Saturday, March 4, 2017

Cambodia - Very Venomous Snakes Found - Calloselasma rhodostoma

Calloselasma rhodostoma ( Malayan Pit Viper )
Original photo copyright © Dr Anita Malhotra

Family: Viperidae

Subfamily: Crotalinae

Genus: Calloselasma

Species: rhodostoma

Common Names: Malayan Pit Viper

Local Names: Ulah Kapak Bodoh , Ularkapak Daun , Ular Tanah , Ular Biludak , Ular Gebuk , Ular Bandotan Bedor , Ngu Kapa , Ngu Kaba , Ngu Maaw-sao , Oraj Lemah.

Region: Southeast Asia

Countries: Cambodia, Indonesia, Laos, Malaysia, Myanmar, Thailand, Vietnam

Calloselasma rhodostoma ( Malayan Pit Viper ) Original photo copyright © Dr Julian White

Taxonomy and Biology

Adult Length: 0.50 m

General Shape: Small to medium in length, stout, flattened, but thick bodied snake, with a very short and narrow tail distinct from the body. Can grow to a maximum of about 1.10 metres. Head is large, broad, flattened, triangular shaped with a bluntly pointed and slightly upturned snout and very distinct from neck. Canthus rostralis is distinct. Head dorsum shields are large. Eyes are medium in size with vertically elliptical pupils. Dorsal scales are smooth with apical pits. Dorsal scale count 23 ( 19 - 25 ) - 21 ( 19 ) - 17 ( 15 to 19 ).

Habitat: Elevations up to about 2000 metres but most common in lowland forest, hillside slopes and cultivated regions. Particularly common in dry secondary growth habitats, in rubber plantations and near rice paddy fields.

Habits: Terrestrial and mainly nocturnal, but also active during the day on occasions. Often found crossing roads at night. Tends to be most active at times of high humidity. Tends to remain motionless to avoid detection. Not an aggressive snake but will strike readily if disturbed.

Prey: Feeds mainly on rodents, lizards and frogs and occasionally birds. Young feed on insects and small lizards.

Calloselasma rhodostoma ( Malayan Pit Viper ) Original photo copyright © Dr Wolfgang Wuster


General: Venom Neurotoxins
Not present
General: Venom Myotoxins
Not present
General: Venom Procoagulants
General: Venom Anticoagulants
Not present
General: Venom Haemorrhagins
Present but not defined
General: Venom Nephrotoxins
Not present
General: Venom Cardiotoxins
Not present
General: Venom Necrotoxins
Secondary necrotoxic activity only
General: Venom Other
Not present or not significant

Calloselasma rhodostoma ( Malayan Pit Viper ) Original photo copyright © Dr Wolfgang Wuster

Clinical Effects

General: Dangerousness
Severe envenoming possible, potentially lethal
General: Rate of Envenoming
General: Untreated Lethality Rate
General: Local Effects
Marked local effects; pain, severe swelling, bruising, blistering
General: Local Necrosis
Common, moderate to severe
General: General Systemic Effects
Variable non-specific effects which may include headache, nausea, vomiting, abdominal pain, diarrhoea, dizziness, collapse or convulsions
General: Neurotoxic Paralysis
Unlikely to occur
General: Myotoxicity
Not likely to occur
General: Coagulopathy & Haemorrhages
Common, moderate to severe coagulopathy + haemorrhagins causing extensive bleeding
General: Renal Damage
Uncommon to rare, usually secondary effect
General: Cardiotoxicity
Unlikely to occur
General: Other
Shock secondary to fluid shifts due to local tissue injury is likely in severe cases

Calloselasma rhodostoma ( Malayan Pit Viper ) Original photo copyright © Franck Principaud

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.

Calloselasma rhodostoma ( Malayan Pit Viper ) Original photo copyright © Franck Principaud


Treatment Summary: Malayan pit viper bites can cause severe local & systemic effects, potentially lethal, so require urgent assessment & treatment with IV fluids, good wound care, avoid early surgical intervention, early IV antivenom therapy (only effective treatment for severe coagulopathy/bleeding).

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

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: Antivenom is the key treatment for systemic envenoming. Multiple doses may be required.


1. Antivenom Code: SAsTRC06
Antivenom Name: Malayan 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

2. Antivenom Code: SAsPBF01
Antivenom Name: Antivenin Polyvalent (Equine)
Manufacturer: P.T. Bio Farma ( Persero )
Phone: ++62-22-203-3755
Address: Jl. Pasteur 28
Bandung 40161
Country: Indonesia

3. Antivenom Code: SAsGPO01
Antivenom Name: Malayan Pit Viper Antivenom
Manufacturer: Thai Government Pharmaceutical Organisation
Phone: ++662-644-8851
Address: 75/1 Rama VI Road,
Bangkok 10400,
Country: Thailand

4. Antivenom Code: SAsVRU01
Antivenom Name: Calloselasma rhodostoma - Malayan Pit Viper Antivenom
Manufacturer: Venom Research Unit
Address: University of Medicine and Pharmacy
Ho Chi Minh City
217 An Duong Vuong Q5
Country: Vietnam

5. Antivenom Code: SAsVRU02
Antivenom Name: Calloselasma rhodostoma - Malayan Pit Viper Antivenom
Manufacturer: Venom Research Unit
Address: University of Medicine and Pharmacy
Ho Chi Minh City
217 An Duong Vuong Q5

Country: Vietnam

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