secondary infections such as pneumonia and otitis media. Developmental retardation and bronchiectasis may be permanent sequelae (Mortimer, 1982).
Pertussis responds poorly to treatment with antimicrobial drugs (Mortimer, 1982). Erythromycin and ampicillin, the two most commonly used antibiotics, are effective only if given in the earliest stages, although secondary complications caused by organisms other than Bordetella pertussis usually respond satisfactorily.
In the United States, morbidity and mortality due to pertussis declined rapidly following widespread adoption of the pertussis vaccine in the 1940s, and its official standardization in 1949. By 1967, the crude mortality rate from pertussis in this country had decreased to less than 1 percent of the 1930 rate; between 1970 and 1974, only 52 pertussis deaths occurred in the U.S. (Mortimer, 1982). Epidemiological studies show that the vaccine played an important role in these reductions, although not all of the decline can be attributed to its use (some decline in morbidity and mortality from pertussis was observed in industrialized nations prior to the start of immunization).
Recently, the incidence of pertussis has increased in Sweden, England, and Japan, where use of the vaccine has decreased because of the fear of severe reactions, or because vaccine of low potency has been used (Fulginiti, 1984). Pertussis remains a significant contributor to infant mortality in developing countries.
Although the incidence of pertussis in the U.S. is low, the disease is ubiquitous. In 1983, 2,258 cases (provisional total) were reported to the Centers for Disease Control (CDC) (Centers for Disease Control, 1984). This total probably represents only a fraction of all pertussis infections occurring in the country, however, for the following reasons: cases frequently go unreported or are not recognized; verification of infection by isolation of the organism requires culture methods not used routinely in many diagnostic laboratories; serologic testing is not feasible for routine diagnosis; and infection in immunized or partially immunized children may cause bronchitis, but without the typical whooping.
The current pertussis vaccine is composed of inactivated whole cells of B. pertussis. In the United States it is used exclusively in combination with diphtheria and tetanus toxoids, adsorbed with alum. The efficacy of the DPT vaccine against pertussis following primary immunization is about 90 percent (Broome, 1984; Centers for Disease Control, 1982). About 95 percent of infants and children in the U.S. receive the DPT vaccine according to schedules recommended by the Advisory Committee on Immunization Practices and the American Academy of Pediatrics (1982).
The safety of the current whole cell pertussis vaccine component has been the subject of considerable debate within the medical literature and within the public arena (Fulginiti, 1984). Low grade fever and local tenderness appear frequently after injection. Severe or disturbing untoward reactions, including shock, convulsions, encephalopathy, and persistent high-pitched screaming, are rare complications (Hinman and Koplan, 1984). The rates of these adverse reactions are difficult to determine precisely, at least in part because they often