zoonoses and communicable diseases common to ... - PAHO/WHO

TETANUS 269toxigenic strains of C. tetani by means of their feces, in cultivated as well as uncultivatedareas.Diagnosis: Prior existence of a wound and accompanying symptoms are the basesfor diagnosis. Direct microscopic examination of wound material is useful. Giventhe urgency of diagnosis, the value of culturing C. tetani is doubtful. It is not alwayspossible to isolate the etiologic agent from a wound.Control: In man, given the soil origin of the infection, the only rational means ofcontrol is active immunization with toxoid. Children 2 to 3 months of age shouldreceive three doses of the toxoid in the triple DPT vaccine (diphtheria, pertussis,tetanus) at intervals of one month to six weeks. They should then receive a booster,preferably administered 18 months after the last dose. An initial series of three dosesinduces protective titers of antitoxin for 5 to 13 years in 90% or more of those vaccinated.Booster shots ensure higher titers of the antitoxin and probably conferimmunity throughout a woman’s childbearing years (Halsey and de Quadros, 1983).Periodic boosters of tetanus toxoid every 10 years are recommended, particularly forpopulation groups most at risk. The effectiveness of the toxoid was confirmed duringWorld War II. US soldiers who were vaccinated with three doses of tetanus toxoidexperienced one case of tetanus among 455,803 wounded, while in the unvaccinatedJapanese army, the incidence was 10 cases per 100,000 wounded soldiers.In developing countries, immunization is recommended for pregnant mothers toprevent tetanus mortality in newborns. The effectiveness of prenatal immunizationwith tetanus toxoid (anatoxin) has been demonstrated. Primary immunization consistsof administering two doses, one at the start of pregnancy and another onemonth later, but not beyond three weeks before birth. If a pregnant woman hasalready been immunized, she only needs a booster and probably has enough antibodiesto protect the children she bears over the next five years (Stanfield andGalazka, 1984).Passive immunization with antitoxin should be reserved for persons with no previousactive immunization who must undergo surgical operations, as well as forwomen after abortion or birth and for their newborn children in high-risk areas. Theuse of human antitoxin serum is preferable, but if unavailable, horse or bovinehyperimmune serum can be used after the patient is tested for a possible allergicreaction to the serum.Wounds should be cleaned and debrided. Persons who have previously receivedbasic toxoid treatment should be given a booster if the wound is small and more than10 years have passed since the last dose. If the patient has a large, contaminatedwound, a booster toxoid should be given if he was not vaccinated in the last fiveyears. Persons who did not receive a full primary series of tetanus toxoid shouldreceive a dose of toxoid and may require an injection of human tetanusimmunoglobulin, if it is a major wound and/or is contaminated (Benenson, 1990).Control procedures in animals are similar. Horses in particular should be vaccinatedwith toxoid; two doses given one to two months apart are sufficient. If thehorse suffers from a potentially dangerous wound, another toxoid injection shouldbe given. If the animal has not received toxoid previously, 2,000 to 3,000 IU of antitoxinshould be given. At the same time, one dose of toxoid should be given andrepeated one month later. The antitoxin confers passive immunity for approximatelytwo weeks. Colts are given toxoid at 2 months of age and mares are given toxoid in