Tetanus

Clinical Description

Identification

An acute disease induced by an exotoxin of the tetanus bacillus, which grows anerobically at the site of an injury. The disease is characterized by painful muscular contractions, primarily of the masseter and neck muscles, secondarily of trunk muscles. A common first sign suggestive of tetanus in older children and adults is abdominal rigidity, though rigidity is sometimes confined to the region of injury. Generalized spasms occur, frequently induced by sensory stimuli; typical features of the tetanic spasm are the position of opisthotonos and the facial expression known as “risus sardonicus.” History of an injury or apparent portal of entry may be lacking. Case-fatality rate ranges from 10% to over 80% depending on age and quality of care available, is highest in infants and the elderly, and varies inversely with the length of the incubation period and the availability of experienced intensive care unit personnel and resources.

Infectious Agent

Clostridium tetani, the tetanus bacillus.


Diagnosis

Attempts at laboratory confirmation are of little help. The organism is rarely recovered from the site of infection, and usually there is no detectable antibody response.
 


Epidemiology

Mode of Transmission

Tetanus spores are usually introduced into the body through a puncture wound contaminated with soil, street dust or animal or human feces; through lacerations, burns and trivial or unnoticed wounds; or by injected contaminated drugs (e.g. street drugs). Tetanus occasionally follows surgical procedures, which include circumcision and abortions performed under unhygienic conditions. The presence of necrotic tissue and/or foreign bodies favors growth of the anerobic pathogen. Cases have followed injuries considered too trivial for medical consultation.

Incubation Period

Usually 3–21 days, although it may range from 1 day to several months, depending on the character, extent and location of the wound; average 10 days. Most cases occur within 14 days. In general, shorter incubation periods are associated with more heavily contaminated wounds, more severe disease, and a worse prognosis.

Period of Communicability

No direct person-to-person transmission.

Reservoir

Intestines of horses and other animals, including humans, in which the organism is a harmless normal inhabitant. Soil or fomites contaminated with animal and human feces. Tetanus spores, ubiquitous in the environment, can contaminate wounds of all types.

Susceptibility and Resistance

Susceptibility is general. Active immunity is induced by tetanus toxoid and persists for at least 10 years after full immunization; transient passive immunity follows injection of tetanus immune globulin (TIG) or tetanus antitoxin (equine origin). Infants of actively immunized mothers acquire passive immunity that protects them from neonatal tetanus. Recovery from tetanus may not result in immunity; second attacks can occur and primary immunization is indicated after recovery.

Occurrence

Worldwide. The disease is more common in agricultural regions and in areas where contact with animal excreta is more likely and immunization is inadequate. Parenteral use of drugs by addicts, particularly intramuscular or subcutaneous use, can result in individual cases and occasional circumscribed outbreaks. In 2006, an estimated 290 000 people worldwide died of tetanus, most of them in Asia, Africa and South America. Over 250 000 of these deaths were due to tetanus neonatorum, dealt with in a separate section below. In rural and tropical areas people are especially at risk, and tetanus neonatorum (see below) is common. There is some inconclusive evidence that at high altitude the risk for tetanus could be lower. The disease is sporadic and relatively uncommon in most industrialized countries.


Prevention and Control

1)    Preventive measures:

a)    Educate the public on the necessity for complete immunization with tetanus toxoid, the hazards of puncture wounds and closed injuries that are particularly liable to be complicated by tetanus, and the potential need after injury for active and/or passive prophylaxis.

b)    Universal active immunization with adsorbed tetanus toxoid (TT), which gives durable protection for at least 10 years; after the initial basic series has been completed, single booster doses elicit high levels of immunity. In children under 7, the toxoid is generally administered together with diphtheria toxoid and pertussis vaccine as a triple (DTP or DTaP) antigen, or as double (DT) antigen when contraindications to pertussis vaccine exist. Preparations that include other antigens including Haemophilus influenzae type b conjugate vaccines (DTP-Hib), Hepatitis B vaccine (DTP-HB), and/or inactivated polio vaccine are also available in some countries.

