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![Trimeresurus trigonocephalus ( Sri Lankan Green Pit Viper ) [ Original photo copyright © Dr Anita Malhotra ]](images/snakes/SNP01221.jpg)
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Family: Viperidae
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Subfamily: Crotalinae
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Genus: Trimeresurus
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Species: trigonocephalus
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Common Names
Sri Lankan Green Pit Viper , Ceylon Green Pit Viper
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Local Names
Pala Polonga , Pachi Viriyan
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Region
Indian Sub-continent
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Countries
Sri Lanka
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Taxonomy and Biology
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Adult Length: 0.70 m
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General Shape
Medium in length, cylindrical, medium to moderately robust bodied snake with a short prehensile tail. Can grow to a maximum of about 1.30 metres. Head is large, triangular shaped and distinct from neck. Eyes are medium in size with vertically elliptical pupils. Dorsal scales are strongly imbricate, smooth or very faintly keeled. Posterior ventral usually notched or divided in two. Dorsal scale count ( 17 or 19 ) - ( 17 or 19 ) - ( 13 or 15 ).
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Habitat
Found in primary and secondary forest ( up to about 1800 metres ) in trees ranging from small shrubs and weed grasses to high up in tall trees. Most common in the wet zone rain forests near streams and encountered in plantations, particularly cocoa, coffee and tea. Appears to adapt to any micro habitat within its range.
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Habits
Nocturnal, sluggish and arboreal, but will often descend to ground level in search of prey and water. Rarely found near human habitation. Although sluggish, it can strike with speed. If threatened it will raise and retract its forebody ready to strike. It rarely hisses.
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Prey
Feeds mainly on frogs, geckos, rodents and birds.
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Venom
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General: Venom Neurotoxins
Probably not present
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General: Venom Myotoxins
Unknown
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General: Venom Procoagulants
Unknown
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General: Venom Anticoagulants
Unknown
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General: Venom Haemorrhagins
Unknown
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General: Venom Nephrotoxins
Unknown
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General: Venom Cardiotoxins
Probably not present
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General: Venom Necrotoxins
Unknown
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General: Venom Other
Unknown
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Clinical Effects
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General: Dangerousness
Unknown, but potentially lethal envenoming, though unlikely, cannot be excluded.
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General: Rate of Envenoming: Unknown but likely to be moderate
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General: Untreated Lethality Rate: Unknown but lethal potential cannot be excluded
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General: Local Effects
Insufficient clinical reports to know, but possibly marked local effects; pain, severe swelling, bruising, blistering, but not necrosis
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General: Local Necrosis
Does not occur, based on current clinical evidence
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General: General Systemic Effects
Does not occur, based on current clinical evidence
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General: Neurotoxic Paralysis
Unlikely to occur
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General: Myotoxicity
Not likely to occur
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General: Coagulopathy & Haemorrhages
No reports of coagulopathy, though related species can cause bleeding problems
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General: Renal Damage
Insufficient clinical reports to know
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General: Cardiotoxicity
Unlikely to occur
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General: Other
Shock secondary to fluid shifts due to local tissue injury is possible in severe cases
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First Aid
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Description: First aid for bites by Viperid snakes likely to cause significant local injury at the bite site (see listing in Comments section).
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Details
1. After ensuring the patient and onlookers have moved out of range of further strikes by the snake, the bitten person should be reassured and persuaded to lie down and remain still. Many will be terrified, fearing sudden death and, in this mood, they may behave irrationally or even hysterically. The basis for reassurance is the fact that many venomous bites do not result in envenoming, the relatively slow progression to severe envenoming (hours following elapid bites, days following viper bites) and the effectiveness of modern medical treatment.
2. The bite wound should not be tampered with in any way. Wiping it once with a damp cloth to remove surface venom is unlikely to do much harm (or good) but the wound must not be massaged.
3. All rings or other jewellery on the bitten limb, especially on fingers, should be removed, as they may act as tourniquets if oedema develops.
4. The bitten limb should be immobilised as effectively as possible using an extemporised splint or sling; if available, crepe bandaging of the splinted limb is an effective form of immobilisation.
5. If there is any impairment of vital functions, such as problems with respiration, airway, circulation, heart function, these must be supported as a priority. In particular, for bites causing flaccid paralysis, including respiratory paralysis, both airway and respiration may be impaired, requiring urgent and prolonged treatment, which may include the mouth to mask (mouth to mouth) technique of expired air transfer. Seek urgent medical attention.
6. Do not use Tourniquets, cut, suck or scarify the wound or apply chemicals or electric shock.
7. Avoid peroral intake, absolutely no alcohol. No sedatives outside hospital. If there will be considerable delay before reaching medical aid, measured in several hours to days, then give clear fluids by mouth to prevent dehydration.
8. If the offending snake has been killed it should be brought with the patient for identification (only relevant in areas where there are more than one naturally occurring venomous snake species), but be careful to avoid touching the head, as even a dead snake can envenom. No attempt should be made to pursue the snake into the undergrowth as this will risk further bites.
9. The snakebite victim should be transported as quickly and as passively as possible to the nearest place where they can be seen by a medically-trained person (health station, dispensary, clinic or hospital). The bitten limb must not be exercised as muscular contraction will promote systemic absorption of venom. If no motor vehicle or boat is available, the patient can be carried on a stretcher or hurdle, on the pillion or crossbar of a bicycle or on someone's back.
10. Most traditional, and many of the more recently fashionable, first aid measures are useless and potentially dangerous. These include local cauterization, incision, excision, amputation, suction by mouth, vacuum pump or syringe, combined incision and suction ("venom-ex" apparatus), injection or instillation of compounds such as potassium permanganate, phenol (carbolic soap) and trypsin, application of electric shocks or ice (cryotherapy), use of traditional herbal, folk and other remedies including the ingestion of emetic plant products and parts of the snake, multiple incisions, tattooing and so on.
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Treatment
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Treatment Summary
Bites by this species cause moderate, possibly major local effects. Assess & admit all major cases. Antivenom therapy is probably the key treatment.
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Key Diagnostic Features
Local pain, swelling, blistering, necrosis + coagulopathy, bleeding
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General Approach to Management
All cases should be treated as urgent & potentially lethal. Rapid assessment & commencement of treatment including appropriate antivenom (if indicated & available) is mandatory. Admit all cases.
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Antivenom Therapy
Antivenom is the key treatment for systemic envenoming. Multiple doses may be required.
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