Tetanus is an acute disease manifested by skeletal muscle spasm and autonomic nervous system disturbance. It is caused by a powerful neurotoxin produced by the bacterium Clostridium tetani and is completely preventable by vaccination. C. tetani is found throughout the world, and tetanus commonly occurs where the vaccination coverage rate is low. In developed countries, the disease is seen occasionally in individuals who are incompletely vaccinated. In any setting, established tetanus is a severe disease with a high mortality rate.
Tetanus is diagnosed on clinical grounds (sometimes with supportive laboratory confirmation of the presence of C. tetani; see “Diagnosis,” below), and case definitions are often used to facilitate clinical and epidemiologic assessments. The Centers for Disease Control and Prevention (CDC) defines probable tetanus as “an acute illness with muscle spasms or hypertonia in the absence of a more likely diagnosis.” Neonatal tetanus is defined by the World Health Organization (WHO) as “an illness occurring in a child who has the normal ability to suck and cry in the first 2 days of life but who loses this ability between days 3 and 28 of life and becomes rigid and has spasms.” Given the unique presentation of neonatal tetanus, the history generally permits accurate classification of the illness with a high degree of probability. Maternal tetanus is defined by the WHO as tetanus occurring during pregnancy or within 6 weeks after the conclusion of pregnancy (whether with birth, miscarriage, or abortion).
C. tetani is an anaerobic, gram-positive, spore-forming rod whose spores are highly resilient and can survive readily in the environment throughout the world. Spores resist boiling and many disinfectants. In addition, C. tetani spores and bacilli survive in the intestinal systems of many animals, and fecal carriage is common. The spores or bacteria enter the body through abrasions, wounds, or (in the case of neonates) the umbilical stump. Once in a suitable anaerobic environment, the organisms grow, multiply, and release tetanus toxin, an exotoxin that enters the nervous system and causes disease. Very low concentrations of this highly potent toxin can result in tetanus (minimal lethal human dose, 2.5 ng/kg).
In 20–30% of cases of tetanus, no puncture entry wound is found. Superficial abrasions to the limbs are the most common infection sites in adults. Deeper infections (e.g., attributable to open fracture, abortion, or drug injection) are associated with more severe disease and worse outcomes. In neonates, infection of the umbilical stump can result from inadequate umbilical-cord care; in some cultures, for example, the cord is cut with grass or animal dung is applied to the stump. Circumcision or ear-piercing also can result in neonatal tetanus.
Tetanus is a rare disease in the developed world. Two cases of neonatal tetanus have occurred in the United States since 1989. In 2013, 26 cases ...