Etiology of pertussis syndrome.

One hundred patients with clinical pertussis were studied to determine the etiology of pertussis syndrome. Forty-two (42%) of the patients had either Bordetella pertussis of Bordetella parapertussis isolated from the nasopharynx. In additional 36 (36%) patients, B pertussis was isolated from the nasopharynx of the associated index case or family contact case. Thus, Bordetella was isolated from 78 (78%) of the patients or from their immediate family group. Of the 22 culture-negative patients residing in culture-negative families, 12 had serologic evidence of Bordetella infection and another was from a family group in which two members were seropositive. Therefore, 91 patients (91%) had bacteriologic or serologic evidence of Bordetella infection themselves or within their families. Viral cultures were obtained on 75 of the patients. Adenoviruses were isolated from 33% of those with positive cultures for B pertussis and from 14% of those with negative cultures. In the group without direct or indirect, bacteriologic or serologic evidence of Bordetella infection, the adenoviral isolation rate (13%) was not significantly different from the adenoviral isolation rate (33%) in patients with a positive bacterial culture. These data do not support a role of adenovirus alone in causing pertussis syndrome.