saving treatment.

Russell's viper (Daboia russelii, baghe sarpa) is the most dangerous viper in Nepal, causing painful swelling, spontaneous bleeding, incoagulable blood and acute kidney injury; it is present in only a few areas but produces severe, sometimes fatal, disease. The many green pit vipers (Trimeresurus and related genera, haryou sarpa) mostly cause painful local swelling and occasional coagulopathy but are rarely fatal. Crucially, the antivenom stocked in Nepal does NOT cover pit vipers.

Correct first aid saves lives, and Nepal's national guidelines are clear that the priorities are to reassure, immobilise and transport, not to interfere with the wound. Most suspected snakebites are from non-venomous snakes and are treatable, so the victim should be kept calm. The bitten limb should be immobilised with a splint or sling exactly as for a fracture, because any movement squeezes venom faster into the circulation through veins and lymphatics.

Speed to hospital is decisive. In one community study, about 80% of victims who died did so before ever reaching a treatment centre, so the guideline stresses getting to the nearest facility with antivenom as fast as possible. Nepal's motorcycle-volunteer programme in the eastern Terai, in which the patient is held firmly between a rider and a pillion assistant, has been shown in research to reduce snakebite deaths by cutting transport time.

Several popular practices are dangerous and must be avoided. A tight arterial tourniquet, still widely used with rope, rubber tube or cloth, does not stop venom spread and can cause gangrene and limb loss; if one has already been applied, it should only be loosened in hospital once resuscitation is ready. Cutting or sucking the bite, applying a 'snake stone' (jharmauro), electric shocks, chemicals or cow dung are all harmful and waste precious time. Rings and tight clothing should be removed, and a victim who cannot swallow should not be fed.

Antivenom is the only specific treatment for snakebite envenoming, and since its introduction case-fatality has fallen sharply. The antivenom stocked in Nepal is a polyvalent (often marketed as quadrivalent) product imported from India, effective against the Indian 'Big Four': Russell's viper, common cobra, common krait and the saw-scaled viper (the last not recorded in Nepal). It is supplied by the government free of charge to designated treatment centres. Importantly, it does not neutralise pit viper venom, so green pit viper bites are managed supportively.

Antivenom is given only when there are systemic signs of envenoming, such as drooping eyelids (ptosis), difficulty breathing, or incoagulable blood confirmed by the simple 20-minute whole blood clotting test (20WBCT), because it is scarce, costly and can cause severe allergic reactions. Nepal's protocol recommends an initial infusion of about 10 vials for neurotoxic or haemotoxic envenoming, repeated with 5 vials only if signs deteriorate; a Nepal randomised trial found a mean of roughly 12.5 vials is needed, and more than 20 vials is rarely useful.

Because anaphylaxis is common (around 80% of patients had some reaction in a Nepali trial), prophylactic subcutaneous adrenaline is given before antivenom and a loaded adrenaline syringe kept ready at the bedside. Antivenom alone cannot reverse established respiratory paralysis, so ventilatory support, whether by bag-valve-mask or a mechanical ventilator, is often what actually keeps krait- and cobra-bite victims alive until the venom effect wears off.

Antivenom and trained staff are concentrated in the Terai, close to where most bites occur. As of the mid-2020s Nepal had on the order of 100 or more designated snakebite treatment centres nationwide (reported figures include around 87 and, more recently, about 106), run by government hospitals, district and provincial hospitals, and non-governmental facilities such as Red Cross sub-centres and community treatment centres in the eastern lowlands.

Health posts and primary health-care centres are usually closest to a bite. Where antivenom is unavailable there, trained staff can start an intravenous line, give neostigmine and atropine for neurotoxic bites, support breathing, and arrange rapid referral to a centre with ventilation and, for Russell's viper cases, dialysis. Referral is indicated for patients needing respiratory support, worsening paralysis, persistent bleeding, surgery for necrosis, or acute kidney injury.

A newer challenge is that warming temperatures appear to be pushing lowland species into the hills. In response, Nepal has begun expanding snakebite treatment centres into hill districts such as Syangja, Rukum and Ramechhap, where venomous snakes were previously rare. This geographic spread means awareness and antivenom access can no longer be treated as a Terai-only concern.

Snakebite in Nepal is intensely seasonal, tracking the monsoon. Snakes emerge after hibernation and become most active in the warm, wet months, when flooding drives them out of their burrows and into fields and homes. The 2010-2022 media study found about 87% of reported envenomings occurred during the monsoon (roughly June to September, Ashad to Ashwin), with July the single worst month and more than half of bites happening at night between about 8 pm and 3 am.

Because kraits enter houses at night to hunt rodents, the most effective single prevention (sarpa dasne upaya) is to sleep off the floor under a well-tucked mosquito net; research in south-eastern Nepal showed bed nets protect against snakebite as well as against malaria and dengue. Keeping the home and yard free of rubbish, brush, wood piles and grain stores that attract rats also reduces the reasons snakes come near people.

When moving outdoors after dark or during the harvest, people should carry a torch, wear closed shoes or boots, and strike the ground ahead with a stick so snakes can move away, as snakes rarely attack unless provoked or trodden on. Hands should never be pushed blindly into holes, long grass or straw piles. Community education combining these measures with the message to reach antivenom fast is central to Nepal's plan to cut snakebite deaths by 2030.