- Malabar pit viper bites are widely considered insignificant, but emerging evidence shows they can cause severe local effects, coagulopathy and renal dysfunction.
- Current antivenoms show poor neutralisation against pit viper venoms, strengthening the case for species-specific or broader polyvalent antivenoms.
- Identification gaps, camouflage and nocturnal bite circumstances contribute to under-reporting and limited understanding of Malabar pit viper envenoming.
What do we know about Malabar pit vipers? Surprisingly little, despite it being a striking, enigmatic reptile endemic to the Western Ghats. The Malabar pit viper (Craspedocephalus malabaricus) is known for its remarkable colour polymorphism; it appears in rare and vivid shades — from almond brown and mustard yellow to sage green, coral and many more. Few snakes possess such dramatic variation, making this species one of the Western Ghats’ most aesthetically gifted inhabitants. However, despite it being a medically significant species, there is very little information about Malabar pit viper envenoming as its bites are widely considered insignificant.
A team of scientists have published a paper examining various aspects of how venom is passed on through the snake’s bites in a bid to bridge knowledge gaps and inform clinical management. “One of the reasons why envenoming from pit vipers like these (Malabar pit viper) is not well known, and the reason why we are working on them, is that there are big gaps in snake identification when bites occur,” explains Freston Marc Sirur, associate professor, Centre for Wilderness Medicine at Kasturba Medical College in Manipal, Karnataka, who led the study. “In certain circumstances, the patient has not seen the snake. Sometimes the bite happens at night. Sometimes it’s in grass or shrubs and the snake is not visible,” he elaborates.
Malabar pit vipers are arboreal and are masters of camouflage. In many cases, Sirur says, bites happen from the branches of a tree or while the survivors are working in the bushes. “Interestingly, we’ve had cases of people being bitten on the face or the upper body,” he says.
The researchers studied 16 confirmed and presumed Malabar pit viper envenoming cases reported at a tertiary care centre in coastal Karnataka between May 2018-March 2024. They found that all 16 patients had severe local envenoming (i.e. marked local effects at the bite site). Additionally, 50% developed coagulopathy (blood-clotting dysfunction), and 25% showed mild renal (kidney) dysfunction. Some cases required interventions for local complications, including compartment syndrome, a serious condition where increased pressure within a muscle compartment cuts off blood flow, leading to oxygen deprivation, pain, and potential nerve/muscle damage.
Sirur says that the evidence is enough to support the need for a species-specific antivenom. He says, “We are raising awareness about these lesser-known but medically significant venomous snakes so that antivenom manufacturers can consider adding them to their immunisation pools — either as part of a broader polyvalent antivenom, or as monovalent antivenoms if that makes sense to policymakers.”
Medical importance of pit vipers
A 2023 study on the medical importance of pit vipers in the Western Ghats also evaluated the venom composition, biochemical activities, toxicity and morbidity potential of three pit viper species — hump-nosed viper (Hypnale hypnale), Malabar pit viper (Craspedocephalus malabaricus), and bamboo pit viper (Craspedocephalus gramineus). The study found that although the “big four” snakes — Russell’s viper (Daboia russelii), Common krait (Bungarus caeruleus), Indian cobra (Naja naja) and Indian saw-scaled viper (Echis carinatus) — are the main focus in India, these pit vipers contribute significantly to snakebite morbidity, sometimes exceeding the big four in bite frequency in specific regions.
The paper highlights that Malabar pit viper could induce severe hemorrhagic and necrotic effects with potential for serious tissue damage. Moreover, the study documents that all three pit viper venoms cause significant nephrotoxicity, making a case for specific antivenom against pit viper envenoming in India.
Scientist and professor Kartik Sunagar at the Centre for Ecological Sciences, who led the study, informs Mongabay-India that the study highlighted that Malabar pit viper, and even bamboo pit viper, have potent venom. However, they produce so little that the bites are rarely severe. “Both Malabar pit viper, and bamboo pit viper have venom potency almost on a par with the hump-nosed pit viper in many cases. In fact, we saw a lot more coagulopathy with Malabar pit viper compared to hump-nosed, but the thing is they produce very little venom which makes the bites not very significant in most cases.” He, however, affirms that the available anti-venom doesn’t really neutralise the venom very well.
Through the latest study, Sirur and team aim to raise awareness about the potency of Malabar pit viper envenoming. “More research and more awareness are needed — among both medical communities and the public. Many people still live with complications or seek non-medical care initially, which delays emergency treatment.” Until that happens, researchers warn that any snakebite needs immediate medical intervention. “You are not fully aware of a person’s underlying conditions and you don’t know how the venom will act. It’s always best to go to the hospital without delay,” Sunagar says.
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Banner image: Given that existing anti-venom does not neutralise the venom of a Malabar pit viper, the study authors are raising awareness about these lesser known but medically significant venomous snakes so that antivenom manufacturers can consider adding them to their immunisation pools. Image by Bose Madappa.
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