Pertussis in a vaccinated 12-year-old girl.

Pertussis, though uncommon in people older than 9 years, does occur (in girls and women primarily) and should be considered in the differential diagnosis of persistent cough. Earlier this year in British Columbia a 12-year-old girl contracted the disease, even though she had been fully vaccinated against it at the appropriate ages. The source of her infection was unknown. The clinical picture was classic except that the girl experienced intense headaches, lasting up to an hour, after the episodes of paroxysmal coughing. Canadian physicians and public health practitioners should encourage vaccination against pertussis.