This Publication Is Searchable The Merck Manual of Diagnosis and Therapy Section 23. Poisoning Chapter 308. In the USA, about 25 species of snakes are venomous or have toxic salivary secretions. Poisonous snakes are native to every state except Alaska, Maine, and Hawaii. Rattlesnakes account for most venomous snakebites and for almost all deaths.
Most bites occur on the extremities.
Venom Chemistry and Pathophysiology Snake venoms are complex substances, chiefly proteins, with enzymatic activity. Although enzymes play an important role, the toxic properties of the venom can be due to certain smaller polypeptides. Most venom components appear to bind with multiple physiologic receptor sites in a victim. Initially, edema, hypoalbuminemia, and hemoconcentration occur. Later, pooling of blood and fluids in the microcirculation results in shock, hypotension, and lactic acidemia.