[Culture-confirmed whooping cough in a tertiary center over a twelve-year period]

To study the characteristics of patients diagnosed with whooping cough at a tertiary center in Barcelona, Spain.

We performed a retrospective study of patients aged less than 18 years treated for pertussis-like cough or clinically-suspected whooping cough over a 12-year period (1989-2000). Only patients with isolated Bordetella spp. were included. The variables of age, sex, vaccination status, hospitalization, clinical manifestations, severity, and lethality were analyzed.

One hundred sixty-one patients with positive Bordetella spp. culture were identified. Of these, complete information was available in 149 (79 boys and 70 girls) with a median age of 3 months (range: 13 days-17 years); 77.2 % were aged 6 months or less. All the isolated strains corresponded to B. pertussis except three that corresponded to B. parapertussis. Three epidemic cycles (in 1989, 1992 and 2000) were observed during the study period. A total of 72.5 % of cases occurred between May and September. Bordetella spp. was associated with other bacteria in 28.2 % of the patients, viruses in 13.4 % and a bacterium and a virus in 4.7 %. One hundred twenty-one patients required hospitalization, of which 14.9 % were admitted to the intensive care unit. Age was the only factor associated with risk for hospitalization, which was more frequent in younger infants (p < 0.0001). Paroxysmal cough with cyanosis was present in 53.4 % of the patients, leucocytosis with lymphocytosis occurred in 67.5 % and apneas were present in 21.5 %. Chest X-ray revealed atelectasis in 34.1 %. The mean length of hospital stay was 11 days (range: 1-70 days). Three boys aged less than 3 months with malignant pertussis syndrome died (lethality: 2 %). More than half the patients (59.7 %) were not vaccinated (55.4 % for being under the age of 3 months) and only 16 % had received three or more vaccination doses.

Whooping cough continues to be a severe disease in infants, with a high admission rate during the first 6 months of life. New preventive strategies are required to protect infants who have not yet developed full immunity to this infection.