Antivenom (or also called antivenin) is a biological product used in the treatment of venomous snake bites or stings. Antivenom is developed by milking venom from the specific snake, or in other cases an insect or spider. The venom is diluted and injected into either a horse, sheep or goat. That animal will be subjected to an immune response to the venom, producing antibiodies against the venom which can then be acquired from the animal’s blood and used to treat the envenomation.
The name “antivenin” comes from the French word venin, meaning venom, which came from the latin word venenum, meaning poison. While both words are accepted, in North America, the more common term used is antivenom.
The foundation of antivenom is based on the idea of vaccines, however, instead of inducing immunity in the patient directly, it is induced in a host animal and the immunized serum is transfused into the patient.
Antivenom can be classified into two categories. A monovalent is an antivenom that is effective against only one species’ venom. A polyvalent is an antivenom that is effective against more than one species. North American Rattlesnake bites (pit viper bites) use a monovalent called CroFab, that will be effective against all the rattlesnakes you will encounter in San Diego County. If you are bitten by a rattlesnake in San Diego County, the hospital is likely to have the antivenom on hand. Antivenoms for exotic or non-local snake bites will usually have to be rushed in from a local zoo or institution that carries the particular antivenom that is needed for the species you were bit by as hospitals don’t usually keep these on hand. It is especially important to get to a hospital as soon as possible and describe what you were bit by to the doctor, so that the correct treatment can be applied quickly to avoid further damage or death.
Antivenoms bind to and neutralize the venom, halting further damage, but do not reverse damage already done. Thus, they should be administered as soon as possible after the venom has been injected. Since the advent of antivenoms, some bites which were previously invariably fatal have become only rarely fatal provided that the antivenom is administered soon enough.
CroFab® Crotalidae Polyvalent Immune Fab (Ovine) is a treatment for the management of patients with North American pit viper envenomations. CroFab® polyvalent has been clinically proven to halt envenomation progression from venomous North American pit viper bites (rattlesnake).
Early use of CroFab® (within 6 hours of snakebite) is advised to prevent further deterioration.
What is the difference between a “venom” and a “poison”? A venom is a toxin that has been administered through an injection (like a snake bite). A poison is a toxin that is ingested or administered topically (like rat poison or pesticides). These terms are often incorrectly used interchangeably.
Every venomous snake species has a unique type of venom (enzyme mixtures are all a little bit different). Most of their venoms fall into one (or more) of three categories:
- Hemotoxic — This type of venom attacks blood cells and the cardiovascular system. It can also cause a lot of tissue damage (often permanent damage) in the vicinity of the bite. This type of toxic is particularly painful, and can lead to death, if left untreated. Rattlesnakes fall into this venom category.
- Neurotoxic — This type of venom attacks the victim’s nervous system and brain. Death can be caused by heart failure and respiratory failure. Venomous snakes that possess neurotoxins include elapids ( the cobras, coral snakes, and mambas).
- Cytotoxic — This word can be literally translated as “toxic to cells.” This venom causes cellular damage in the location of the bite. It can cause necrosis, or tissue death, as well. The majority of vipers (including rattlesnakes) fall into this category.