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Snakes in North America are common, but venomous snakes are far more consequential elsewhere in the world. In Africa and Asia, morbidity and mortality remain far higher than in the United States, where most exposures occur among snake handlers and very effective antivenom is readily available. Recognition of the local species, protection of children, and respect for the risk associated with handling a dangerous snake limit injury. If envenomation occurs, appropriate first aid and rapid assessment help avoid substantial iatrogenic morbidity and lead to essential medical care.

Incidence of Venomous Snakebites in the United States

There are 120 species of snakes native to North America, including approximately 30 venomous species and subspecies from two families, Viperidae and Elapidae (Table 121-1). Viperidae (subfamily Crotalinae) include the rattlesnakes (genera Crotalus and Sistrurus) along with the copperheads and water moccasins (genus Agkistrodon). The vast majority of venomous snakebites in the United States that occur annually are from Crotalinae, with about 55% of these being rattlesnake bites and the rest from copperheads and water moccasins. The other family of venomous snakes native to the United States is the Elapidae, which includes the coral snakes. Fewer than 5% of poisonous snakebites are from the coral snake.6

Table 121–1. Medically Important North American Snakes

Venomous snakes are found throughout the United States, except Maine, Alaska, and Hawaii. They are common in the Appalachian states, the South, and the West but are rare in New England and the northern states. There are approximately 6000 to 8000 venomous snakebites per year in the United States. Mortality from snakebite is considered to be quite rare in the United States, with estimates ranging from five to 15 deaths per year.25 Exact statistics are lacking, but mortality rates can be significantly higher in other countries. There may be as many as 27,000 rattlesnake bites and 100 fatalities per year in Mexico14 and thousands of deaths per year in some Southeast Asian and African countries.

Because snakes hibernate in the winter, most bites in the United States occur between May and October. Snakebites may occur at night, but the most common time for envenomation is from 2 ...

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