Tetanus antitoxin is a serum that provides immediate, but temporary, passive immunity to the bacteria that cause tetanus. The antitoxin is usually given intravenously or by injection when one gets a deep wound that might be contaminated with the bacteria. It can be made with antibodies from the blood plasma of either humans or animals. If the serum is from an animal source, there is a greater risk of allergic reaction and side effects than if it is derived from humans. In some cases, the serum can also be given to animals that might be at risk for tetanus.
In most countries, humans are immunized against tetanus from birth. For those who have not received the vaccine, or if 10 years have passed since getting immunized, the tetanus antitoxin might be given to help prevent or treat tetanus. The serum provides immediate passive immunity that only lasts until the antibodies are broken down by the body, which can be anywhere from one to two weeks. It is usually administered soon after a person gets a deep wound that is vulnerable to contamination and might allow tetanus bacteria to enter the body. The antitoxin neutralizes the toxin that is released by tetanus bacteria and should be given as soon as possible after getting wounded to prevent the fatal disease from spreading throughout the body.
There are generally two processes by which a tetanus antitoxin serum could be made. One way uses pooled blood plasma from multiple humans who have been immunized. The other process involves actively immunizing an animal, typically a horse or sheep, with the tetanus toxoid so that the animal produces tetanus antibodies. The blood plasma from either the immunized human or animal sources is then separated into the globulin proteins that contain the tetanus antibodies and is made into the antitoxin serum. The serum also includes preservatives to keep the solution fresh for up to two years.
The tetanus antitoxin that is animal-derived is more likely to cause allergic reaction and side effects than one made from human blood plasma because the horse or sheep proteins are foreign to human bodies. Most times, it is preferred to use the human source antitoxin over the animal source if possible to avoid reactions. The possible reactions include anaphylaxis, serum sickness, difficulty breathing, and skin rash. The tetanus antitoxin serum from animal origins should not be used if one has asthma, infantile eczema, or has had an allergic reaction to prior serums.
In some cases, it is necessary to give animals a tetanus antitoxin. It might be given after an animal gets a deep would contaminated with soil if the animal has not been previously vaccinated against tetanus. It is also sometimes given after various operations if the animal is in a location where tetanus is a frequent problem. Like humans, animals given the tetanus antitoxin only receive temporary immunity. If the serum is being used to treat an animal that has tetanus, a higher dose is generally necessary, although it may not be successful in curing the disease.