[Bordetella pertussis in adolescent students in Mexico City].

Objective: To estimate seroprevalence of Bordetella pertussis in students and their community.

Methods: A total of 12,273 adolescent students aged 12 to 15 years from 14 public high schools in Mexico City were studied from September 2002 to March 2003. Nasopharyngeal samples were collected from those adolescents with whooping cough for more than 14 days. Infection was confirmed using polymerase chain reaction (PCR). All students, school staff and family exposed to PCR-confirmed cases were tested.

Results: Whooping cough rate was 5 to 1,000 students. Of those students (61) who were identified with whooping cough for more than 14 days, 20 (32.8%) were positive to Bordetella pertussis. Of 152 people exposed (contacts) to these cases, 16 (10.6%) were positive and only eight (50%) had whooping cough. One of these exposed (contacts) was the principal of a school that had more than 60% positive cases (12/20) and who was also a teacher of 10 infected students. Of 29 family members tested, eight (27.6%) were positive and from three different families.

Conclusions: The study results show a similar rate of whooping cough in adolescents as seen in other countries. Since persistent cough is not always clinically seen in all infected individuals, there may be asymptomatic cases of Bordetella infection.