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Sistrurus miliarius
General Details, Taxonomy and Biology, Venom, Clinical Effects, Treatment, First Aid , Antivenoms
Family: Viperidae
Subfamily: Crotalinae
Genus: Sistrurus
Species: miliarius
Subspecies: miliarius
Common Names
( subsp. miliarius ) Carolina Pygmy Rattlesnake
Region
North America
Countries
United States of America
 
Taxonomy and Biology
Adult Length: 0.40 m
General Shape
Small in length, tapered and cylindrical bodied snake with a moderately long and slender tail terminating in a tiny, segmented rattle. Can grow to a maximum of about 0.60 metres. Head is broad and distinct from narrow neck. Canthus rostralis is sharp. Eyes are small to medium in size with vertically elliptical pupils. Dorsal scales are keeled.
Habitat
Found mainly in swamp, marsh and wooded floodplains, moist grasslands, woodlands and meadows.
Habits
Diurnal and terrestrial snake.
Prey
Feeds mainly on small rodents, frogs, large insects and spiders.
Species Map
Small (Approx 20k) version
 
Venom
Average Venom Qty
20 to 30 mg ( dry weight ), Minton (1974) ( Ref : R000504 ).
General: Venom Neurotoxins
Not present
General: Venom Myotoxins
Unknown
General: Venom Procoagulants
Present but not defined
General: Venom Anticoagulants
Unknown
General: Venom Haemorrhagins
Present but not defined
General: Venom Nephrotoxins
Unknown
General: Venom Cardiotoxins
Not present
General: Venom Necrotoxins
Unknown
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
Mild envenoming only, not likely to prove lethal
General: Rate of Envenoming: Unknown but likely to be low
General: Untreated Lethality Rate: Unlikely to prove lethal
General: Local Effects
Local pain, swelling, bruising & blistering
General: Local Necrosis
Potentially may occur
General: General Systemic Effects
General systemic effects unlikely
General: Neurotoxic Paralysis
Does not occur, based on current clinical evidence
General: Myotoxicity
Does not occur, based on current clinical evidence
General: Coagulopathy & Haemorrhages
Some evidence of coagulopathy (not serious);some bleeding due to haemorrhagins.
General: Renal Damage
Unlikely to occur
General: Cardiotoxicity
Unlikely to occur
General: Other
Shock due to fluid shifts is possible in small children.
 
First Aid
Description: First aid for bites by Viperid snakes likely to cause significant local injury at the bite site (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. 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
Treatment Summary
Bites may cause mild to moderate, rarely severe local effects, non-specific general effects. Admit & observe all cases. Only more severe cases require antivenom. Good wound care important; avoid fasciotomies unless absolutely indicated. Look for shock secondary to fluid shifts into bitten limb & manage appropriately.
Key Diagnostic Features
Local pain, swelling, blistering, rarely necrosis
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: SAmPRO01
Antivenom Name: Polyvalent crotalid antivenom ( CroFab ), Ovine, Fab
Manufacturer: Protherics Inc. (US)
Phone: ++1-615-327-1027
Address: 5214 Maryland Way
Suite 405
Brentwood
Tennessee 37027
USA
Country: U.S.A.
2. 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
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