Although rust itself does not cause tetanus, objects that accumulate rust are often found outdoors or in places that harbor anaerobic bacteria. Additionally, the rough surface of rusty metal provides crevices for dirt containing C. tetani, while a nail affords a means to puncture skin and deliver endospores deep within the body at the site of the wound. An endospore is a non-metabolizing survival structure that begins to metabolize and cause infection once in an adequate environment. Hence, stepping on a nail (rusty or not) may result in a tetanus infection, as the low-oxygen (anaerobic) environment may exist under the skin, and the puncturing object can deliver endospores to a suitable environment for growth. It is a common misconception that rust itself is the cause and that a puncture from a rust-free nail is not a risk. Pathophysiology
Tetanus neurotoxin (TeNT) binds to the presynaptic membrane of the neuromuscular junction, is internalized and is transported back through the axon until it reaches the central nervous system. Here, it selectively binds to and is transported into inhibitory neurons via endocytosis. It then leaves the vesicle for the neuron cytosol where it cleaves vesicle associated membrane protein (VAMP) synaptobrevin, which is necessary for membrane fusion of small synaptic vesicles (SSVs). SSVs carry neurotransmitter to the membrane for release, so inhibition of this process blocks neurotransmitter release.Tetanus toxin specifically blocks the release of the neurotransmitters GABA and glycine from inhibitory neurons.
Tetanus, also known as lockjaw, is a bacterial infection caused by Clostridium tetani, and is characterized by muscle spasms. In the most common type, the spasms begin in the jaw and then progress to the rest of the body. Each spasm usually lasts a few minutes. Spasms occur frequently for three to four weeks. Some spasms may be severe enough to fracture bones. Other symptoms of tetanus may include fever, sweating, headache, trouble swallowing, high blood pressure, and a fast heart rate. Onset of symptoms is typically three to twenty-one days following infection. Recovery may take months. About ten percent of cases prove to be fatal.C. tetani is commonly found in soil, saliva, dust, and manure. The bacteria generally enter through a break in the skin such as a cut or puncture wound by a contaminated object. They produce toxins that interfere with normal muscle contractions. Diagnosis is based on the presenting signs and symptoms. The disease does not spread between people.Tetanus can be prevented by immunization with the tetanus vaccine. In those who have a significant wound and have had fewer than three doses of the vaccine, both vaccination and tetanus immune globulin are recommended. The wound should be cleaned and any dead tissue should be removed. In those who are infected, tetanus immune globulin or, if unavailable, intravenous immunoglobulin (IVIG) is used. Muscle relaxants may be used to control spasms.