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Tetanus, an acute infectious noncontagious disease caused by Clostridium tetani, is characterized by a prolonged illness associated with severe complications, including death. In industrialized countries, tetanus primarily affects elderly adults, while in developing countries, neonatal tetanus predominates and is a substantial major contributor to infant mortality. Elimination of tetanus, especially neonatal tetanus, through vaccination is a global public health priority.

CLINICAL DESCRIPTION

Tetanus (lockjaw) is an acute neurologic disease that occurs when C. tetani spores infect a site of injury and produce a neurotoxin. Wounds accompanied by tissue injury and necrosis produce the anaerobic conditions necessary for bacterial replication and toxin production. The diagnosis is usually established clinically and supported by the epidemiologic setting. Major symptoms are spasm of the muscles of mastication (trismus or lockjaw) and generalized hyperreflexia, which produces painful and uncontrollable muscular contractions. Generalized spasms can occur, often induced by external sensory stimuli. The incubation period ranges from two days to two months, with an average of ten days. The course of illness may last several weeks (often requiring intubation) and subsides gradually in survivors.

The case fatality rate ranges between 10 and 90 percent. Survival is correlated with longer incubation periods and access to medical care. Shorter incubation periods are usually associated with heavily contaminated wounds, more serious disease, and worse outcomes. A wound history can be established in approximately 80 percent of tetanus patients in the United States; however, absence of a wound does not rule out tetanus. Laboratory confirmation of tetanus is difficult and may not be definitive. Culture of the wound may rarely yield C. tetani; serology is often not helpful because disease can be caused by quantities of toxin insufficient to induce an immune response.

Neonatal tetanus (NT) is caused by unsanitary conditions during childbirth, specifically contamination of the umbilical stump. Neonatal tetanus can be prevented by education about the need for clean deliveries and immunization of women of childbearing age (including pregnant women).

EPIDEMIOLOGY

Clostridium tetani is a normal inhabitant of soil and of animal and human intestines and occurs worldwide. Cases increase during warmer months in temperate climates, most likely because of increased outdoor activity. In the United States, an average of forty-six tetanus cases per year were reported to the Centers for Disease Control and Prevention (CDC) from 1990 to 1999, as compared to an average of sixty-seven cases in the 1980s.

In developing countries, neonatal tetanus is a leading cause of neonatal mortality, accounting for over 250,000 deaths annually. Neonatal tetanus has been called "the silent killer," since infants often die before their birth is recorded.

CONTROL MEASURES

In the United States, five doses of tetanus toxoid are recommended at 2, 4, 6, and 18 months and between 4 and 6 years of age, most often administered with diphtheria toxoid and acellular pertussis vaccine (DTaP). Subsequent booster shots for tetanus, combined with diphtheria toxoid, are recommended every ten years. Less than one percent of tetanus cases recently reported in the United States were in persons with up-to-date immunizations.

There is no herd immunity for tetanus since C. tetani is not transmitted from person to person. Although tetanus is a highly preventable disease, all individuals remain at risk if they do not acquire and maintain immunity through vaccination and periodic boosters.

ELIZABETH FAIR

ROLAND SUTTER

(SEE ALSO: Communicable Disease Control; Immunizations)