Tetanus and diphtheria (Td) vaccine is used for children older than seven years. For adolescents and adults up to age 64, and where available, combined tetanus, diphtheria and acellular pertussis (Tdap) vaccine can be safely used as a single dose and for boosting as part of wound prophylaxis. In countries with incomplete immunization programs for children, all pregnant women should receive 2 doses of tetanus toxoid in the first pregnancy, with an interval of at least 1 month, and with the second dose at least 2 weeks prior to childbirth, in order to prevent maternal and neonatal tetanus. Booster doses may be necessary to ensure ongoing protection (see below).

Non-adsorbed (“plain ”) tetanus toxoid vaccines, as opposed to alum adjuvant tetanus toxoid preparations, are less immunogenic for primary immunization or booster shots. Minor local reactions following tetanus toxoid injections are relatively frequent; severe local and systemic reactions are infrequent but do occur, particularly after excessive numbers of prior doses have been given.

i)    The schedule recommended for tetanus immunization in childhood is the same as for diphtheri. The schedule recommended in developing countries is at least 3 primary doses IM at 6, 10 and 14 weeks of age; and a DTP booster at 18 months to 4 years.

The following schedules are recommended for use in industrialized countries (some countries may recommend different ages or dosages):

(1)    Recommended immunization schedule for persons aged 0–18 Years:

The first 3 doses are given at 4- to 8-week intervals beginning when the infant is 6 to 8 weeks of age; a fourth dose is given 6–12 months after the third dose. This schedule should not entail restarting immunizations because of delays in administering scheduled doses. A fifth dose is given at 4–6 years, prior to school entry; this dose is not necessary if the fourth dose was given after the fourth birthday. If the pertussis component of DTP is contraindicated, diphtheria and tetanus toxoids for children (DT) should be substituted. A booster dose with an adult formulation, Tdap (or Td if Tdap is unavailable), is recommended at 11–18 years of age.

(2)    Previously unvaccinated persons aged 7 years.

Because adverse reactions may increase with age, a preparation with a reduced concentration of diphtheria toxoid (adult Td) is usually given after the seventh birthday for booster doses.

For a previously unimmunized person, a primary 3-dose series of adsorbed tetanus and diphtheria toxoids (Td) is advised. Two doses are given at 4- to 8-week intervals, and the third dose is given 6 months to 1 year after the second dose. If the person is aged 10 years or older, a dose of Tdap may be substituted for a single Td dose in the series. Limited data from Sweden suggest that the 3-dose Td regimen may not induce protective diphtheria antibody levels in most adults, and additional doses may be needed.

(3)    Active protection should be maintained by administering a dose of Td every 10 years thereafter. A one-time dose of Tdap may be substituted for the next Td dose in persons ages 19–64 years, for added protection against pertussis.

ii)    While tetanus toxoid is recommended for universal use regardless of age, it is especially important for workers in contact with soil, sewage and domestic animals; members of the military forces; policemen and others with greater than usual risk of traumatic injury; adults with diabetes mellitus; older adults who are currently at highest risk for tetanus and tetanus-related mortality; and women of reproductive age and newborns. Vaccine-induced maternal immunity is important in preventing maternal and neonatal tetanus.


iii)    Active protection should be maintained by administering booster doses of Td every 10 years. A dose of Tdap may be substituted for Td.

iv)    For children and adults who are severely immuno-compromised or infected with HIV, tetanus toxoid is indicated in the same schedule and dose as for immunocompetent persons, even though the immune response may be suboptimal.

c)    Prophylaxis in wound management: Tetanus prophylaxis in patients with wounds is based on careful assessment of whether the wound is clean or contaminated, the immunization status of the patient, proper use of tetanus toxoid and/or TIG (see table below), wound cleaning, and—where required—surgical debridement and the proper use of antibiotics.

