Normally, transmission occurs through a puncture wound that’s contaminated by soil, dust, or animal excreta containing C. tetani or by way of burns and minor wounds. After C. tetani enters the body, it causes local infection and tissue necrosis. It also produces toxins that then enter the bloodstream and lymphatics and eventually spread to central nervous system tissue.

Tetanus occurs worldwide but is more prevalent in agricultural regions and in developing countries that lack mass immunization programs. It’s one of the most common causes of neonatal death in developing countries, where infants of nonvaccinated mothers are delivered under nonsterile conditions. In these infants, the unhealed umbilical cord is the portal of entry.

In the United States, about 75% of all tetanus cases occur between April and September.

Atelectasis, pneumonia, pulmonary emboli, acute gastric ulcers, seizures, flexion contractures, and cardiac arrhythmias can result from tetanus.

The incubation period ranges from 3 to 4 weeks in mild tetanus to less than 2 days in severe tetanus. Death is more likely when symptoms occur within 3 days following injury. If tetanus remains localized, signs of onset are spasm and increased muscle tone near the wound. Indications of generalized (systemic) tetanus include marked muscle hypertonicity, hyperactive deep tendon reflexes, tachycardia, profuse sweating, low-grade fever, and painful, involuntary muscle contractions: