Bitten by a snake and to reverse its venom

Rains are here, and soon snakes shall follow. This is a routine in vast swathes of rural tropics, including India. Snakes are an integral part of folklore, as well as of religious texts and mythology. There are many a temples dedicated to the “Snake Gods”, who apparently provide protection and an eternal life. Entire medical science has slithering snakes in its symbols. Yet, when it comes to people who get bitten by a snake, it is a neglected disease. This medical neglect is also reflected in philately. Further, the scientific mechanisms to reverse its venom are still limited, and fraught with uncertainties.

About 3-4 million people in India are bitten by a snake every year, and an estimated 50,000 of them die. While some intermittent programs to reduce deaths due to snake bites exist in some states, it was only last year, in 2024 did India launched a National Action Plan for Prevention and Control of Snakebite Envenoming (NAPSE) in India. This initiative aims to halve the Snakebite deaths by the year 2030. One of the medical breakthroughs that occurred about 130 years ago, was discovery of anti-snake venom. This discovery remains a mainstay in management of venomous bites till date.

Albert Calmette, Father of anti-snake Venom

Albert Calmette was a French Physician, who is better known for his discovery of a vaccine against Tuberculosis. He along with Camille Guerin discovered the BCG vaccine in 1921 (which bears names of both scientist, as BCG is called Bacillus Calmette Guerin). However, unknown to many he had also discovered the first anti-snake venom, in 1895, about 25 years before BCG became a reality.

Albert completed his medical education in 1883, and at age 20 he was serving in the French Naval corps at Hong-Kong. By the year 1890, he had also served in French West Africa, and in Atlantic islands of St Pierre and Miquelon.

After working for a few months with Louis Pasteur, he was sent in 1891 to head Pasteur Institute at Saigon (Now Ho Chi Mihn City, Vietnam). Here he studied various poisons, and presumably collected enough Cobra venom (from Indian Cobra – Naja Naja). In 1894, he moved back to France, and he took back enough venom with him.

A few years earlier, in 1887, an American physiologist, Henry Sewall had discovered that the pigeons inoculated with small doses of rattlesnake venom become immune to poisonous bites. This research led Calmette to successfully develop an anti-cobra serum. In 1894, he injected small doses of cobra venom in rabbits, and collected its serum. This serum had anti-snake venom properties. By 1895, he was able to produce larger quantities of anti-snake venom serum by inoculating horses.

Venom provides its own cure

Thus, in 1894 we had our first anti-snake venom (ASV), against Indian Cobra (Naja naja). We also discovered that ASV is species specific. Anti-venom against one species does not work against another. So over next few years, we used the same technique to produce ASV against different species across the world.

In 1901, Vital Brazil, developed the first monovalent and polyvalent antivenoms for Central and South American snakes. Vital Brazil had also trained at the Pasteur institute in Paris. Over next decade we had more anti-venoms against poisonous snakes, spiders as well as scorpions. Brazil helped establish Butantan institute in Sao Pualo, a leading global center for anti-snake venoms in Brazil.

Indian Snakes

In India 75% of venomous bites are due to either vipers (Saw scaled viper Echis carinatus, Russell’s viper Daboia russelli), Elapids (spectacled cobra or Naja naja) or Kraits (common krait Bungarus caeruleus). Hence the ASV recommended for use in India, has antivenom against these big-four snakes. This is a mix of four types of anti-venoms, each produced from horse serum.

India has more than 300 species and subspecies. About 240 of these are non-venomous. However, by sheer look it is often difficult for a lay-person to identify a poisonous snake. Further, most bites take place in the dark, and the person who is bitten could be too terrified to actually see the type of the snake. Yet, experts can identify a snake species, and categorize these as less poisonous or non-poisonous.

Prevention and treatment of snake bites

Each region of the world has many snake species, and often it is difficult to predict if the bite could be venomous. For some bites (eg elapids) the effect of venoms is rapid, and for others (eg vipers and kraits) if is rather slow. Hence, it is important that every person with a snake bite is treated in the same way. The focus of management is to immobilize the limb and transport to the hospital. Use of local (at the site of the bite) treatments is discouraged, as it is not useful, and delays definitive medical management.

The main drug against venom, is ASV. It needs to be administered in the right dose, through an intravenous injection. Since this is a purified horse-serum, reactions to ASV are usual. Hence ASV is administered slowly, with adequate precautions.

ASV needs to be tailored as per the prevalent poisonous species. Hence it needs to be locally relevant. More than 80% of the countries across the world, donot produce their own ASV. This leads to an asymmetry in supply. As this process is tedious, the global supplies of ASV are quite limited. There is a ongoing search for a universal serum, but we are not there as yet.

Complications of a Snake Bite need more technology

Management of snake-bite also requires access to technology. Victims of Neuroparalytic snake bites (eg Cobras and Kraits) often need mechanical ventilation. On the other hand victims of vasculotoxic snake bites (eg Vipers) often need renal support and hemodialysis. If we want to reduce deaths due to snake bite, facilities with these technologies should also be available. We need this technology close to the locations where more bites are anticipated. Often this is not the case, as more bites happen in remote areas, far away from city hospitals that have these lifesaving technologies.

So while challenges are many, and snake bites are expected, prevention by simple measures is another option. Wear shoes, so that you may not accidentally step barefoot on a snake. Carry a torchlight in the dark, so that you may spot one. If you spot a snake, let it go its own way. Clear the ground around the home, and trim the trees so that snakes do-not enter households. Inside the house, avoid sleeping on the floor. Some of these could work, yet we need to remember that many humans are just living a few inches above the “kingdom of the snakes”.