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Efficacy of tetanus test

The tetanus test I took caused me significant difficulty because it was not meant to diagnose tetanus, nevertheless it was treated as if it was. My experience led me to the following:

Tetanus information from Canada.

Tetanus is an acute and often fatal disease caused by an extremely potent neurotoxin produced by Clostridium tetani, which is found in soil. Tetanus occurs sporadically worldwide but it is uncommon in Canada and other developed countries, mainly because of immunization and hygienic precautions taken in the management of wounds and surgical procedures. Neonatal tetanus is a particular risk for infants born to unimmunized mothers under unhygienic conditions; it is associated with a high mortality rate and is a significant cause of neonatal deaths in some developing countries.

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The case-fatality rate for tetanus ranges from 20% to 90%, and is highest in infants and the elderly.Canadian data for tetanus indicate that the disease has decreased significantly with immunization. During the 1920s and 1930s, 40 to 50 deaths from tetanus were reported annually. With the introduction of tetanus toxoid in Canada in 1940, mortality rapidly declined; only five deaths from tetanus have been reported since 1980.

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Immunization against tetanus is highly effective and provides long-lasting immunity. Primary immunization against tetanus is recommended for all children in Canada and booster doses are recommended for adults at 10-year intervals. Unless previous immunization (i.e. primary and booster within appropriate intervals) can be documented, tetanus toxoid and/or tetanus immune globulin should be used in the management of wounds likely to be contaminated with C. tetani.

1998 Update:  Three cases of tetanus were reported in 1997 and two in 1998. In 1997, two clinical cases and one laboratory confirmed case were reported from Ontario, Nova Scotia and Alberta, respectively.

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The first clinical case was a 50-year-old male who injured his foot stepping on bamboo. He recalled vaccination as a youth, but was unable to specify a date. The second clinical case was in an 80-year-old male from Nova Scotia. He was cutting alders and poked himself in the leg with part of the tree. His vaccination status is unknown.

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The laboratory-confirmed case was a 10-year-old boy with a history of stepping on a nail eight days before admission to hospital. He had a history of three doses of diptheria, pertussis and tetanus (DPT) vaccine as an infant (two, five and nine months of age). Vaccination was discontinued after the third dose due to adverse reaction consisting of fever and generalized rash.Two tetanus cases were reported in Ontario in 1998. One was clinically diagnosed in a 37-year-old male lumberjack wounded on the job. The other was laboratory-confirmed in a 67-year-old male farmer who cut his leg on a sharp board. Prior vaccine receipt was unknown for both of these cases.All cases recovered following treatment.

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Tetanus ToxoidTetanus toxoid is prepared by detoxification of tetanus toxin with formalin. The toxoid is combined with aluminum salts, generally aluminum phosphate, in an adsorbed form.

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Tetanus toxoid is available alone or in various combinations with diphtheria toxoid, pertussis, inactivated poliomyelitis and
Haemophilus influenzae vaccines.

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All preparations contain comparable amounts of tetanus toxoid. The preparations contain either thimerosal or 2-phenoxyethanol with or without formaldehyde, as preservatives.

Preparations that also contain inactivated polio vaccine may contain trace amounts of polymyxin B and neomycin from the cell growth medium.  

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Efficacy and Immunogenicity 

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Tests for measuring the immune response to tetanus toxoid include the serum toxin neutralization bioassay performed in mice and serologic tests, which include enzyme immuno assays (EIA). Because the bioassay is expensive and time-consuming, the EIA is more widely used.

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Protective EIA antibody levels have been variously defined as greater than 0.10-0.15 IU/mL in serosureys; controversy exists regarding the accepted cut-off level.

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Correlation of serologic test results with the toxin bioassay is useful, as the latter assesses actual neutralization in vivo.

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Protective antitoxin levels occur in virtually all healthy infants and children who receive primary immunization. The immune response in premature infants is comparable to that of term infants of the same chronologic age. A double-blind, randomized controlled trial in rural South America demonstrated that two or three doses of tetanus toxoid administered to previously unvaccinated women of childbearing age protected their infants. Efficacy in standard pre-exposure and post-wound booster immunization regimens among adults has not been assessed in randomized trials, but was demonstrated by observational studies during World War II.Most children who are perinatally infected with HIV develop adequate antitoxin antibody responses following immunization with vaccines containing tetanus toxoid.

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The antibody response to boosters given to adults with HIV or other humoral immune deficiencies is suboptimal. Tetanus immunity is lost in approximately half of patients undergoing chemotherapy for lymphoma or leukemia.

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Patients undergoing bone marrow or stem cell transplantation should be re-immunized with two doses, 12 and 24 months after the procedure.

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Very rare cases of tetanus have been reported despite full immunization and the presence of toxin-neutralizing antibody. These cases may present with a clinical spectrum ranging from mild or localized to severe disease. Explanatory theories include the “overwhelming” of host defenses by large quantities of toxin, selective suppression of the immune response or antigenic differences between toxin and toxoid.  

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Recommended Usage

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It is recommended that all Canadians receive a primary immunizing course of tetanus toxoid in childhood, followed by routine booster doses every 10 years. Adults who have not previously received a primary tetanus toxoid series require three doses as part of an adult primary immunization regimen (see Schedule and Dosage in the Guide. Active immunization against tetanus should be undertaken for patients who have recovered from this disease, because infection does not confer protective immunity.

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Schedule and Dosage

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The dose of the various forms of tetanus toxoid licensed in Canada is 0.5 mL. For children < 7 years of age, tetanus toxoid is most commonly used in combination with diphtheria toxoid, acellular pertussis, inactivated polio and H. influenzae type b antigens. For individuals >= 7 years of age, use of an adult-type preparation is recommended e.g. Td, Td-Polio or dTap.

