How Snake Venom Kills… and Saves Lives

Are you afraid of snakes? Of the 3 000 species of snakes, only around 450 are poisonous and potentially dangerous to humans. These kill around 100 000 people a year - mostly in Asia, Africa and Latin America. But their venom has also been used in  medical discoveries that can save human lives. 

Did you know? 

Poison refers to toxins that are ingested, inhaled, or absorbed by touch, such as from the skin of a poison dart frog. Venom refers to toxins injected into the body, such as by a snake’s fangs.

How does venom work? 

Snake venom is produced in the back of the snake's head in the salivary glands. Salivary glands are the parts of the head where saliva is made. To deliver venom, snakes have hollow fangs that act like hypodermic needles. When a snake bites, muscles in its head squeeze the venom glands. This pushes the liquid through its fangs muscles in its head squeeze the venom glands. This pushes the liquid through its fangs and into the flesh of its prey.

What is in snake venom? It varies from one species to the next. Sometimes, snakes of the same species that live in different locations can have slightly different venom compositions.

Once the toxins are injected, they can work in several ways depending on the type of snake. Some toxins target the nervous system. These are called neurotoxins. Neurotoxins prevent neurons in the brain from transmitting signals. This causes paralysis. Other toxins harm the circulatory system. These are called haemotoxins. Haemotoxins can cause red blood cells to burst, cause blood to clot, or severely lower blood pressure. Others toxins harm the muscular system. These are called myotoxins. Myotoxins cause tissue death in muscles and prevent muscle contraction. Another word for tissue death is necrosis.

Snake bite poisonings are called envenomings. 

Did you know? 

The longest venomous snake in the world is the king cobra. It can grow to over 4 metres long! It rarely bites, and its venom is not as toxic as that of most other cobras.

How do you treat snake bites in humans? 

Every year there are about 5.4 million snake bites. This leads to between 1.8 to 2.7 million envenomings. There are between 81 410 and 137 880 deaths. There are even more amputations and other permanent disabilities as a result. People die from snake bites most often in Asia and Africa. These places have lots of venomous snake species.  They also have lots of agricultural workers who come into contact with snakes. And often, the closest hospital might be far away. 

Medical researchers have developed antivenoms. Antivenoms contain antibodies that attack the dangerous proteins in venom. To develop an antivenom, a host animal is injected with larger and larger amounts of venom. Usually, this animal is a horse. Eventually, the horse’s immune system causes blood plasma cells to produce antibodies. The antibodies are then extracted from the host animal’s body, processed, and purified so they can be given to snakebite victims.

Different kinds of antivenom are usually specific to a single snake species or a group of related species. They can also be very expensive. For example, in the United States, patients can be charged thousands or even tens of thousands of dollars for a single vial! Most snake bites need to be treated with multiple vials.

Is snake venom ever helpful? 

Although the toxins in snake venom can hurt humans, they can also be used as medicine. For example, some snake venom affects blood pressure and blood clotting. Scientists can use this snake venom to develop new drugs to treat illnesses. In fact, the proteins in snake venom has been used to treat many conditions. Some examples are cancer, pain, high blood pressure, heart attacks, strokes, Alzheimer's disease, and Parkinson’s disease. The venom of other animals, such as spiders and scorpions, has also been used to develop important drug treatments.

How do scientists develop drugs from snake venom?

Developing new drugs from snake venom takes a lot of time, effort and money. First, the different ingredients inside snake venom are separated. This allows scientists to test and identify those with useful medical applications. For example, some ingredients might have the ability to block pain. Next, scientists try to develop a synthetic (not natural) version of the compound. They then test the compound in small doses on animals. Finally, scientists create a version of the drug for humans. They test it and make sure it’s safe. Once they are sure, they put it on the market.

Snake venom is a very powerful tool for snakes to subdue their prey, but also for doctors to treat illnesses and snake bites. The development of new antivenoms will hopefully decrease the number of people who die from snake bites. And the discovery of next-generation drugs to combat heart attacks, strokes, and even cancer may rely on hidden secrets contained in snake venom.