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Crotalus durissus
General Details, Taxonomy and Biology, Venom, Clinical Effects, Treatment, First Aid , Antivenoms
Crotalus durissus ( Neotropical Rattlesnake ) subsp. terrificus  [ Original photo copyright © Dr Wolfgang Wuster ]
Family: Viperidae
Subfamily: Crotalinae
Genus: Crotalus
Species: durissus
Subspecies: terrificus (Note that this taxon is without uniform recognition by taxonomists)
Common Names
( subsp. terrificus ) Neotropical Rattlesnake , Cascabel , South American Rattlesnake
Local Names
Boicininga , Boicinunga , Boicuninga , Boicununga , Cascabel , Cascabela , Cascavel , Cascavel de Cuatro Ventas , Chonono , Cobra de Guizo , Maraca , Maraca-boia , Mboi chi-ni , Serpiente de Cascabel , Vibora Cascabel , Vibora de Cascabel
Region
South America
Countries
Argentina, Bolivia, Brazil, Paraguay, Peru, Uruguay
 
Taxonomy and Biology
Adult Length: 0.95 m
General Shape
Medium to large in length, stout bodied rattlesnake with a short tail and a horn-like segmented rattle. Can grow to a maximum of about 1.60 metres. Head is large, broad and very distinct from narrow neck. Eyes are medium to moderately small in size with vertically elliptical pupils. Spinal ridge is evident, particularly anteriorly, and dorsal scales are strongly keeled and tuberculate.
Habitat
Elevations up to about 1000 metres in mainly chaco, pampas grassland and wet palm grassland; also dry caatinga, cerrado and dry forest.
Habits
Terrestrial and diurnal snake.
Prey
Feeds mainly on lizards, rodents, small mammals and birds.
Species Map
Small (Approx 20k) version
 
Venom
Average Venom Qty
25 to 40 mg ( dry weight ), Minton (1974) ( Ref : R000504 ).

Goias, Brazil : 76 mg ( dry weight ) ( range 28 to 127 ), Sao Paulo, Brazil : 50 mg ( dry weight ) ( range 28 to 67 ), Sanchez et al (1992) ( Ref : R000690 ).

Argentina : 140.4 ± 21 mg ( dry weight ) = 7.39 ± 1.13 mg venom / 100 g body weight, De Roodt et al (1988) ( Ref : R000870 ).
General: Venom Neurotoxins
Presynaptic neurotoxins
General: Venom Myotoxins
Secondary myotoxicity present
General: Venom Procoagulants
Fibrinogenases
General: Venom Anticoagulants
Not present
General: Venom Haemorrhagins
Not present
General: Venom Nephrotoxins
Secondary nephrotoxicity only
General: Venom Cardiotoxins
Not present
General: Venom Necrotoxins
Not present
General: Venom Other
May include; Lectins; Nerve growth factors; Phospholipase inhibitors; Proteinase inhibitors; Complement inactivators; Biogenic amines; Carbohydrates; Lipids; Nucleosides & nucleotides
 
Clinical Effects
General: Dangerousness
Severe envenoming possible, potentially lethal
General: Rate of Envenoming: 40-60%
General: Untreated Lethality Rate: 30-40%
General: Local Effects
None or minimal
General: Local Necrosis
Does not occur, based on current clinical evidence
General: General Systemic Effects
Variable non-specific effects which may include headache, nausea, vomiting, abdominal pain, diarrhoea, tachypnoea, respiratory distress, hypotension, dizziness, collapse or convulsions
General: Neurotoxic Paralysis
Very common, flaccid paralysis is major clinical effect
General: Myotoxicity
Very common, major clinical effect, usually moderate to severe
General: Coagulopathy & Haemorrhages
Moderate coagulopathy, even defibrination can occur in at least some cases
General: Renal Damage
Recognised complication, usually secondary to myolysis
General: Cardiotoxicity
Can cause hyperkalaemic cardiotoxicity secondary to myolysis.
General: Other
Does not occur, based on current clinical evidence
 