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For children < 7 years of age, the primary immunizing series of adsorbed tetanus toxoid in Canada consists of a dose at 2, 4 and 6 months of age, plus a fourth dose at 18 months. If the fourth primary dose was given before the fourth birthday, a booster dose is also given at 4 to 6 years of age (school entry). Immunization schedules for children not vaccinated in early infancy are shown in Tables 2 and 3 in Part 2: A. Recommended Immunization Schedules for Infants and Children. In adults requiring a primary immunization series, the first two doses of toxoid (preferably given as Td) should be given 4 to 8 weeks apart and the third 6 to 12 months later.

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Route of Administration

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Tetanus toxoid is administered intramuscularly.

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Booster Doses and Re-immunization

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To maintain immunity to tetanus after completion of primary immunization, booster doses administered as Td are recommended at 10-year intervals. More frequent boosters may lead to severe local and systemic reactions. Some experts have suggested that booster doses may be given less frequently, because tetanus cases are uncommon in people who received a primary immunization series but have not received subsequent boosters every 10 years. On the basis of this observation, it has been suggested that immunization status should be reviewed at least once during adult life, e.g., at 50 years of age, and a dose of Td given to everyone who has not had one within the previous 10 years. However NACI’s continued recommendation for tetanus boosters every 10 years is based on concern regarding the decline of antibody levels with age and potential failure of single booster doses to produce protective levels in older individuals.

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For individuals planning to travel to developing countries where safe tetanus toxoid administration may not be available if required, it may be prudent to offer an early tetanus booster prior to travel if more than 5 years have elapsed since the last dose.

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Storage Requirements   

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Toxoid preparations should be stored in the refrigerator, at a temperature between 2o C and 8o C. They should not be frozen, and any that have been frozen should not be used.

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Post-exposure Prevention of Tetanus in the Context of Wound Management  

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The Table below summarizes the recommended use of immunizing agents in wound management. It is important to ascertain the number of doses of toxoid previously given and the interval since the last dose. When a tetanus booster dose is required, the combined preparation of tetanus and diphtheria toxoid formulated for adults (Td) is preferred. Appropriate cleansing and debridement of wounds is imperative, and use of antibiotics may be considered.

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Some individuals with humoral immune deficiency, including those with HIV infection, may not respond adequately to tetanus toxoid. Therefore, tetanus immune globulin (TIG) should be used in addition to tetanus toxoid if a wound occurs that is not clean, regardless of the time elapsed since the last booster.

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Simultaneous Administration with Other Vaccines  

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Tetanus toxoid preparations may be given concurrently with other vaccines in circumstances in which this would be advantageous.

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Adverse Reactions   

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Adverse reactions to primary immunization with tetanus toxoid are rare, especially in children. Their incidence in adults increases with age. Following booster doses, local erythema and swelling are not uncommon. Severe local reactions occur rarely and may be associated with high levels of circulating antitoxin resulting from over-immunization. Lymphadenopathy may occasionally occur. Fever has been infrequently reported and usually occurs in cases showing a marked local reaction. Systemic reactions, such as generalized urticaria, anaphylaxis, serum sickness and brachial plexus neuropathy, have rarely been reported. Attribution of adverse reactions to tetanus toxoid may be confounded if other antigens are present in the preparation.
Trismus associated with tetanus toxoid immunization has rarely been reported. Outcomes have been favourable. The pathogenesis is unexplained.

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Contraindications and Precautions

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It is recommended that tetanus toxoid not be given routinely to a patient who has received a booster dose in the preceding 5 years.

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Tetanus toxoid should not be given if a severe systemic reaction, including severe hypersensitivity or a neurologic event, followed a previous dose.

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People who experience a major local reaction or high fever following a dose of tetanus toxoid should not be given another dose for at least 10 years. In those who have experienced severe local reactions or fever after tetanus toxoid, plain toxoid may be considered for subsequent booster doses, since it is reported to cause fewer reactions than adsorbed toxoid. When a contraindication to tetanus toxoid exists and a patient sustains a major or unclean wound, tetanus immune globulin should be given.

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Before a combined vaccine is given, it is most important to ensure that there are no contraindications to the administration of any of the components.

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There is no evidence that tetanus toxoid is teratogenic, but it is prudent to wait until the second trimester of pregnancy to administer a routinely required dose, to minimize concern about the theoretic possibility of a relation with any observed birth defect. In the event of a tetanus-prone wound during pregnancy the recommendations in the table should be followed. Neonatal tetanus may occur in infants born to unimmunized mothers under unhygienic conditions.

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Selected References  

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Bardenheier B, Prevots DR, Khetsuriani N et al. Tetanus surveillance – United States, 1995-1997. MMWR 1998;47(SS-2):1-13.

Fiorillo L, Robinson JL. Localized tetanus in a child. Ann Emerg Med 1999;33:460-63.

Katz K, Walmsley S. Postoperative tetanus: a case report. Can Med Assoc J 2000;163(5):571-73.

Mayand C, Loupi E, Charara O et al. Trismus et vaccination antitétanique. Arch Pediatr 1999;6(7):
752-54.

Shimoni Z, Dobrousin A, Cohen J et al. Tetanus in an immunised patient. BMJ 1999;319:1049.

Wassilak SGF, Orenstein WA, Sutter RW. Tetanus toxoid. In: Plotkin SA, Orenstein WA, eds. Vaccines. 3rd edition. Philadelphia: W.B. Saunders 1999:441-74.

Yuan L, Lau W, Thipphawong J et al. Diphtheria and tetanus immunity among blood donors in Toronto. Can Med Assoc J 1997;156:985-90.

[Vaccine Preventable Diseases]
[Division of Immunization and Respiratory Diseases]

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Last Updated: 2002-10-23

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