Information AboutAntivenom |
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THERAPEUTIC USE Antivenoms typically need to be administered as soon as possible after the venom has been injected to be effective (up to 4-5 hours). Since the advent of antivenoms, some bites which were previously inevitably fatal have become only rarely fatal provided that the antivenom is administered soon enough. The antivenin is usually purified by several processes but still may contain other serum Proteins that can act as Antigen s. Some individuals may react to the antivenin with an immediate hypersensitivity reaction ( Anaphylaxis ) or a delayed hypersensitivity ( Serum Sickness ) reaction and antivenin should, therefore, be used with caution. Antivenins can be classified into monovalent (when they are effective against a given species' venom) or '''polyvalent''' (when they are effective against a range of species, or several different species at the same time). Antivenins for therapeutic use are usually preserved as Freeze-dried ampules and must be injected intramuscularly to achieve effect, but some of them are available only in liquid form and must be preserved in a Cold Chain . The principle of antivenim was based on that of Vaccine s, developed by Louis Pasteur . The first antivenom for snakes (called an anti-ophidic serum) was discovered by Albert Calmette , a French scientist of the Pasteur Institute working at its Indochine branch in 1895, against the Indian Naja Snake . Vital Brazil , a Brazilian scientist developed in 1901 the first monovalent and polyvalent antivenoms for Central and South American '' Crotalus '', '' Bothrops '' and '' Elaps '' genera, as well as for certain species of venomous Spider s, Scorpion s and Frog s. They were all developed in a Brazilian institution, the Instituto Butantan , located in São Paulo , Brazil . AVAILABILITY OF ANTIVENOMS Antivenom have been developed for the venoms associated with the following animals: Spiders
Snakes
No antivenom is yet available against Tetrodotoxin , produced by the Blowfish . ANTIVENOM SOURCES The following groups assist in locating antivenins:
NATURAL AND ACQUIRED IMMUNITY Although individuals can vary in their physiopathological response and sensitivity to animal venoms, there is no natural immunity to them in humans. Some Ophiophagic animals are immune to the venoms produced by some species of venomous snakes, by the presence of antihemorrhagic and antineurotoxic factors in their blood. These animals include King Snakes , Opossums and Hedgehogs . In theory, immunity can be acquired by humans by administering small and graded doses of venom (according to Greek Mythology , King Mithridates did this in order to protect himself against attempts of Poisoning , therefore this procedure is often called '' Mithridatization ''). There is, however, no practical purpose or favorable cost/benefit ratio for this, except for people like Zoo handlers, researchers, and circus artists who deal closely with venomous animals. Mithridatization has been tried with success in Australia and Brazil and total immunity has been achieved even to multiple bites of extremely venomous cobras and pit vipers. Bill Haast successfully immunized himself to the venoms of a number of species of poisonous snakes. EXTERNAL LINK
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