First Aid
Description: First aid for bites by Viperid snakes not likely to cause significant injury at the bite site or where general (systemic) effects are likely to be more important than local effects (see listing in Comments section).
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. If the bite is on a limb, a broad bandage (even torn strips of clothing or pantyhose) should be applied over the bitten area at moderate pressure (as for a sprain; not so tight circulation is impaired), then extended to cover as much of the bitten limb as possible, including fingers or toes, going over the top of clothing rather than risking excessive limb movement by removing clothing. The bitten limb should then be immobilised as effectively as possible using an extemporised splint or sling.
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. In Australia and parts of New Guinea, Snake Venom Detection Kits are available to identify the snake from venom left on the skin.
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
Treatment Summary
Bites by species showing the South American rattlesnake clinical pattern are quite different from North American rattlesnake bites. The bite may cause few if any local effects, but can cause severe, even lethal systemic effects, particularly paralysis & myolysis (coagulopathy also possible). Therefore every case must be admitted at least overnight and closely observed. Should any evidence of paralysis or myolysis develop, antivenom is the principal treatment. Specific antivenoms exist for several major species.
Key Diagnostic Features
Minimal to mild local reaction + flaccid paralysis, myolysis, sometimes 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
Antivenom is the key treatment for systemic envenoming. Multiple doses may be required.
Antivenoms
1. Antivenom Code: SAmIBB04
Antivenom Name: Soro anticrotalico
Manufacturer: Instituto Butantan
Phone: +55-11-3726-7222
Address: Av. Vital Brasil, 1500 Butanta
05503-900
Sao Paulo - SP
Country: Brazil
2. Antivenom Code: SAmFED02
Antivenom Name: Soro Anti-botropico-crotalico
Manufacturer: Fundacao Ezequiel Dias - FUNED
Phone: ++55-31-3371-9525
Address: Rua Conde Pereira Carneiro, 80 - Gameleria
Belo Horizonte, MG - CEP 30510-010
Country: Brazil
3. Antivenom Code: SAmFED03
Antivenom Name: Soro Anticrotalico
Manufacturer: Fundacao Ezequiel Dias - FUNED
Phone: ++55-31-3371-9525
Address: Rua Conde Pereira Carneiro, 80 - Gameleria
Belo Horizonte, MG - CEP 30510-010
Country: Brazil
4. Antivenom Code: SAmINP03
Antivenom Name: Suero Anticrotalico
Manufacturer: Instituto Nacional de Salud
Phone: ++51-1-467-4499
Address: Centro Nacional de Produccion de Biologicos
Av. Defensores del Morro 2268
Chorrillos
Lima 9
Country: Peru
5. Antivenom Code: SAmNIA03
Antivenom Name: Anticrotalus
Manufacturer: Instituto Nacional de Produccion de Biologics
A.N.L.I.S.
Phone: ++54-11-4303-1806 (to 11)
Address: Avdo. Velez Sarsfield 563,
CP 1281 Buenos Aires,
Country: Argentina
6. Antivenom Code: SAmNIA05
Antivenom Name: Tropical trivalente
Manufacturer: Instituto Nacional de Produccion de Biologics
A.N.L.I.S.
Phone: ++54-11-4303-1806 (to 11)
Address: Avdo. Velez Sarsfield 563,
CP 1281 Buenos Aires,
Country: Argentina
7. Antivenom Code: SAmIBB07
Antivenom Name: Soro antibotropico-crotalico
Manufacturer: Instituto Butantan
Phone: +55-11-3726-7222
Address: Av. Vital Brasil, 1500 Butanta
05503-900
Sao Paulo - SP
Country: Brazil
8. Antivenom Code: SAmIBA01
Antivenom Name: Suero Antifidico Polivalente BIOL (Suero Antiofidoco para mordedura de Yarara, De la Cruz y Cscabel)
Manufacturer: Instituto Biologico Argentino S.A.I.C.
Phone: ++54-11-4953-7215
Address: Jose E. Uriburu 153
C1027 AAC Buenos Aires
Country: Argentina
9. Antivenom Code: SAmIBM06
Antivenom Name: Antivipmyn
Manufacturer: Instituto Bioclon
Phone: ++56-65-41-11
Address: Calzada de Tlalpan No. 4687
Toriello Guerra
C.P. 14050
Mexico, D.F.,
Country: Mexico
Crotalus durissus ( Neotropical Rattlesnake ) subsp. terrificus [ Original photo copyright © Dr Wolfgang Wuster ]
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