Snakes Bites

Snake bites that result in serious implications are a relatively uncommon phenomenom in Peninsular Malaysia today, but are possibly still widespread in Borneo. This can be attributed to rapid urban development (and local awareness) that has decreased the frequency of encounters between people and snakes. Borneo, with a much lower urbanisation rate - and many rural settlements - may have a higher incidence of snake bites than the Peninsular. Medically, the common term of poisonous snakes should be more correctly referred to as 'venomous', since venom is injected (ie through snake fangs or a bee sting), while poison is ingested.

It is important to differentiate between snake bites that result in significant envenomations or little to neglible effects, as an overwhelming majority of such cases results from a non-venomous (or mildly venomous) species. As the common person is unable to distinguish between local species, coupled with the widespread fear of snakes ingrained in local culture, a chance encounter often results in death for the slithery creature, while a bite from a harmless snake can result in a frenzied trip to the hospital. The highest risk groups are Orang Asli (Aborigines, who mostly live in the forest) and those involved with high occupational hazards, such as agricultural workers (rubber estates, palm oil plantations and paddy fields that fringe jungles), fishermen (or random diver, from sea snakes) and those involved in some manner with snakes as trade (charmers, or dealers and smugglers for the exotic meat and pet industry).

Among the indigenous people, a high number of medically significant snake bite cases go unreported, as natives prefer crude traditional treatment, merely visit the local clinic or rely on paracetamol (Panadol) as panacea. A recent trend is the emergence of snakes as novelty pets or public exhibits, resulting in adventurous keepers obtaining dangerously venomous snakes, either local or exotic, resulting in accidental bites that require medical treatment. For example, a bite from a rattlesnake occured in 2011 (unreported in local papers) from a worker during a snake exhibition, resulting in serious coma and antivenin flown from Singapore. Another problem is the lack of experience in treating snake bites among medical practioners, who tend to follow generalised procedures obtained from outdated journals, rather than evaluate each patient on a case-to-case basis for a suitable prognosis. This can lead to serious complications from otherwise moderate cases.

In Peninsular Malaysia, pit-vipers and cobras account for the highest percentage of snake bites requiring hospitalisation. While fatalies from local species are relatively rare, a serious envenomation can still cause long-term morbidity or even crippling deformity. Bites from kraits, coral snakes and sea snakes are very rare, though they may be more common in other parts of Asia or across the continent (geographical considerations, native species and cultural factors determine highly the kinds of envenomation that occur; eg a country with a disportionately high fishermen population may incur many sea snake bites, while the presence of a local viper species that thrives in disturbed habitats would result in more bites at rural human habitations).

• Pit-vipers (Crotalids) of local origin produce a primarily cytotoxic venom, composed of proteases that destruct cells including tissue, lymph nodes, vessels and blood components, resulting in severe pain, blisters, edema (swelling) and bleeding (a result of thrombin-like activity and/or depletion of clotting factors). While initially heavily localised, it can lead to shock, systematic bleeding and hypovolemia (decreased blood plasma), causing death. Further effects may include necrosis and secondary infection (including osteomyelitis, especially if bone has been punctured by fangs) leading to physical deformity and disability. The Malayan pit-viper is of special note as its venom exhibits intense hemorrhage qualities, but is restricted to northern states of Perlis and Kedah.
• Cobras (including King Cobras) produce primarily neurotoxic venom, with secondary cytotoxic and hemorrhagic compounds. This attacks the neuromuscular and cardiovascular system, causing progressive paralysis and respiratory failure. Similar to pit-vipers, cobra bites can also result in local swelling and necrosis, leading to infections and/or physical infirmities.
• Krait and coral snake bites are very rare due to their secretive nature, but their venom is primarily neurotoxic with little local effects. Similar to a cobra but without the local pain and swelling, the bitten person will have difficulty breathing, dizziness, paralysis of muscles and in severe envenomations, lapse into a coma and die from respiratory failure.
• Sea snake (Hydrophidae) venom is primarily myotoxic (attacking muscles), very deadly but also very rare. There is little local pain or swelling, but pain in muscle movement, then paralysis, and eventually renal failure leading to death.

