TETANUS

also called lockjaw acute infectious disease of humans and other animals, caused by toxins elaborated by the anaerobic (living without free oxygen) bacillus Clostridium tetani and characterized by rigidity and spasms of the voluntary muscles. The almost constant involvement of the jaw muscles accounts for the popular name of the disease. Spores of Clostridium are distributed widely in nature, especially in topsoil, and may enter the body through any wound, even a superficial abrasion; puncture wounds and deep lacerations are particularly dangerous because they provide the oxygen-free environment needed for growth of the microorganism. Both the occurrence and severity of tetanus are determined by the amount of toxin produced and the resistance of the host. The neurotoxic component, tetanospasmin, is one of the deadliest poisons known. It is excreted by the bacterial cells and transported via the bloodstream from the local focus of infection to the ganglion cells of the anterior horn of the spinal cord, which are then stimulated. The neurotoxin is believed to act on the synthesis and liberation of acetylcholine, a substance having a key role in the synaptic transmission of nerve impulses throughout the body. The clinical expression of central nervous system stimulation consists of fairly constant rigidity of muscle groups, frequently and unpredictably punctuated by tonic spasms. Local tetanus, confined approximately to the area of injury, may occur as the only symptom or as a precursor to generalized affection. The incubation period is quite variable in lengthfrom two days to two weeks in most cases but sometimes up to three months. In general, the longer the incubation period, the milder will be the disease. The use of tetanus antitoxin prevents or delays the development of symptoms but is of limited value in therapy. Treatment usually includes administration of antibiotics, sedatives, and muscle relaxants. In very severe cases, curare is used. This drug paralyzes all the skeletal muscles so that they can no longer contract and thus ends the painful tonic spasms and convulsions. Because curare also paralyzes the breathing muscles, artificial ventilation becomes necessary, by means either of an iron lung or a positive-pressure machine, which blows air into the lungs through a tube inserted into the trachea. After a few weeks, when the disease is curtailed, the curare treatment is stopped and the patient begins to breathe on his own again. Passive protection with tetanus antitoxin should be administered in all cases of injuries that may be contaminated by clostridial spores. Active immunization with tetanus toxoid (prepared by chemical modification of toxin) is a relatively slow process, requiring weeks or months to become effective, and must be renewed at least every four years. A first dose should be given to every accident victim, followed by two more doses several months later. This applies also to persons who have recovered from tetanus, for an attack of the disease does not confer immunity.