YSN-ASM Science Café KL
LURKING SNAKES ON THE RUN

On 15 August 2020, the Young Scientists Network-Academy of Sciences Malaysia (YSN-ASM) organised a Science Café Session titled Lurking Snakes on the Run. The session was moderated by Shawn Keng and featured Dr Tan Choo Hock, Senior Medical Lecturer at the Faculty of Medicine, University of Malaya. Dr Tan leads the Venom Research and Toxicology Lab (Vetox Lab) at UM’s Department of Pharmacology.

Are Snakebites Becoming More Common?

According to Dr Tan, snakebites are becoming more common. It is increasingly common to encounter snakes around the house – they could be hiding in shoes and popping up in the oddest of places such as the toilet bowl, air-conditioning vents, or even in car engines. Apart from land snakes, cases of attacks involving sea snakes were also recorded.

The factors leading to an increase in snakebite occurrences are as follows:

• Human activities: recreational (e.g.reptile shows) and occupational (e.g. firefighter handling cases of snakes found in human settlements)
• Climate change: meteorological impact e.g. heat waves and floods
• Sprawling suburbs: urbanisation leads to encroachment and destruction of snakes’ natural habitats.

In his presentation, Dr Tan illustrated the effect of urban sprawl that destroys natural habitats for the sake of urban development. This leads to animals such as snakes to be cornered and having nowhere to go, finding their way into human dwellings to find shelter and to search for food.

Dr Tan also showed climate change to have contributed to the increase in snake encounters and snakebites. Rising global temperatures and events such as floods, wildfires, drought, heatwaves, and cold spells have made snakes’ natural territories uninhabitable. The snakes either die out or they adapt by moving away, notably into human settlements, thus increasing its encounter with humans, pets, and livestock. The snakes’ migration also disturbs the ecology of the surrounding area. Dr Tan gives an example of the rise in the population of Burmese pythons in North America, thanks to its demand in the entertainment industry. Having been let loose in the wild once the owners are no longer able to care for them, these snakes were released into the wild. Having no natural predators, they are considered an invasive species, currently posing a threat to the local alligator population by preying on them.

Human and Snakes’ Relationship in Civilisation

Throughout history, snakes have played a prominent part in human civilisation. Snakes have been prominent in recorded histories and mythology. Snakes are also part of the economy, having been used for entertainment purposes and for exotic massage sessions. Snake by-products are also highly sought after; snakeskin in are in high demand to make luxury outfits shoes and bags, and snake secretions form its organs are sought after in traditional medicine as well as the cosmetics industry. Humans have also traditionally used snakes as a natural pest control for rodents. From a medical perspective, snakes have been extensively used in the discovery of novel molecules and compounds that can be medically beneficial. Dr Tan mentioned an important anti-hypertensive medication that comes from snake venom. Snake venom has also been engineered into various types of drugs such as anticoagulants to treat stroke and cardiovascular diseases.

Global View on Snakebites

Dr Tan noted that these figures might be underestimated since most snakebites are never reported, especially those from rural areas and geopolitically disadvantaged populations. One might think that living in an urban setting might exempt them from encountering snake and being afflicted by snakebites; however, that is not the case. Currently, the WHO has identified snakebites as a neglected tropical disease.

Venomous vs Non-venomous Snakes

Next, Dr Tan presented on differentiating venomous and non-venomous snakes. However, he prefaced this segment by reminding everyone to treat all encountered snakes as venomous to err on the safe side.

A trait of non-venomous snake is the position of its teeth. Non-venomous snakes such as pythons have rows of teeth that faces inwards. On the other hand, venomous snakes have forward facing fangs with which it can bite and transfer venom to incapacitate its prey.

Dr Tan also wanted to inform the audience on the difference between the terms “poisonous” and “venomous”. If you bite something and it kills you, it is poisonous; if something bites you and kills you, then it is venomous.

Dr Tan then elaborates on medically important venomous snakes. Most venomous snakes belong to the Viperidae and Elapidae families. The Viperidae family includes snakes such as vipers and pit vipers. Meanwhile, the Elapidae family includes snakes such as cobras and coral snakes (both land snakes) as well sea snakes such as sea krait.

As their name suggests, venomous snakes carry venom, a complex mixture of proteins and polypeptides that are contained in venom glands and injected into prey via the snake’s fangs. More than 90 percent of the proteins and polypeptides in venom are biologically active, meaning it can disrupt normal bodily functions by causing bleeding, paralysis, and tissue destruction. A common effect of snake venom is neurotoxicity (usually from cobras) that affects the nervous system, causing breathing difficulties; on the other hand, pit viper venom affects the blood, causing uncontrolled bleeding. Snake venom also commonly causes tissue destruction, evidently in how snakebites typically look horrid due to necrosis. Apart from this, snake venom can also affect the prey in other ways, such as causing kidney failure.

