Envenomation

When a cone snail envenomates its prey, the latter is invariably paralyzed. In all cases, the paralytic toxins in the venom ("conotoxins") appear to be small peptides, most commonly with 3 disulfide bonds (although conotoxins with 2 or 4 S-S bonds... 

The cone snails constitute one of the largest groups of animals that use venoms as their primary weapon for capturing prey (300—500 species). Furthermore, they have successfully envenomated a much wider variety of prey than has been observed for most venomous animal genera. 

Table I. Important Disorders Produced by Jellyfish Envenomation...

All the jellyfish venoms are toxic but also stimulate the cell mediated and humoral immunological systems of man. After injection of large doses of jellyfish venom into human skin, a perivascular mononuclear cell infiltration appears within the dermis. This infiltration is composed predominantly of helper inducer cells which produce suppressor activity. It appears that the NK enhancement of human leukocytes in patients envenomated by Chrysaora quinquecirrha is depressed when the clinical lesion is inflammatory (10). Recovery from this suppression follows the amelioration of the acute cutaneous reaction. In other instances, envenomated patients have abnormal macrophage migration tests (11). 

Chizar D. Walters A., Urbaniak J., Smith H., et al. (1999). Discrimination between envenomed and non-envenomed prey by W. Diamond-backed rattlesnakes (C. atrox). Copeia 3, 640-648. 

Two phenomena of reptilian prey searching are well investigated responses of various snakes to the odors of invertebrates, and rattlesnakes trailing of envenomated small mammals. 

The rattlesnake C. viridis searches for the particular odor it had experienced when striking the prey. In one experiment, snakes were induced to strike perfume-treated mice. Then they were exposed to perfumed, but non-envenomated, carcasses. The snakes preferred a carcass with the same odor as the originally struck mouse. In a second experiment, snakes preferred the carcasses of mice on the same diet as the ones they had struck. Thus rattlesnakes form a... 

Specific chemical search image (Melcer and Chiszar, 1989). They learn a mouse s chemosensory signature, which is independent of envenomation, and follow its scent trail (Chiszar 1990). 

Chiszar, D., Radcliff, C. W., Scudder, R. M., and Duvall, D. (1983). Strike-induced chemosensory searching by rattlesnakes the role of envenomation-related chemical cues in the post-strike environment. In Chemical Signals in Vertebrates vol. 3, ed. D.Miiller-Schwarze and R. M. Silverstein, pp. 1-24. New York Plenum. 

Smith, T. L. and Kardong, K. V. (2000). Absence of polarity perception by rattlesnakes of envenomated prey trails. Journal of Herpetology 34,621-624. 

Burnett JW Medical aspects of jellyfish envenomation Pathogenesis, case reporting and therapy, Hydrobiologia 451 1—9, 2001. 

In elapid envenomation, the patient complains of pain and numbness at the site of the bite, paralysis of muscles around the bite, lassitude, and drowsiness. These are followed by clouding of consciousness, dimness of vision, breathing difficulty, and cranial nerve paralysis with ptosis, dysarthria, dysphagia and dribbling of saliva. The patient passes into coma, respiration ceases and convulsions appear. In krait bite, symptoms occur later, and cramp-like abdominal pains are common. 

Howarth DM, Southee AE, Whyte IM. Lymphatic flow rates and first-aid in simulated peripheral snake or spider envenomation. Med J Australia 1994 161(11-12) 695-700. 

Offerman SR, Bush SP, Moynihan JA, Clark RF. Cro-taline Fab antivenom for the treatment of children with rattlesnake envenomation. Pediatrics 2002 110(5) 968-71. 

The entire dose should be given within 4 hours after the bite by the IV or IM route (1 vial = 10 mL) upto 15 vials can be used depending upon the degree of envenomation. 

A severe type I hypersensitivity reaction such as systemic anaphylaxis (eg, from insect envenomation, ingestion of certain foods, or drug hypersensitivity) requires immediate medical intervention. 

Snake bite (pit vipers) Antivenin (Crotalidae) polyvalent, equine The entire dose should be given within 4 hours after the bite by the IV or IM route (1 vial = 10 mL) Minimal envenomation 2-4 vials Moderate envenomation 5-9 vials Severe envenomation 10-15 vials Additional doses may be required. Neutralizes the venom of rattlesnakes, copperheads, cottonmouths, water moccasins, and tropical and Asiatic crotalids. Serum sickness occurs in almost all patients who receive > 7 vials. 

Antivenin (Crotalidae) polyvalent immune Fab, ovine An initial dose of 4-6 vials should be infused intravenously over 1 hour. The dose should be repeated if initial control is not achieved. After initial control, 2 vials should be given every 6 hours for up to 3 doses. For the management of minimal to moderate North American crotalid envenomation. 

Features of Envenoming from Bites of Snakes Producing Venoms Containing... 

Presynaptic snake neurotoxins endowed with PLA2 activity (SPANs) are major components of the venom of four families of venomous snakes (Crotalidae, Elapidae, Hydrophiidae, and Viperidae). These neurotoxins play a crucial role in envenomation of the prey (Harris 1997) by causing a persistent blockade of neurotransmitter release from nerve terminals with a peripheral paralysis very similar to that of botulism (Connolly et al. 1995 Gutidrrez et al. 2006 Kularatne 2002 Prasampun et al. 2005 Theakston et al. 1990 Trevett et al. 1995 Warrell et al. 1983). 

There is no accurate estimation of the incidence and number of deaths caused by snake bites in the world. It is possible that tens of thousands of individuals die each year following snake envenomation in Asia, which is the most affected area (Guti6rrez et al. 2006). The death rate has strongly decreased in Australia... 

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