Background

In the United States, immunization against pertussis, tetanus and diphtheria became widespread in the late 1940s and resulted in a decrease in the incidence of morbidity and mortality from these diseases. Diphtheria and Tetanus Toxoids and Acellular Pertussis Vaccine Adsorbed (DTaP) vaccines were first available for use in infants in the US in 1996 and have been routinely recommended for all doses of the vaccination series for infants and children <7 years of age since 1997. ⁽⁴⁾

Tetanus

Tetanus is an acute and often fatal disease caused by an extremely potent neurotoxin produced by C tetani. The toxin causes neuromuscular dysfunction, with rigidity and spasms of skeletal muscles. The muscle spasms usually involve the jaw (lockjaw) and neck and then become generalized.

Spores of C tetani are ubiquitous. Serological tests indicate that naturally acquired immunity to tetanus toxin does not occur in the US. Thus, universal primary immunization, with subsequent maintenance of adequate antitoxin levels by means of appropriately timed boosters, is necessary to protect all age groups. Following immunization, protection generally persists for at least 10 years. ⁽⁵⁾

Diphtheria

C diphtheriae may cause both localized and generalized disease. The systemic intoxication is caused by diphtheria exotoxin, an extracellular protein metabolite of toxigenic strains of C diphtheriae. Both toxigenic and nontoxigenic strains of C diphtheriae can cause disease, but only strains that produce toxin can cause severe manifestations such as myocarditis and neuritis. Toxigenic strains are more often associated with severe or fatal respiratory infections than with cutaneous infections.

Complete immunization significantly reduces the risk of developing diphtheria and immunized persons who develop disease have milder illness.

Immunization with diphtheria toxoid does not, however, eliminate carriage of C diphtheriae in the pharynx, nose, or on the skin. Following immunization, protection lasts at least 10 years. ⁽⁵⁾

Pertussis

Pertussis (whooping cough) is a disease of the respiratory tract, most often caused by B pertussis. This gram-negative coccobacillus produces a variety of biologically active components, though their role in pathogenesis is not clearly defined. Widespread use of pertussis vaccines among infants and children younger than 7 years of age led to a gradual decline in reported cases from the late 1940s through the 1970s. From 1980 through 2003, the number of pertussis cases reported annually in the US has increased, with adolescents and adults accounting for a substantial percentage of the reported cases. ^{(6) (7)}

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