Treatment for Snakebite Envenomation

Envenomation is the process by which venom is injected by the bite or sting of a venomous animal such as snakes. Treatment can be divided into two parts: supportive treatment, which include countering the effects of snake venom with artificial ventilation or intubation; using blood transfusion to counter blood loss; skin grafting (or in severe cases, amputation) to replace destruction of skin tissue around the wound; in some cases dialysis is used to counter the effects of venom that affects the kidneys.

The definitive treatment of snake wounds involves the usage of antivenoms to neutralise snake venoms. Dr Tan pointed out that most of the antivenom products used in Malaysia are sourced from Thailand due to the similar species of snakes in both countries. Antivenoms are typically species-specific (i.e. monovalent/monospecific), meaning that they can be used effectively for one type of snakebite only. For example, an antivenom for cobras will be useless against pit viper snakebites. There are also antivenoms that works on snakebites from different species of snakes (i.e. bivalent/trivalent/polyvalent/polyspecific) that causes the same effects e.g. nervous system disruption or hemotoxicity. Either way, proper treatment of snake wounds requires the attention of qualified medical personnel at hospitals.

How to Keep Snakes Away?

Prevention is the best way to reduce snake encounters and by extension, snakebites. It is evident that the factors causing increased snake encounters mentioned above are beyond an individual’s direct control. However, taking small but significant steps can ensure that you will minimise interaction and conflict with these slithering reptiles.

Dr Tan suggested managing tall grassy areas (locally known as “semak samun”) in your neighbourhood, mowing your grass often and keeping trees and shrubs well-trimmed around your home to ensure that snakes have less places to hide.

Another suggestion is to remove the food supply of snakes. This include rodents and birds, as well as your pets such as cats and small dogs. The destruction of the snakes’ natural habitat forces it to find food in the vicinity and this might include your home.

Dr Tan also suggested clearing up storerooms, kitchens, and woodpiles to reduce potential hiding spots for snakes. For homeowners with gardens, Dr Tan suggests planning your gorgeous landscape to minimise hiding places for snakes. This includes replacing big rocks with smaller river stones or gravel, trimming trees and shrubs as well as removing garden debris frequently. Dr Tan also suggested omitting water feature such as fountains and ponds if your home is prone to snake encounters, as these reptiles love water for its cooling effect and as a source of hydration.

Another suggestion by Dr Tan is to promptly seal cracks and eliminate gaps at home, as well as investing in fences that have smaller mesh or solid sheeting, are well-buried in the ground, and have outward bends on the top to maximise protection against snakes from slithering into your home. Additionally, Dr Tan suggests covering drains with drain covers to avoid snakes and rodents (potential snake prey) from coming into your home.

Dr Tan addressed a common “life hack” of using mothballs and sulphur to prevent snakes from coming into homes. He explained that there is a sliver of truth to using sulphur in deterring snakes, attributed to its strong smell; in the long term, Dr Tan explained that sulphur does not really work. Dr Tan encourages observing the steps given above to effectively reduce snake encounters. Once again, he reminded viewers to treat all snakes that come into your home as venomous and dangerous.

Next, Dr Tan presented steps on how to reduce occurrence of snake encounters during outdoor activities such as camping and hiking. He reminded viewers to watch closely where you step; never reach into concealed areas such as under rocks; shake out sleeping bags and clothing before use, especially if they have been left out for some time; and do not attempt to pick up a snake even if it looks dead.

After experiencing a snakebite, Dr Tan advices some to keep calm. If possible, take a picture of the snake; if it was killed, bring it together with you to the emergency room. Try to immobilise the affected area to slow down the spread of the venom. Seek medical attention at the nearest hospital or medical centre and inform them of your unfortunate snakebite.

Dr Tan also cautions against doing several misinformed actions that are made popular via movie and TV: sucking the blood out of the affected area, applying a tourniquet, cutting the wound open, and applying any lotions or ointments are not effective methods to treat snakebites.

Conclusion

• Snakebites are now considered an environmental and occupational health hazards.
• Snakes are ectotherms (organism that regulates its body temperature largely by exchanging heat with its surrounding environment). This makes it very sensitive to changes to its surroundings; the impact of climate change and anthropogenic activities affects snake ecology and distribution, making snakebite occurrences more commonplace nowadays.
• Interaction and conflict with snakes can be minimised or prevented with the proper knowledge, awareness, and practice.
• Scientifically proven treatments are the right way to manage snakebites.