Snake bites and antivenom

An employee at the Queen Saovabha Memorial Institute's snake farm demonstrate how to extract a snake's venom.SOMCHAI LAOPAISARNTAKSIN

Dos and Don'ts for snake bites

The dos

Remain calm. My students (who always test-read my articles) think this suggestion is quite silly. Who can remain calm just after you've been bitten by a snake, the ask? Well, if you don't control your excitement, your heart and blood circulation rate will increase and that will spread the venom through your body much faster.

Make the victim comfortable, reassure them that death is not imminent and that medical care is (or will soon be) available. Clean the wound to avoid bacterial infection. Remove all rings, watches, jewelry and shoes as they may act as a tourniquet in the event swelling occurs.

Venom travels through the lymphatic system, so the spread of the venom can be slowed by a bandage. Don't put it on too tightly, however, as it may also act as a tourniquet.

Immobilize the victim's limb. Immobilize the limb (usually a foot or hand) and bandage it using a crepe bandage (or whatever cloth material is available). Wrap the limb from the bite site to above the elbow or knee. Finally, apply a splint, and do not allow the limb or the muscles in the area of the bite to be moved much.

Get the victim to the nearest hospital for antivenom.

The don'ts

Don't use a tourniquet (something that will cut off circulation to the infected area) as it may lead to unnecessary amputation and increased trauma.

Don't bite, cut or (unlike in Hollywood movies) try to "suck out the poison", as this may cause more trauma and put the victim in shock.

Don't give the victim alcohol or coffee.

Don't try to kill or pursue the snake, as it may lead to more bites!

A rough guide to poisonous snakes in Thailand and initial treatment for snake bites

I received many letters and emails from readers who wanted to know more about snakes in Thailand and especially about snake bites and what to do if bitten. Thanks for all the interest and here's my response.

The chances of being bitten by a snake are extremely remote, but they increase when people try to kill them, catch them or use them in shows. So unless you do one of these, you are pretty safe. I have been bitten by pythons. They have hundreds of sharp teeth and the bite is painful; but since they aren't venomous, the worst that can happen is a bacterial infection.

The majority of snake bites each year occur in Asia. India consistently has the highest number of deaths by snake bites, over 20 thousand each year. One reason is India's dense population competes daily with wildlife for territorial space.

Snake varieties

There are basically four main groups of land snakes.

Elapids have front, fixed fangs and are the most venomous snakes in the world, with the most toxic being Australia's inland taipan, Oxyuranus microlepidotus.

Vipers have front, hinged fangs. The Gaboon Viper from Africa, Bitis gabonica, has the longest fangs of any snake.

Instead of fangs, Pythons have lots of teeth, and are the longest and heaviest snakes in the world, Python reticulates.

Colubrids are back-fanged snakes and are by far the most diverse and numerous of all snakes. Most colubrids are not harmful to humans, so this article is concerned only with elapids and vipers.

Venom and vipers

Snake venom is a complex type of saliva which is produced and stored in glands under and behind the eye. It varies in protein and toxicity.

There are four types of venom: haemotoxic, which attacks the blood; neurotoxic, which attacks the nervous system and causes paralysis; myotoxic, which destroys muscle tissue; and cytotoxic, which destroys other cells in the body.

The venom of elapids, such as cobras and kraits, is the most toxic, and therefore the most deadly. Left untreated, after the venom from their bite enters a victim's body, the victim's lips will tingle and their muscles will soon become paralyzed. It becomes difficult for the victim to breathe, as his vision blurs and his speech slurs. Soon his breathing will completely stop and he will die. In contrast, a cobra's bite quickly kills the tissue around the bite and causes great pain and swelling.

In Thailand vipers, such as the white lipped green tree viper (Trimeresurus albolabris) and the Malayan pit viper (Tropidolaemus wagleri) are responsible for most snake bites. It's good to know that although viper bites are very painful and soon become scary to look at, the venom is a lot slower to act and therefore less likely to be fatal, compared to the venom from elapids.

What to do if a snake bites

Opinions conflict about what course to take in the event of a snake bite. The following advice is sort of the ``best of all worlds'' and is consistent with the opinions of Dr Visith Sitprija, the director of the Red Cross Snake Farm on Rama 4 Road, an expert in toxicology. Although the snake farm does not treat snake bite patients directly (they are mostly treated at Chulalongkorn hospital), they do make the antivenom that is so critical in treating snake bites.

Antivenom is produced by injecting horses with small quantities of snake venom. The horse will build up immunity to the venom, and then the antibodies are extracted and purified to make antivenom. The Catch-22 with antivenom is that many people are allergic to it and this can be more lethal to the victim than the actual snake venom! The Thai Red Cross purifies its venom, which reduces the risk of side effects.

Every snake bite, whether venomous or not, should be treated as potentially dangerous because positive identification of the snake is often difficult, and therefore it is difficult to tell whether the snake is venomous or not. Also, some effects of a snake bite may not arise for hours or days after the bite, so getting immediately to a hospital must be a priority.

Conclusion

Remember to keep the patient calm, follow the basic instructions above and get the bitten person to a hospital. And thanks to the good works of the people at the Red Cross Snake Farm and their antivenom, the victim's chances of recovery are extremely high.

David Canavan has an MSc in Behavioral Ecology and teaches science, math and ICT at Garden International School. David is fascinated by science and loves animals, especially the dangerous kind; the more dangerous the better. You may contact David at davidc@gardenbangkok.com .

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