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Family: Viperidae
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Subfamily: Crotalinae
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Genus: Calloselasma
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Species: rhodostoma
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Common Names
Malayan Pit Viper
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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.
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Region
Southeast Asia
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Countries
Cambodia, Indonesia, Laos, Malaysia, Myanmar, Thailand, Vietnam
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Taxonomy and Biology
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Adult Length: 0.50 m
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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 ).
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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.
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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.
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Prey
Feeds mainly on rodents, lizards and frogs and occasionally birds. Young feed on insects and small lizards.
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Venom
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Average Venom Qty
40 to 60 mg ( dry weight ), Minton (1974) ( Ref : R000504 ).
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General: Venom Neurotoxins
Not present
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General: Venom Myotoxins
Not present
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General: Venom Procoagulants
Fibrinogenases
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General: Venom Anticoagulants
Not present
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General: Venom Haemorrhagins
Present but not defined
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General: Venom Nephrotoxins
Not present
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General: Venom Cardiotoxins
Not present
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General: Venom Necrotoxins
Secondary necrotoxic activity only
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General: Venom Other
Not present or not significant
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Clinical Effects
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General: Dangerousness
Severe envenoming possible, potentially lethal
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General: Rate of Envenoming: 60-80%
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General: Untreated Lethality Rate: 1-10%
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General: Local Effects
Marked local effects; pain, severe swelling, bruising, blistering
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General: Local Necrosis
Common, moderate to severe
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General: General Systemic Effects
Variable non-specific effects which may include headache, nausea, vomiting, abdominal pain, diarrhoea, dizziness, collapse or convulsions
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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
Common, moderate to severe coagulopathy + haemorrhagins causing extensive bleeding
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General: Renal Damage
Uncommon to rare, usually secondary effect
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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 likely 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
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).
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Key Diagnostic Features
Local pain, swelling, blistering, necrosis + coagulopathy, bleeding, renal failure
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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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1. Antivenom Code: SAsTRC06
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Antivenom Name: Malayan Pit Viper Antivenin
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Manufacturer: Science Division, Thai Red Cross Society
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Phone: ++66-2-252-0161 (up to 0164)
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Address: Queen Saovabha Memorial Institute 1871 Rama IV Road Pathumwan Bangkok 10330
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Country: Thailand
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2. Antivenom Code: SAsPBF01
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Antivenom Name: Antivenin Polyvalent (Equine)
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Manufacturer: P.T. Bio Farma ( Persero )
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Phone: ++62-22-203-3755
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Address: Jl. Pasteur 28 Bandung 40161
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Country: Indonesia
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3. Antivenom Code: SAsGPO01
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Antivenom Name: Malayan Pit Viper Antivenom
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Manufacturer: Thai Government Pharmaceutical Organisation
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Phone: ++662-644-8851
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Address: 75/1 Rama VI Road, Ratchathewi Bangkok 10400,
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Country: Thailand
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4. Antivenom Code: SAsVRU01
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Antivenom Name: Calloselasma rhodostoma - Malayan Pit Viper Antivenom
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Manufacturer: Venom Research Unit
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Address: University of Medicine and Pharmacy Ho Chi Minh City 217 An Duong Vuong Q5
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Country: Vietnam
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5. Antivenom Code: SAsVRU02
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Antivenom Name: Calloselasma rhodostoma - Malayan Pit Viper Antivenom
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Manufacturer: Venom Research Unit
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Address: University of Medicine and Pharmacy Ho Chi Minh City 217 An Duong Vuong Q5
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Country: Vietnam
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