Tetanus is usually known as ‘lockjaw’ because there may be difficulty in opening the mouth, although this is simply part of a spasm of all the muscles of the body.
Caused by bacterium, clostridium tetani, lockjaw—properly called tetanus—leads to rigidity and involuntary-muscle spasms that become progressively more violent and uncontrolled. The symptoms often arise first in the jaw, thus giving the disease its sobriquet.
Tetanus bacteria (see the microscopic picture below) spores are prevalent in topsoil, so any open would is susceptible to infection. Because clostridium tetanis anaerobic—it can live only in an environment that lacks oxygen—wounds with poor blood circulation are the most vulnerable. Thus, in an unfavorable medium, the hardy spores ensure that bacteria’s survival for
months or years.
When the bacteria find an anaerobic region of injured tissue, they incubate and then begin to reproduce and secrete tetanospasmin, one of the deadliest toxins known. Tetanospasmin travels from the injury site, perhaps via nearby nerves or the bloodstream, to neurons in the spinal cord. There the toxin is thought to back the release of certain neurotransmitters, causing muscle spasms all over the body. Eventually, even inconsequential noises or draughts can trigger the convulsions, which arch the body so that only the victim’s head and feet touch an underlying surface. See the photo above.
The severity of tetanus can be lessened by a quick dose of an antitoxin that neutralises any tetanospasmin being released; sedatives, muscle relaxants and antibiotics are also prescribed.
Tetanus can be prevented, however, by immunisation with tetanus toxoid, toxin that has been chemically inactivated so that it won’t harm the nervous system but will cause antibody formation in the recipients’ bloodstream. The treatment takes weeks or months to become effective and is maintained by ‘booster’ injections every 10 years, unless a wound in the interim requires care.