INTRODUCTION AND EPIDEMIOLOGY
Tetanus is uncommon in the United States but continues to have a substantial health impact in developing countries. The worldwide incidence of tetanus is approximately 1 million cases per year, with a mortality rate of 20% to 30%.1
The Centers for Disease Control and Prevention defines tetanus as a syndrome of acute onset of hypertonia and/or painful muscular contractions (usually of the muscles of the jaw and neck) and generalized muscle spasms without other apparent medical cause as reported by a health professional.2 In the United States, tetanus is a reportable disease, aggregated through the National Notifiable Diseases Surveillance System.
Improved childbirth practices, widespread immunization programs for children, decennial tetanus boosters for adults, mechanization of agriculture, and use of chemical fertilizers rather than animal manure have resulted in a >95% decline in the annual incidence of tetanus in the United States since 1947.2 From 2001 to 2008, 233 tetanus cases were reported in the United States from 45 states, with the majority of cases reported from five states: California (n = 60), Florida (n = 25), Texas (n = 12), New York (n = 12), and Pennsylvania (n = 11).2 Most patients who develop tetanus have inadequate immunity to the disease. Due to waning immunity and failure to receive routine boosters, only 31% of Americans >70 years old have adequate tetanus immunity.3 As a result, the average annual incidence of tetanus among those ≥65 years of age is higher (0.23 cases per 1 million population) than among those age 5 to 64 years (0.08 cases per 1 million population). Tetanus among children and neonatal tetanus are uncommon in the United States as well as in other developed countries. The case fatality rate is approximately 13%, with the elderly accounting for the majority of deaths.2
Most cases of tetanus in the United States are associated with an acute wound. Puncture, contaminated, infected, or devitalized wounds account for approximately 70% of tetanus cases. Although less common, chronic wounds, ulcers and other wounds in diabetics, and dental abscesses are also associated with the disease. Diabetics and injection drug users have an increased risk of contracting tetanus.2,4
Most patients who develop tetanus do not seek medical care for their initial wound. In those who do seek initial treatment and later develop tetanus, up to 95% do not receive appropriate therapy.2
Clostridium tetani is a motile, nonencapsulated, anaerobic gram-positive rod, and its toxins cause tetanus. C. tetani exists in either a vegetative or a spore-forming state. The spores are ubiquitous in soil and in animal feces and are resistant to destruction, surviving on environmental surfaces for years. In agricultural areas, adults may harbor the organism, and spores have been found on skin or in contaminated heroin.4,5 C. tetani is usually introduced into ...