Tetanus in Emergency Medicine
- Author: Daniel J Dire, MD, FACEP, FAAP, FAAEM; Chief Editor: Rick Kulkarni, MD more...
Background
Tetanus is an illness characterized by an acute onset of hypertonia, painful muscular contractions (usually of the muscles of the jaw and neck), and generalized muscle spasms without other apparent medical causes.
Although records from antiquity (5th century BC) contain descriptions of tetanus, it was Carle and Rattone in 1884 who first produced tetanus in animals. This was accomplished by injecting them with pus from a fatal human tetanus case. During that same year, Nicolaier produced tetanus in animals by injecting them with soil. In 1889, Kitasato isolated the organism from an infected human, showed that it produced disease when injected into animals, and reported that the toxin could be neutralized by specific antibodies. In 1897, Nocard demonstrated the protective effect of passively transferred antitoxin. Passive immunization in humans was used for treatment and prophylaxis during World War I. Tetanus toxoid was developed by Descombey in 1924. It was first widely used during World War II.
Despite widespread immunization of infants and children in the United States since the 1940s, tetanus still occurs in the United States. Currently, tetanus is a severe disease primarily of older adults who are unvaccinated or inadequately vaccinated. Worldwide, most reported cases of tetanus are the neonatal type. The last reported case of neonatal tetanus in the United States was in 1998; this was only the second case since 1989, and neither of the mothers had ever received tetanus vaccinations.
For more information, see Medscape's Vaccine Resource Center.
Pathophysiology
Clostridium tetani, an obligate anaerobic gram-positive bacillus, causes tetanus. This bacterium is nonencapsulated and forms spores, which are resistant to heat, desiccation, and disinfectants. The spores are ubiquitous and are found in soil, house dust, animal intestines, and human feces.
Spores that gain entry can persist in normal tissue for months to years. Under anaerobic conditions, these spores geminate and elaborate tetanospasmin and tetanolysin. Tetanolysin is not believed to be of any significance in the clinical course of tetanus. Tetanospasmin is a neurotoxin and causes the clinical manifestations of tetanus. Tetanospasmin that is released by the maturing bacilli is distributed via the lymphatic and vascular circulations to the end plates of all nerves. Tetanospasmin then enters the nervous system peripherally at the myoneural junction and is transported centripetally into neurons of the central nervous system (CNS). Per weight, tetanospasmin is one of the most potent toxins known. The estimated minimum lethal dose is 2.5 nanograms per kilogram of body weight (a nanogram is one billionth of a gram), or 175 nanograms for a 70-kg (154-lb) human.
These neurons become incapable of neurotransmitter release. The neurons, which release gamma-aminobutyric acid (GABA) and glycine, the major inhibitory neurotransmitters, are particularly sensitive to tetanospasmin, leading to failure of inhibition of motor reflex responses to sensory stimulation. This results in generalized contractions of the agonist and antagonist musculature characteristic of a tetanic spasm. The shortest peripheral nerves are the first to deliver the toxin to the CNS, which leads to the early symptoms of facial distortion and back and neck stiffness.
Once the toxin becomes fixed to neurons, it cannot be neutralized with antitoxin. Recovery of nerve function from tetanus toxins requires sprouting of new nerve terminals and formation of new synapses.
Epidemiology
Frequency
United States
Reported incidence of tetanus has declined substantially since the mid 1940s because of the widespread use of tetanus immunizations (see the graph below).
Tetanus Cases in US from 1947-2005. From Tetanus and Tetanus Toxoid: Epidemiology and Prevention of Vaccine-Preventable Diseases. National Immunization Program, Centers for Disease Control and Prevention. January 2006. The reported number of tetanus cases and average annual incidence rates, by state, in the United States from 1998-2000 are shown in the chart below. An average of 43 cases was reported annually. Some suggest that only 40% of tetanus cases are reported to the Centers for Disease Control and Prevention (CDC).
Image from "Number of Tetanus Cases Reported and Average Annual Incidence Rates, by State." Pascual FB, McGinley EL, Zanardi LR, et al: Tetanus surveillance--United States, 1998--2000. MMWR Surveill Summ. 2003 Jun 20; 52(3): 1-8. The number of tetanus cases reported, average annual incidence rates, and survival status of patients, by age group, from 1998-2000 are shown in the graph below. The lowest average annual number of cases for a 3-year period in the United States was 41 cases per year during 1995-1997.
