The small, mottled brown snake coiled up in a box may not look particularly menacing when compared to some of the larger specimens that are observing me from their glass enclosures. However, this inconspicuous saw-scaled viper is responsible for more fatalities than any other snake species in the world. This high death toll can be attributed to their abundance in various regions of Africa and Asia, but also to their aggressive nature and remarkable speed when striking, as explained by Professor Nick Casewell, who is guiding me through the Liverpool School of Tropical Medicine’s Centre for Snakebite Research & Interventions.
The centre houses around 150 of the deadliest snakes on the planet, and their venom is regularly harvested through a process known as “milking.” Surprisingly, the lethal compounds found in snake venom are being harnessed to create a variety of new, potentially life-saving medications. The scientists in Liverpool are focused not only on developing treatments for snakebites—an issue that significantly impacts low-income countries—but also for a range of unrelated medical conditions, including strokes, blood clots, and hemophilia.
The rationale behind this is that snake venom contains an impressive array of unique biochemicals, evolved over millions of years to manipulate biological systems. This manipulation aligns perfectly with the goals of medical researchers. There is a proven history of success in this approach; for instance, the popular weight-loss medications Wegovy and Mounjaro were derived from research into the saliva of Gila monsters, a venomous lizard. As Professor Casewell puts it, “You’re leveraging evolution, in a way.”
Safety Precautions
For visitors like me, the safety protocols in the snake room are manageable. I don safety goggles—necessary due to the presence of a spitting cobra that tends to target the eyes—and receive a brief safety briefing, learning that there is a slight risk of an allergic reaction to venom molecules that might be airborne.
For the scientists who extract snake venom, however, safety is paramount and relies on a meticulously rehearsed set of procedures, always executed in pairs. Professor Casewell holds the body of the snake while his colleague, herpetologist Paul Rowley, secures the head just behind the jaws, encouraging the snake to bite down on a membrane-covered container. The yellow venom drips down the sides and collects at the bottom of the container.
They proceed slowly and methodically, ensuring that at least one individual maintains control of the snake at all times. “If you rush, there’s a higher risk of being bitten,” states Professor Casewell. “There are numerous small verbal cues exchanged between you to confirm that you both understand each step of the process.”
The temperament of the snakes can vary significantly during the milking process. A fierce-looking brown cobra remains relatively calm while being handled, only raising its hood and appearing formidable once the procedure is complete, as if to assert its dominance. In contrast, a large puff adder writhes in agitation during handling, necessitating several attempts to position it correctly.
When they aren’t gripping the snake with their hands, the team employs a variety of homemade tools designed to keep the snake at a safe distance. These tools resemble long sticks with hooks or other implements at the ends.
Handling Escapes
Occasionally, a snake may manage to escape. However, this situation does not incite panic, according to Professor Casewell. The team simply steps back and uses their tools to gently secure the snake against the soft mat on the floor of the room. “The most challenging aspect involves the larger snakes, like mambas and cobras, which are incredibly swift,” he explains. Black mambas, recognized as one of the deadliest snakes, possess highly potent venom. “You might find them climbing up your hook, prompting you to drop it immediately.”
In the event of an accident, antivenom is readily available at a nearby hospital. This lifesaving treatment is created by injecting small, harmless doses of venom into sheep or horses, prompting these animals to produce antibodies against the toxic compounds, which can then be harvested from their blood.
While antivenom is a crucial resource, it does have limitations, including the need to identify the specific snake species that delivered the bite, as antivenom is tailored to each type. Additionally, it requires injection, which poses a challenge for individuals in impoverished or rural areas who may succumb to their injuries before reaching a treatment facility.
There is an urgent need for improved snakebite treatments, and this is where the Liverpool team steps in. They are working on a variety of innovative medicines, including advanced antivenoms that can effectively treat multiple snake species.
Another strategy involves developing an oral medication that can be stored and administered away from hospital environments. This is feasible because many toxins in various snake venoms contain reactive molecules with zinc at their core. The Liverpool team is investigating treatments that can bind to zinc, inhibiting the toxin’s efficacy. Their lead candidate, a medication named unithiol, is already used in lower doses to treat metal poisoning. In higher doses, it has shown to block the effects of snake venom in animal testing and recently passed an initial safety trial in humans, with tests on snakebite victims slated to begin next year.
Innovative Medical Applications
It may seem surprising that a snakebite laboratory could yield treatments for seemingly unrelated health issues, such as stroke. However, medical research has a long-standing history of transforming lethal venoms into beneficial drugs. For example, a class of blood pressure medications known as ACE inhibitors was developed from a compound found in the venom of the Brazilian Viper, which induces a drastic drop in blood pressure.
Different snake venoms exert various effects on the human body; some target nerves, while others directly degrade tissues. The Liverpool team is particularly interested in a third category of venoms that influence blood clotting. The blood clotting process is intricate and essential; while blood must flow freely throughout our veins, it must also solidify promptly at injury sites to prevent excessive bleeding.
The saw-scaled viper’s venom disrupts the clotting process, causing victims to bleed uncontrollably. Professor Casewell’s research team is focused on identifying exactly which elements of the blood-clotting cascade the venom targets. This could pave the way for treatments for conditions associated with blood clots, including strokes, heart attacks, and deep vein thrombosis.
Meanwhile, other research institutions worldwide are exploring different venoms that enhance blood clotting, which could lead to treatments for individuals experiencing excessive bleeding after surgeries or childbirth.
According to Professor Casewell, there is an increasing interest among scientists and pharmaceutical companies in the potential of venom research, as it has already resulted in a small but growing number of successful medicines. Alongside the recent surge in the use of weight-loss injections, a potent painkiller named ziconotide was discovered in the venom of cone snails. These marine creatures employ the chemical’s nerve-blocking properties to paralyze their prey. “The natural libraries of compounds that exist in animal venoms are incredibly promising for potential therapeutics,” emphasizes Professor Casewell. “For drug discovery, that’s an exhilarating starting point.”
