Tetanus: Incubation Period, Symptoms, and Management
Incubation Period
The incubation period for tetanus ranges from 3 to 21 days with a median of 7 days, though extremes of 1 day to several months have been reported. 1
- Shorter incubation periods (closer to 3 days) indicate more severe disease and carry a poorer prognosis. 2
- Longer incubation periods are associated with wounds located farther from the central nervous system. 1
- The incubation period depends on both the severity and anatomical site of the wound. 1
Clinical Symptoms and Presentation
The hallmark presentation is trismus (lockjaw) occurring in 75% of patients, followed by progressive muscle rigidity and reflex spasms. 3
Early Symptoms
- Trismus (jaw stiffness/lockjaw) is typically the first symptom, presenting in approximately 75% of cases. 3
- Neck stiffness and hypertonia develop early in the disease course. 4
- Risus sardonicus (characteristic "sardonic smile" from facial muscle spasm) may occur. 5
Progressive Manifestations
- Reflex spasms occur in 70% of patients and characterize disease severity, with spasms triggered by minor stimuli. 3
- Generalized skeletal muscle rigidity and spasms affecting the trunk and extremities. 1
- Respiratory muscle involvement leading to respiratory compromise and failure. 3
Severe Complications
- Autonomic instability (dysautonomia) occurs in approximately 70% of severe cases and is associated with high mortality. 6
- Cardiovascular disturbances including alternating bradycardia/tachycardia, labile hypertension, and potentially fatal hypotension. 7
- Rhabdomyolysis from severe muscle spasms. 8
- Pneumonia develops in approximately 85% of intensive care patients. 6
- Sudden cardiac arrest, particularly when rectal temperature exceeds 107°F (41.7°C). 7
Disease Course
- The disease course is typically intense for ≥4 weeks before subsiding. 2
- The convalescent period is protracted. 1
- Long-term neurologic sequelae and intellectual/behavioral abnormalities may follow recovery. 2
Management
Immediate Interventions
Administer Human Tetanus Immune Globulin (TIG) promptly to neutralize circulating toxin—250 units intramuscularly for prophylaxis, with higher doses (3,000-6,000 units) for established tetanus. 8
- Perform aggressive wound debridement and surgical removal of all necrotic tissue to eliminate the source of toxin production. 9, 8
- Thoroughly clean wounds to remove debris harboring Clostridium tetani spores. 9
Antimicrobial Therapy
Initiate metronidazole as the preferred antibiotic to eliminate Clostridium tetani bacteria; penicillin G is an alternative. 8
- Antibiotics eliminate the organism but do not neutralize already-produced toxin. 3
Control of Muscle Rigidity and Spasms
Diazepam may be used alone in mild cases to control muscle rigidity and spasms. 3
- Severe cases require nondepolarizing neuromuscular blocking agents plus mechanical ventilation. 3
- Continuous neuromuscular blockade is associated with increased mortality risk and should be used judiciously. 6
Respiratory Management
Early aggressive airway management with tracheostomy and mechanical ventilation is essential for severe cases, as respiratory complications occur early. 3, 7
- Hypoxemia develops in all severe tetanus patients due to ventilation-perfusion inequalities and increased venous admixture. 7
- Monitor closely for adult respiratory distress syndrome and bronchopulmonary infections. 7
Autonomic Dysfunction Management
Treat autonomic cardiovascular disturbances with combined alpha and beta blockade. 3
- Monitor for alternating bradycardia/tachycardia and labile hypertension. 7
- Persistent hypotension carries ominous significance and high mortality. 7
Supportive Care
- Maintain adequate nutrition throughout the prolonged disease course. 7
- Monitor for and aggressively manage hyperthermia, as temperatures >107°F can lead to sudden circulatory collapse. 7
- Prevent and treat sepsis, which significantly increases mortality. 7
Critical Pitfall
Do NOT administer tetanus vaccine (tetanus toxoid) to patients with active tetanus infection—it provides no benefit for treating established disease. 8
- When TIG and tetanus toxoid are given concurrently for prophylaxis, use separate syringes and injection sites. 9
Post-Recovery Immunization
Tetanus infection does not confer natural immunity; patients must complete a full primary immunization series after recovery. 2, 8
For Previously Unvaccinated Adults:
- First dose: Tdap (preferred over Td). 8
- Second dose: Td or Tdap at least 4 weeks after first dose. 8
- Third dose: Td or Tdap 6-12 months after second dose. 8
Prognosis
The case-fatality ratio remains 10-20% even in modern healthcare facilities, with mortality as high as 100% without high-quality medical care. 1, 2
- Mortality is highest in infants and elderly patients (particularly those >65 years). 2
- The case-fatality ratio in the United States declined from 18% (1998-2000) to 8% (2001-2016). 2
- Shock and multiple organ failure are the main causes of death, accounting for 73% of fatalities. 6
- Independent predictors of mortality include higher APACHE II scores, dysautonomia, continuous neuromuscular blockade, and advanced age. 6
Prevention Context
Tetanus occurs almost exclusively among unvaccinated, inadequately vaccinated, or persons with unknown vaccination histories. 1, 2