Managing Snakebite Envenomation: Global Impact, Indian Trends, and Effective Strategies
Abhishek Verma1, Bhavana Salvi1,
1Department of Veterinary Surgery and Radiology,
Arawali Veterinary College, Sikar, Rajasthan
Email id: abhishek.verma164@gmail.com
Abstract
Snakebite envenomation annually claims 100,000 lives globally, affecting over 400,000 people. India sees 1.4 to 2.8 million incidents yearly, with cobras, kraits, and vipers prevalent. Cobra and krait venom contain neurotoxins, while viper venom has cytolytic and haemorrhagic components. Management involves first aid, supportive therapy, and anti-snake venom. Traditional methods like incisions, venom suction, tight bands, and ice packs are discouraged due to harm and delays. This text discusses snakebite envenomation in animals and necessary management approaches.
Introduction
Each year, snakebite envenomation (referred to hereafter as snakebite) claims the lives of over 100,000 people and disables more than 400,000 worldwide (Gutiérrez et al., 2017). In India, the country bearing the greatest burden of snakebites globally, there are between 1.4 million and 2.8 million incidents annually, resulting in a minimum of 46,000 fatalities (Mohapatra et al., 2011). Despite its immense impact, snakebite has been notably overlooked and excluded from major global health initiatives that address both human and animal diseases.
Following the World Health Assembly in May 2017, snakebite was officially categorized as a Neglected Tropical Disease by the World Health Organization (WHO). In May 2019, the WHO introduced a formal roadmap aimed at reducing snakebite fatalities and disabilities by 50% before 2030. Although snakebite can occur across various animals, dogs and horses are the most frequently reported victims (Garg, 2000). However, the extent of snakebite in domestic animals remains unclear due to the lack of comprehensive assessments at national, regional, or global levels. Understanding the impact of snakebites on animals is vital for rural communities’ economic and social well-being, necessitating urgent attention due to potential adverse consequences. In dogs, cats, horses, and other livestock, specific body parts are commonly targeted by snakebites, highlighting the need for targeted preventive measures.
Types of snakes and their venom
Several snake species exist, but only a select few are venomous. In India, prevalent poisonous snakes include the cobra, krait, and viper. Snake venoms fall into two categories. One type contains neurotoxins, impacting the nervous system, found in cobras and kraits. The other type comprises cytolytic and haemorrhagic components, affecting the cardiovascular system, seen in vipers. (Venugopal, 2017)
Diagnosis and clinical signs
The diagnosis of snakebite depended on clinical signs indicative of envenomation from local snake species, alongside other criteria. These criteria included signs of contact with a snake, presence of puncture wounds, possible exposure circumstances (like warm weather or wooded regions), laboratory findings, and ruling out alternative diagnoses. However, diagnosing snakebites in animals, especially without a history of snakebite or clear fang marks, can be challenging.
Lab tests
- The 20-minute whole blood clotting test (20 WBCT) serves to detect coagulopathy, aiding in diagnosing viper envenomation and ruling out elapid bites. Failure to clot within 20 minutes indicates coagulopathy, confirming viper bite.
- Enzyme-linked immunosorbent assay (ELISA) identifies involved species through venom antigens.
- Hemogram may show transient haemoglobin elevation from haemoconcentration due to increased capillary leak or anaemia, especially in viper bites from haemolysis.
- Serum creatinine is crucial to exclude renal failure post-viper and sea snake bites. Elevated serum amylase and creatinine phosphokinase (CPK) levels imply muscle damage, with renal damage potential.
- Prothrombin time (PT) and activated partial thromboplastin time (aPTT) may prolong in viper bites.
- Arterial blood gas and electrolyte determinations are vital for patients with systemic symptoms.
- Urine examination can uncover haematuria, proteinuria, haemoglobinuria, or myoglobinuria.
Clinical signs
Envenomation of domestic animals by snakes’ results in a combination of local and systemic clinical signs, which vary significantly depending on the snake species and the affected animal. The bite of a cobra or krait typically induces severe pain and localized swelling, with tissue necrosis often initiating within 48 hours. Additional symptoms may include muscular weakness, difficulty swallowing, eye closure inability, and excessive salivation. Respiratory paralysis may subsequently occur due to suppression of the respiratory centre, with allergic reactions like urticaria also possible. Cobra bites usually involve minimal haemolysis. Viper venom affects the cardiovascular system, causing intravascular coagulation, blood extravasation from capillary dilation, and haemolysis. Convulsions may arise from cerebral cortex haemorrhaging. Fatal outcomes result from circulation disruption, pulmonary embolism, and asphyxia. Locally, symptoms include pain, swelling, thrombosis, and tissue necrosis. Post-mortem examination typically reveals haemorrhagic elements, infarctions, and blood in serous cavities. (Venugopal, 2017).
Management
First aid
The main goal of first aid is to slow down venom absorption and prevent severe complications by quickly getting the victim to a medical facility. Traditional methods like incisions, suctioning, tight bands, and ice packs aren’t recommended as they can worsen the situation and delay medical care. Interfering with the wound, including incisions, suction, and washing, increases infection risk and venom absorption.
The latest recommendations for first aid include reassuring the victim, as many snakebites are nonvenomous and a significant portion of venomous bites result in dry bites. Additionally, immobilizing the affected limb using a bandage or clothing to secure a splint is advised to prevent tight arterial compression. Promptly transferring the victim to a hospital is crucial. Snake bite treatment involves a combination of supportive measures such as intravenous fluid therapy, corticosteroids, broad-spectrum antibiotics, analgesics, atropine, furosemide, antihistamines, oxygen, and mechanical ventilation. The wound is cleaned with potassium permanganate solution and treated based on general principles. Animals bitten near the muzzle, such as horses and camels, may experience swelling in the head area, necessitating airway support like nasal intubation or tracheostomy.
Antivenom is administered to various animals, including dogs, cats, goats, chickens, horses, cows, and camels. It can be species-specific or effective against multiple species. In India, it’s produced by institutions like the central research institute in Kasauli, HP, Haffkine Corporation in Mumbai, Serum Institute of India Ltd. in Pune, and Bharat Serum and Vaccine Ltd. Ideally, antivenom should be given within 4 hours of a snakebite, but remains effective within 24 hours. Dosage varies based on envenomation severity and can be administered slowly via intravenous injection or infusion. The recommended dosage is typically calculated at a rate of 2 ml per minute, or by intravenous infusion with the antivenom diluted in 5–10 ml per kilogram body weight of normal saline or D5 W, infused over 1 hour. Local administration at the bite site is discouraged due to lack of efficacy and risks. Intramuscular injections are not recommended due to slow absorption and poor bioavailability compared to intravenous administration.
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