[Persistent cough caused by Bordetella pertussis. Study of 6 cases].

BACKGROUND

Pertussis is currently an infrequent illness in Spain, since DTP vaccine was introduced. Immunity acquired after immunization is, nevertheless, lower than immunity acquired after the clinical disease, and decreases steadily. After the adolescence, serum levels of antibodies against B. pertussis may not be enough, leading to atypical infections in other wise immunized patients.

METHODS

We inoculated, during 6 months, nasal swabs of patients with symptoms of pertussis and of patients with persistent cough on blood agar, MacConkey agar, chocolate agar, charcoal agar and Bordet Gengou agar.

RESULTS

We isolated B. pertussis from 6 patients. Five of them were children between 8 and 14 years old, correctly immunized, whose only symptomatology was persistent cough. The only patient incorrectly immunized showed a clinical picture of pertussis. All the patient evolved favorably with erythromycin.

CONCLUSIONS

Immunization with DTP drastically reduces the incidence of serious illness but, after some years, do not protect enough against the appearance of milder, atypical pertussis. These data obligate to take into account the possibility of pertussis infection when persistent cough is observed, in absence of any other factors that can justify it.