Bordetella parapertussis infection in children: epidemiology, clinical symptoms, and molecular characteristics of isolates

Abstract

The clinical trial conducted in Italy to evaluate the efficacy of acellular pertussis vaccines provided an opportunity to estimate the frequency of clinical infections with Bordetella parapertussis and to compare the clinical characteristics of children suffering from Bordetella pertussis illness with those of children with B. parapertussis illness. This study dealt with 76 B. parapertussis infections diagnosed from a population of 15,601 children participating in the follow-up of suspected cases of pertussis. An overall incidence of 2.1 cases of laboratory-confirmed parapertussis per 1,000 person-years was observed. Children affected by B. parapertussis infections showed a less severe clinical picture both in the duration of symptoms and in the percentage of patients affected, even when compared with vaccinated children with pertussis. To characterize the isolated strains, we performed assays for susceptibility to erythromycin and sulfamethoxazole-trimethoprim, and we examined the genomic DNAs by pulsed-field gel electrophoresis. The results showed a high degree of genetic stability among B. parapertussis strains regardless of time of collection and geographical distribution.

FIG. 1

Trend of B. pertussis and B. parapertussis infections in Italy by calendar month (September 1992 to September 1995).

FIG. 2

Mean durations of symptoms in children with B. parapertussis and B. pertussis infections, by vaccine group. Symbols: □, coughing; ▪, spasms; ░⃞, whooping; , vomiting; ▨, apnea; , cyanosis.

FIG. 3

PFGE profiles of B. parapertussis NPAs digested with three different restriction enzymes, as shown. Lane λ, lambda ladder molecular-size markers (New England Biolabs); lanes a, d, and g, B. parapertussis ATCC 9305 DNA; lanes b, e, and h, B. parapertussis DNA with profile indistinguishable from that of B. parapertussis ATCC 9305 (pattern A); lane c, B. parapertussis DNA with profile slightly different (pattern A1) from that of B. parapertussis ATCC 9305 after digestion with XbaI (arrow indicates the presence of a different band, of approximately 250 kb); lanes f and i, B. parapertussis DNA representative of pattern A1 digested by SpeI and DraI, respectively.