Sunday, March 5, 2017

Cambodia - Very Venomous Snakes Found - Trimeresurus vogeli

Trimeresurus vogeli

Family: Viperidae

Subfamily: Crotalinae

Genus: Trimeresurus

Species: vogeli

Common Names: Vogel's Green Pitviper , Vogel's Pitviper

Region: Southeast Asia

Countries: Cambodia, Laos, Thailand, Vietnam

Trimeresurus vogeli

Taxonomy and Biology

Adult Length: 0.60 m

General Shape: Medium in length, slightly laterally compressed and moderately elongate, moderately slender ( males ) to medium ( females ) bodied snake with a moderately short ( relatively long in males for genus ) gradually tapering prehensile tail. Can grow to a maximum of at least 1.30 metres ( few recorded specimens ). Head is large, thick, subtriangular shaped with a distinct canthus rostralis and clearly distinct from neck. Snout is somewhat elongate, flattened, rounded when viewed from above and truncated when viewed laterally. Eyes are yellowish or yellowish green, moderately small in size with vertically elliptical pupils. Dorsal scales are moderate to strongly keeled ( smooth on the 1st scale row ). Dorsal scale count ( 25 to 27 ) - 21 - 15.

Habitat: Tropical moist evergreen forest and tropical moist montane forest.

Habits: Arboreal and mainly nocturnal snake.

Prey: Feeds mainly on mice, lizards and birds.

Trimeresurus vogeli


General: Venom Neurotoxins
Probably not present
General: Venom Myotoxins
Probably not present
General: Venom Procoagulants
Possibly present
General: Venom Anticoagulants
Possibly present
General: Venom Haemorrhagins
Possibly present
General: Venom Nephrotoxins
General: Venom Cardiotoxins
Probably not present
General: Venom Necrotoxins
General: Venom Other

Clinical Effects

General: Dangerousness
Unknown, but potentially lethal envenoming cannot be excluded.
General: Rate of Envenoming
Unknown but likely to be high
General: Untreated Lethality Rate
Unknown but lethal potential cannot be excluded
General: Local Effects
Unknown; related species can cause marked local effects; pain, severe swelling, bruising, blistering, necrosis
General: Local Necrosis
Potentially may occur
General: General Systemic Effects
Insufficient clinical reports to know
General: Neurotoxic Paralysis
Unlikely to occur
General: Myotoxicity
Not likely to occur
General: Coagulopathy & Haemorrhages
Unknown, but related species uncommonly to rarely can cause moderate to severe coagulopathy
General: Renal Damage
No case reports for this species, but related species can cause renal failure
General: Cardiotoxicity
Unlikely to occur
General: Other
Shock secondary to fluid shifts due to local tissue injury is likely in severe cases

First Aid


First aid for bites by Viperid snakes likely to cause significant local injury at the bite site.


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.


Treatment Summary: New species, effects unknown, possibly similar to T. stejnegeri: Bites by which cause moderate, possibly major local & systemic effects, including coagulopathy/bleeding. Urgently assess & admit all cases. Antivenom therapy is probably the key treatment, especially for coagulopathy.

Key Diagnostic Features: Local pain, swelling, blistering, necrosis + coagulopathy, bleeding

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.

Antivenom Therapy: Only antivenoms available are for related species, but should be used for significant envenoming.


1. Antivenom Code: SAsTRC01
Antivenom Name: Green Pit Viper Antivenin
Manufacturer: Science Division, Thai Red Cross Society
Phone: ++66-2-252-0161 (up to 0164)
Address: Queen Saovabha Memorial Institute
1871 Rama IV Road
Bangkok 10330

Country: Thailand

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