Bites by venomous snakes result in a wide range of effects. They range from simple puncture wounds to life-threatening illness and death. The findings following a venomous snakebite can be misleading. A victim can have no initial significant symptoms, and then suddenly develop breathing difficulty and go into shock.
Signs and symptoms of snakebites can be broken into a few major categories:
- Local effects: These are the effects on the local skin and tissue
surrounding the bite area. Bites by vipers and some cobras (Naja and other genera) are painful and tender. They can be severely swollen and can bleed and blister. Some cobra venoms can also kill the tissue around the site of the bite.
- Bleeding: Bites by vipers and some Australian elapids can cause
changes in the victim's hematologic system causing bleeding. this bleeding can
be localized or diffuse. Internal organs can be involved. A victim may bleed from the bite site or bleed spontaneously from the mouth or old wounds. Unchecked bleeding can cause shock or even death.
- Nervous system effects: The effect on the nervous system can
be experienced locally close to the bite area or affect the nervous system
directly. Venom from elapids and sea snakes can affect the nervous system directly. Cobra (Naja and other genera) and mamba (Dendroaspis) venom can act particularly quickly by stopping the breathing muscles, resulting in death without treatment. Initially, victims may have vision problems, speaking and breathing trouble, and numbness
close to or distant to the bite site.
- Muscle death: Venom from Russell's vipers (Daboia russellii), sea snakes, and some Australian elapids can directly cause muscle death in multiple areas of the body.
There can be local effect of muscle death (necrosis), or distant muscle
involvement (rhabdomyolysis). The debris from dead muscle cells can clog the kidneys, which try to filter out the proteins. This can lead to
- Eyes: Spitting cobras and ringhals (cobralike snakes from Africa) can actually eject their venom quite accurately into the eyes of their victims, resulting in direct eye pain and damage.
Spitting cobra bite. Many elapid bites result in little local swelling, but the spitting cobras are known for the amount of swelling and tissue damage they can cause. Photograph by Clyde Peeling.
Western diamondback rattlesnake (Crotalus atrox) bite. Rattlesnake bites can cause severe swelling, pain, and permanent tissue damage. Photograph by Clyde Peeling.
Copperhead (Agkistrodon contortrix) bite. These bites usually result in local pain and swelling but usually have less tissue loss than rattlesnake bites. Photograph by Tom Diaz.
Timber rattlesnake (Crotalus horridus) bite. Pit viper bites can cause a leakage of blood cells out of the blood vessels, even on parts of the body away from the bite site. Note the significant bruising of the upper forearm and arm. Photograph by Clyde Peeling.
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