• Stay calm, it could be a harmless snake that just bit you.
• If it's not, you'll feel intense pain at the bitten area, or in the case of kraits and coral snakes, begin to get progressively dizzy a short while later (make sure it's not your imagination).
• Don't panic, you'll do stupid things while the venom works its worst.
• Do not tie anything around your bitten limb, arterial torniquets have proven to be dangerous as they cut off blood flow and prevent the venom from circulation (thereby increasing the local effects). A lightly tied torniquet may be helpful in the case of a severe krait or coral snake bite, but since the average person cannot tell the difference, avoid its use.
• Don't cut into the wound either or suck it, this introduces infection. A suction kit if applied immediately may be helpful. Certainly no traditional remedies or first aid such as ice packs and applying topical medicine on the wound.
• Get to the hospital, or seek the nearest medical assistance if unavailable. You'll know how bad the bite is by the degree of pain, level of dizziness/drowsiness or both. If either symptoms are unbearable, you have a sure sign of severe envenomation.
• Take a picture or bring along the snake if possible. Helps with identification but a good ER doctor will be able to tell just by the local effects and/or systematic symptoms (there are really only four types of envenomations in Malaysia, see section above). However, if you've been bitten by an exotic venomous species (keeping it as a pet, or working in the animal trade for public exhibitions or commerce), then you are simply quite screwed if it's a serious envenomation without proper antivenom available.

• Stay calm, you don't see many snake bites but it could just be a mild or moderate envenomation.
• If it's not, get the patient wheeled in and treated with opiates as the pain will evidently be severe. If the patient is losing consciousness while having difficulty breathing, put him on a ventilator. Note the patient may be hyperventilating because of intense pain, which is completely different from a neurotoxic envenomation.
• Don't panic, you need to think rationally for an approriate prognosis. Many (inexperienced) doctors will follow textbook guidelines without first evaluating the severity of envenomation, identifying the correct species and consider more passive forms of treatment.
• Antivenom can cause complications; use it sparringly. In Malaysia, only the polyvalent serum from India, raised against cobras (Naja sp) and non-local species of; Indian krait (Bungarus caerulus), Russell's pit-viper (Vipera russelli) and saw-scaled viper (Echis carinatus), and monovalent Malayan pit-viper (Calloselasma rhodostoma) serum from Thai Red Cross is available. While the former is effective for local cobras, kraits and possibly coral snakes, the latter should only be used for confirmed, severe Malayan pit-viper envenomations. This species is restricted to Perlis, Kedah and possibly extreme north of Perak and Kelantan, so do not confuse it with local vipers bites that occur at other states (unless the bitten person confirms it; by having kept the specimen as a pet, or worked in the animal trade).
• A heavily-swollen, cold limb with weak pulse does not equate to compartmental syndrome for an overwhelming number of envenomations. True compartment syndrome can only be confirmed by intracompartment pressure measurement, higher than 30-40 mmHg. Unfortunately, most (inexperienced) doctors are only too eager to jump into fasciotomy with disastrous results, causing disfigurement and excessive bleeding.
• Post-discharge bacterial infection (especially from pit-viper bites) is an overlooked area that can lead to long-term or permanent disability, as the layperson is not trained to recognise local or systematic symptoms in the absence of severe pain during home convalescence. Even where necrosis is not present at discharge, envenomation cases with significant local/systematic effects should be followed up (also to check for functional problems or serum sickness if antivenin was applied) and the patient told to return to hospital as the first signs of fever, redness, tenderness and prolonged swelling at the bitten area. If left unmonitored, secondary infections such as osteomyelitis can occur, leading to long-term or permanent disability.
• Your patient is not your guinea pig, consult colleagues with significant expertise in this area. Few doctors have ever seen snake bite cases of a severe nature. If you are not confident in treatment, don't be too stubborn to refer your case to an experienced doctor or transfer the patient to another hospital. After all, your patient's life, and long-term well-being, lies at stake.

Data on regional snake bite management in Malaysia today is insufficient, most studies being outdated or highly localised. Despite the Malayan pit-viper being restricted to the northern states, hospitals across the Peninsular continue to stock its monovalent antivenom serum, which is expensive while being unsuitable for other species of viper bites. Instead, the polyvalent Trimeresurus antivenom serum from National Institute of Preventive Medicine, Taiwan, should be imported, having shown in studies to be cross-reactive with several local species, since many native vipers also belong to the Asian pit-viper Trimeresurus complex. While most viper bites occur in the northern states (due to the geographical range of the Malayan pit-viper), bites by other lesser-known species do occur elsewhere, especially among Aborigines (Orang Asli), agricultural workers, and those living in rural communities fringing jungles, making them medically significant.

While often looked down as having weaker venom, local viper species (beyond the Malayan pit-viper) have been unofficially documented in some cases to cause severe envenomations, resulting in morbidity, deformity and even death. Hence, the toxicity of such viper species may be more dangerous than known - with specific antivenin treatment being unavailable. Also, a significant percentage of unidentified snake bites requiring hospital admission presumably involve such species, but as doctors are not ecologists, lump every viper bite they see under Calloselasma rhodostoma (even when geographically impossible, considering their highly restricted northern range), consequently squandering monovalent serum. On the other hand, the current polyvalent solution for elapids is suitable for addressing the neurotoxic effects of localcobras, kraits and presumably coral snakes, along with the use of a ventilator.