High incidence of Pertussis among schoolchildren with prolonged cough in Turkey.

Older children, adolescents and adults with prolonged cough should be screened for pertussis, because they can be a major source of transmission for infants who are not yet fully immunized. This study aimed to estimate the incidence of pertussis among schoolchildren of 6-14 years old with prolonged cough attending two government primary schools in central Ankara. A questionnaire and an informed consent form were sent to the parents of 1,859 schoolchildren. The former comprised questions regarding sociodemographics, and the presence and duration of cough. Parents of 1,698 (91.3%) schoolchildren returned the questionnaire. Three hundred and eighty three (22.6%) of the schoolchildren had cough for more than two weeks, and 307 (80.2%) of them, whose parents gave consent, were included in the study. Their blood samples were collected twice, with a two-week interval. Anti-pertussis toxin IgG levels were measured by enzyme-linked immunosorbent assay (ELISA). Fifty-one children (16.6%) had evidence of recent pertussis infection documented by either a titer > or = 100 ELISA Unit (EU)/ml in one of two serum samples or seroconversion in paired sera. None of the schoolchildren who had attended health care facilities for cough had been diagnosed as pertussis by a physician. In conclusion, pertussis is evident among older children and adolescents in Turkey, and in order to control the disease, priority should be given to strengthen primary immunization services along with the implementation of booster vaccinations beyond childhood.