Bites of poisonous snakes

Out of 3,000 species of existing snakes, only about 15% worldwide and 20% in the US are dangerous to humans, since they have poison or poisonous salivary secretions. In every state of the United States, except Alaska, Maine and Hawaii, there is at least one natural species of a poisonous snake. Almost all of them are rattlers (also called viper vipers because of the jagged depressions on both sides of the head, which are heat-sensitive organs) and include rattlesnakes, copper snake snakes and shield muzzlers (water moccasins). Annually there are about 7000-8000 bites. Rattlesnakes bite more often than other snakes, and almost all of their bites are deadly. Most of the other poisonous bites are caused by copper snake snakes and to a lesser degree - water shield muzzles. Bites of coral snakes (aspidov) and brought varieties (in zoos, schools, snake farms, amateur and professional collections) account for less than 1% of all bites. The majority of victims are men aged 17-27 years, 50% of whom in a drunken state grabbed or teased snakes. Most often, snakes bite at their upper limbs. Every year, 5-6 deaths are recorded. The death rate is influenced by age (elderly or very young), handling of snakes kept in captivity (more important than in the case of wild snakes), delayed treatment and insufficient treatment.

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Prevalence of poisonous snakes

Habitat of snakes	Snakes
Africa	Sirloin snake
	Gabon Viper
	Earth viper
	Natal Black Snake
	Boomslang
	Snake-tarantula
	Earth viper
	Mamba
Asia	Asian Rattlesnake
	Viper Russell
	Spotted watery Asiatic
	Malaysian Rattlesnake
	Krayt
	King Cobra
Australia	Taipan
	Tiger Snake
	Brown royal
	The Deadly Serpent
	Red-bellied black
Central and South America	Rattlesnake
	Yam to the head of the adder
	Bush Master
	Coral snake
	Woody viper adder
	Mexican Shieldmound (Yamkogolovye)
Europe	Viper Convent
	Aspidian viper
	Nosed Adder
	Turkish Viper
	Touponaceous adder
Indian and Pacific Oceans	Sea Snakes
	Sea Krites
Near East	Sandy Ephah
	Horned viper
	Earth viper
	Natal Black Snake
	Earth viper
	Egyptian cobra
	Sinaitic Viper
	The Palestinian adder
North America	Rattlesnakes (for example, American or Texan rattler, horned rattlesnake, striped rattlesnake, green rattlesnake, rattlesnakes Mojave)
	Copper-clad shield muzzle
	Watermelon
	Coral snake

Pathophysiology of bites of poisonous snakes

Snake poisons are complex substances, consisting mainly of proteins that have enzymatic activity. Despite the important role of enzymes, the lethal properties of the poison can be caused by smaller polypeptides. Most of the components of the poison bind to a variety of physiological receptors, so attempts to classify poisons on effects on a particular system (eg, neurotoxin, gemotoxin, cardiotoxin, myotoxin) disorient and can cause incorrect clinical judgment.

The venom of most rattlesnakes of North America renders local action, causes coagulopathy and other systemic effects. As a result, local vascular damage, hemolysis, a syndrome similar to disseminated intravascular coagulation (ICD), pulmonary, cardiac, renal and neurologic disorders are possible. The poison changes the permeability of the capillary membrane, causing leakage of electrolytes, albumin and erythrocytes in the affected area. This process can occur in the lungs, myocardium, kidneys, abdominal cavity and less often in the central nervous system. First, edema, hypoalbuminemia, hemoconcentration develop. Later, stagnation of blood and fluid in the microcirculatory bed develops, which causes arterial hypotension, lactic acidosis, shock and, in severe cases, multiple organ failure. The effective volume of circulating blood decreases, which can cause cardiac or renal failure. After a rattlesnake bite, clinically significant thrombocytopenia (platelet count <20,000 cells per 1 μl), alone or in combination with other coagulopathies, is possible. Intravascular coagulation caused by poison can provoke an ICD syndrome with epistaxis, bleeding from the gums, hematemesis, hematuria, internal hemorrhage, and spontaneous bleeding at the site of the bite and vein puncture. The result of severe arterial hypotension, hemolysis, rhabdomyolysis, nephrotoxic action of poison or ICE can become renal failure. After a rattlesnake bite, proteinuria, hemoglobinuria and myoglobinuria are possible. The venom of most North American rattlesnakes very slightly changes the neuromuscular conductivity, with the exception of the poisons of the rattlesnake Mojave Desert and the rhombic rattler, which can cause severe neurologic disturbances.

The venom of the coral snake contains, mainly, neurotoxic components that cause presynaptic neuromuscular blockade and can cause respiratory paralysis. The lack of sufficient proteolytic enzymatic activity explains the low severity of the symptoms at the site of the snake bite.