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A tetanus toxin is a toxin produced by Clostridium tetani bacteria. One toxin in particular is of medical concern because it causes muscle spasms in victims, although several other toxins are also produced by these common bacteria. Tetanus toxin causes the distinctive symptoms known as "tetanus" and can be fatal in some cases. It is also used in the production of a toxoid used to create resistance to tetanus infections. The widespread use of tetanus vaccinations has greatly reduced the incidence of tetanus.
These bacteria are naturally found in soils all over the world. Bacterial toxins often have a function for the bacteria, but in the case of tetanus toxin, there is no known function. The toxin is released when individual bacteria die and break up. In the soil, it dissipates harmlessly, but if the bacteria happen to be colonizing an injury, the toxin travels through the blood and lymph of the body.
Tetanus toxin is a neurotoxin, with an affinity for nerve cells. It works by blocking the release of GABA, a neurotransmitter with inhibitory effects. When GABA release is blocked, the muscles can go into spasm. Since tetanus toxin strikes short nerves first, the first sign of tetanus is usually stiffness and spasm in the muscles of the face. An alternate term for tetanus is “lockjaw,” referring to one of the hallmark spasms associated with the condition.
As tetanus toxin spreads through the body, more nerves are involved and additional muscles can go into spasm. This can be extremely painful for the patient. In some cases, spasms are so severe that the bones of the body are broken, especially long bones like the femur. The airways can close down, causing the patient to die as a result of not getting enough oxygen. Treatments for tetanus include administrations of antitoxin, supportive therapy, and antibiotics.
When the tetanus toxin is used in the production of a toxoid, it can become a valuable tool for medical treatment and disease prevention. Toxoids are treated bacterial toxins with reduced virulence. Vaccination for tetanus provides the immune system with some resistance. Vaccinations are recommended every 10 years or in situations where someone may be at risk of tetanus infection as a result of an injury.
The Clostridium genus contains a number of other species known to pose a threat to human health. Infections with these bacteria can cause a variety of symptoms, depending on the species and the severity of the infection.