It is now well established that TeNT is the sole cause of tetanus, though it took many centuries to establish a direct mechanistic link between the neurotoxin and the disease it causes. In fact, tetanus was first described in medical terms by Hippocrates, who defined this paralysis as "tetanus" (tetavoo in Greek means contraction). Tetanus may develop in different forms, and the most common one is the generalized tetanus caused by contamination of even minor wounds or skin scratches with spores of toxigenic Clostridium tetani. Between the time of injury and the first symptoms there is a lag phase varying from few days up to four weeks, which corresponds to the time necessary for (1) germination of spores, (2) toxin production and release, and (3) toxin diffusion, binding, transport to its target cells within the spinal cord. Tetanus usually begins with a characteristic lockjaw (risus sardonicus), with difficulty in swallowing and neck stiffness (Bleck 1989). With time, the muscle paralysis extends downwards to the muscles of the trunk, abdomen, and legs. The typical tetanic seizure is characterized by a sudden burst of tonic contraction of skeletal muscles with extension to the lower extremities. Seizures are very painful and can be triggered by minor stimuli such as a small light or noise, with the patient remaining completely conscious during such episodes. Later on, autonomic symptoms develop with alterations of blood pressure and of the cardiac rhythm and sweating. Dysphagia and glottal and laryngeal spasm may cause cyanosis and asphyxia, which can be relieved by tracheotomy and mechanically assisted respiration.
A milder form of the disease is local tetanus, with rigidity of the muscles close to the site of injury and release of the toxin. This local tetanus may persist for a considerable period of time without further developments or it may proceed to generalized tetanus. It is due to dysfunction of the spinal cord inhibitory interneurons which inhibit the alpha motor neurons of the affected muscles, with little, if any, further spread through the central nervous system. Tetanus is often fatal, and death follows body exhaustion and usually intervenes by respiratory failure or heart failure (Bleck 1989). The mortality has decreased owing to modern intensive care techniques, but it is still high because of the usually advanced age of patients and because their respiration has to be mechanically assisted for long periods of time with the risk of developing pulmonary infections. Following vaccination with tetanus tox-oid (formaldehyde-treated tetanus toxin), tetanus has almost disappeared from the more developed countries, but it still takes hundreds of thousand of lives in those regions of the world where vaccination is not performed (Galazka and Gasse 1995). Here, the major form of tetanus is tetanus neonatorum, which develops following the nonsterile cut of the umbilical cord of babies born from nonimmunized mothers. This condition is prevalent in communities that employ traditional midwifery practices such as cutting the cord with dirty scissors or rubbing manure on the umbilical stump.
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