i)    Those who have been completely immunized and who sustain minor and uncontaminated wounds require a booster dose of toxoid only if more than 10 years have elapsed since the last dose was given. For major and/or contaminated wounds, a single booster injection of tetanus toxoid (preferably as Td or Tdap) should be administered promptly on the day of injury if the patient has not received tetanus toxoid within the preceding 5 years.

ii)    Persons who have not completed a full primary series of tetanus toxoid require a dose of toxoid as soon as possible following the wound, and may require passive immunization with human TIG if the wound is a major one and/or if it is contaminated with soil containing animal excreta. DTP/DTaP, DT or Td, as determined by the age of the patient and previous immunization history, should be used at the time of the wound, and ultimately to complete the primary series.

Passive immunization with at least 250 IU of human-derived TIG IM (or 1 500 to 5 000 IU of antitoxin of animal origin if globulin is not available), regardless of the patient's age, is indicated for patients with other than clean, minor wounds and a history of no, unknown or fewer than 3 previous tetanus toxoid doses. When tetanus toxoid and TIG or antitoxin are given concurrently, separate syringes and separate sites must be used.

When antitoxin of animal origin is given, it is essential to avoid anaphylaxis by first injecting 0.02 ml of a 1:100 dilution in physiologic saline intradermally, with a syringe containing adrenaline on hand. Pretest with a 1:1000 dilution if there has been prior animal serum exposure, together with a similar injection of physiologic saline as a negative control. If after 15–20 minutes there is a wheal with surrounding erythema at least 3 mm larger than the negative control, it is necessary to desensitize the individual.

Antibiotics may theoretically prevent the multiplication of C. tetani in the wound and thus reduce production of toxin, but this does not obviate the need for prompt treatment of the wound together with appropriate immunization.

Summary Guide to Tetanus Prophylaxis in Routine Wound Management
   Clean, minor wounds All other wounds
History of tetanus immunization (doses) Td2 TIG Td2 TIG
Uncertain or < 3 Yes No Yes Yes
3 or more No3 No No4 No
2)    Control of patient, contacts and the immediate environment:

a)    Report to local health authority: Case report required in most countries, Class 2.

b)    Isolation: Not applicable.

c)    Concurrent disinfection: Not applicable.

d)    Quarantine: Not applicable.

e)    Immunization of contacts: Not applicable.

f)    Investigation of contacts and source of infection: Case investigation to determine circumstances of injury.

g)    Specific treatment: TIG IM in doses of 3 000–6 000 IU. If immunoglobulin is not available, tetanus antitoxin (equine origin) in a single large dose should be given IV following appropriate testing for hypersensitivity. Metronidazole, the most appropriate antibiotic in terms of recovery time and case-fatality, should be given for 7–14 days in large doses; this also allows for a reduction in the amount of muscle relaxants and sedatives required. The wound should be debrided widely if possible. Wide debridement of the umbilical stump in neonates is not indicated. Maintain an adequate airway and employ sedation as indicated; muscle relaxant drugs, together with tracheotomy or nasotracheal intubation and mechanically assisted respiration, may be lifesaving. Active immunization should be initiated concurrently with treatment.

3)    Epidemic measures:

In the rare outbreak, search for contaminated street drugs or other common-use injections.

4)    Disaster implications:

Social upheaval (military conflicts, riots) and natural disasters (floods, hurricanes, earthquakes) that cause many traumatic injuries in non-immunized populations will result in an increased need for TIG or tetanus antitoxin and toxoid for injured patients.

5)    International measures:

Up-to-date immunization against tetanus is advised for international travelers.
 

Source: Heymann (Ed.). (2008). Control of Communicable Diseases Manual, 19th edition. Washington, DC: American Public Health Association.
 


Available Vaccines

WHO-Prequalified Tetanus Vaccines

 

Common Disease Taxonomy: