snakebite

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snakebite

 [snāk´bīt]
injury caused by the mouth parts of a snake, usually from venom. It is estimated that the worldwide number of deaths from venomous snakebites may be as high as 50,000 annually, with the greatest number being reported in the Indian subcontinent. In North America most poisonous snakes are pit vipers (rattlesnakes, copperheads, and water moccasins). A few species of coral snakes are found from the southern and southwestern United States southward into Mexico and Central America. Major groups found in other parts of the world include the cobras and the adders.

Not many snakebite deaths occur annually in North America; there are far more deaths from hypersensitivity to insect bites and stings. Practices that increase the incidence of snakebites include failure to wear protective covering for the feet and legs, sleeping outdoors on the ground, and the ritual handling of venomous snakes in some religious ceremonies.
Recognition of Venomous Snakebite. The accurate diagnosis of venomous snakebite is greatly enhanced by capturing or killing the snake and correctly identifying it. Lacking this information, one must depend on clinical manifestations, which can be varied and confusing. One should not depend on visual inspection of the pattern of marks left on the skin. Local swelling may blur the pattern of fang marks; sometimes only one fang of the venomous snake has entered the skin. Nonvenomous snakebites usually do not produce much local swelling or pain, and they bleed freely. These symptoms may, however, also occur in some types of venomous snakebites.
Symptoms. In general, venomous snakebites of the type found in the United States produce severe local pain, swelling that spreads from the site of puncture, and involvement of the lymph glands. The patient may experience nausea and vomiting, thirst, sweating, and a low grade fever. If no other symptoms develop, the prognosis is excellent. More serious symptoms indicating poisoning by a neurotoxin include numbness and tingling of the face, hypotension, convulsions, and visual disturbances. If the snake is the type whose venom contains a hemotoxin, the bite may produce hemorrhaging with hemoptysis, hematuria, and increased prothrombin time.
Treatment. There are conflicting opinions among experts as to the value of incisions over the fang marks and suctioning of venom from the wound if this is done outside a medical facility or by someone other than a specially trained health care provider. Some continue to recommend emergency treatment consisting of immediate application of a tourniquet, deep incisions over the fang marks, and suctioning. Others feel that the application of a tourniquet to reduce peripheral circulation and packing the affected part in ice to reduce absorption of the venom is the best first aid treatment. Some, however, do not recommend use of ice. In any case, the victim is kept calm and as physically inactive as possible and is quickly transported to a medical facility where adequate débridement of the wound and mechanical removal and neutralization of the venom can be done. This also minimizes the danger of introducing infectious agents into the wound.



In addition to local wound treatment, which may require skin grafting at a later date, treatment is concerned with administration of an immune serum (antiserum or antivenin), counteraction of the specific pharmacologic effects of the venom, symptomatic relief, and prevention of complications.
Prevention of Snakebite. Most snakebites are inflicted on people who handle snakes or are foolishly careless in areas where there are known to be venomous snakes. Certain common-sense precautions should be taken when visiting such an area. Important facts to keep in mind are that most snakes are active in the early evening, that they often congregate on rocky slopes facing south or west in order to bask in the sunlight (especially in the spring and fall), and that they are not active at temperatures below 10°C (50°F).

snakebite

(snāk′bīt′)
n.
1. The bite of a snake.
2. Poisoning resulting from the bite of a venomous snake.

snakebite

Etymology: AS, snacan, to creep, bitan
a wound resulting from penetration of the flesh by the fangs or teeth of a snake. Bites by snakes known to be nonvenomous are treated as puncture wounds; those produced by an unidentified or poisonous snake require immediate attention. The bitten area should be immobilized below heart level, the patient kept still, and prompt transportation arranged to an emergency department. Only polyvalent antivenin is available for bites of all pit vipers, including rattlesnakes, copperheads, and cottonmouths. Pit vipers are responsible for 98 of the poisonous snakebites in the United States. Bites of pit vipers are characterized by pain, redness, and edema followed by weakness, dizziness, profuse perspiration, nausea, vomiting, or weak pulse; subcutaneous hemorrhage; and, in severe cases, shock. Treatment may include the use of antivenin, analgesics, antibiotics, and antitetanus prophylaxis to prevent infections from pathogens found in the mouths of snakes. Patients sensitive to horse serum in antivenin may require antihistamines and steroids for the control of hives, urticaria, and other allergic reactions. Coral snakes rarely bite, but their venom contains a neurotoxin that can cause respiratory paralysis. Antivenin and respiratory support may be indicated.

snakebite

Toxicology A bite from a snake that may be nonpoisonous
or poisonous–which may cause envenomation and, if severe, be fatal Epidemiology ± 7000 persons are bitten by poisonous snakes/yr

snakebite

injury caused by the mouthparts of a snake. (1) Cobra-type snakes inject a neurotoxin in their venom causing pupillary dilatation, excitement, convulsions and death due to asphyxia. (2) Adder-type snake venom contains also an agent that causes local swelling and necrosis. If the animal survives the neurotoxin, the part sloughs. (3) Other fractions in some venoms include hemolytic, cardiotoxic, coagulant and anticoagulant fractions. See also demansiatextilis, tiger snake, Table 22.