Image from "Number of Tetanus Cases Reported, Average Annual Incidence Rates, and Survival Status of Patients, by Age Group." Pascual FB, McGinley EL, Zanardi LR, et al: Tetanus surveillance--United States, 1998--2000. MMWR Surveill Summ. 2003 Jun 20; 52(3): 1-8. Of the 130 cases of tetanus reported in the United States from 1998-2000, California and Texas had the highest reported number of cases. All 50 states require that children be vaccinated prior to admission to public schools. More than 96% of children have received 3 or more diphtheria and tetanus toxoids plus pertussis (DTP) vaccinations by the time they begin school. The annual incidence of tetanus has dropped to fewer than 50 cases per year in the United States.
Heroin users, particularly persons who inject themselves subcutaneously, appear to be at high risk for tetanus. Quinine is used to dilute heroin and may support the growth of C tetani. The incidence of tetanus in people who use injection drugs increased 7.4%, from 3.6% of all cases in 1991-1994 to 11% of cases in 1995-1997. People who use injection drugs accounted for 15% of the tetanus cases in the United States from 1998-2000 (see the graph below). Of the 19 people who used injection drugs and contracted tetanus from 1998-2000, only 1 reported an acute injury.
Image from "Number of Tetanus Cases Reported Among Persons With Diabetes or Injection-Drug Use (IDU), by Age Group." Pascual FB, McGinley EL, Zanardi LR, et al: Tetanus surveillance--United States, 1998--2000. MMWR Surveill Summ. 2003 Jun 20; 52(3): 1-8. Most tetanus cases occur among people who are inadequately vaccinated and who sustain an acute injury.
International
Worldwide, tetanus is predominantly a disease of underdeveloped countries located in warm, damp climates. Tetanus affects all age groups, with the highest prevalence found in newborns and young people. In 1992, an estimated 578,000 infant deaths occurred due to neonatal tetanus. In 1998, 215,000 deaths occurred with more than 50% of these on the Africa continent. Tetanus is one of the target diseases of the World Health Organization (WHO) Expanded Program on Immunization. Overall, the annual incidence of tetanus is 0.5-1 million cases. WHO estimated there were 213,000 tetanus deaths in 2002 with 198,000 occurring in children younger than 5 years.
Developed nations have incidences of tetanus similar to those observed in the United States. For instance, only 126 cases of tetanus were reported in England and Wales in 1984-1992.
Mortality/Morbidity
Overall, the mortality rate is approximately 45%. Clinical tetanus is less severe among patients who have a history of receiving a primary series of tetanus toxoid sometime during their life as compared with patients who are inadequately vaccinated or unvaccinated. The mortality rate in the United States is 6% for individuals who had previously received 1-2 doses of tetanus toxoid compared with 15% for individuals who were unvaccinated.
- The case-fatality ratio in the United States was 18% from 1998-2000 and 11% from 1995-1997; a case-fatality ratio of 91% was reported in 1947.[1]
- The mortality rate is highest for people older than 60 years (40%) compared with those aged 20-59 years (8%). From 1998-2000, 75% of the deaths in the United States were in patients older than 60 years.[1]
- The mortality rate is 30% for people who require mechanical ventilation but only 4% for those who do not.
Race
From 1998-2000, the incidence of tetanus in the United States was highest among Hispanics (0.38 cases per million population), followed by whites (0.13 cases per million population), and then African Americans (0.12 cases per million population).[1]
Sex
A difference in the levels of tetanus immunity exists between the sexes.
- Overall, men are believed to be better protected than women, perhaps because of additional vaccinations administered during military service or professional activities.
- In the United States from 1998-2000, the incidence of tetanus in males aged 59 years and younger was 2.8 times higher than in females in the same age range.
- In developing countries, women have an increased immunity where tetanus toxoid is administered to women of childbearing age to prevent neonatal tetanus.
Age
The incidence of tetanus increases with advancing age. From 1980 through 2000, 70% of reported cases of tetanus in the United States were among persons aged 40 years or older. Of all these patients, 36% are older than 59 years and only 9% are younger than 20 years.
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