Bordetella pertussis Infection and Respiratory Viral Co-Detection Among Children in Türkiye: A Three-Year Epidemiological Study

Pertussis can be difficult to distinguish from other respiratory infections in children. Describing respiratory viruses detected alongside Bordetella pertussis may inform the interpretation of multiplex test results, although molecular co-detection does not establish that both organisms caused the illness. This retrospective laboratory-based study evaluated B. pertussis positivity and respiratory viral co-detections among children aged 0-17 years whose respiratory specimens were submitted for multiplex testing to a central laboratory in Türkiye between January 2023 and September 2025. Testing was requested by the referring clinical teams; no standardized symptom-based inclusion criteria were applied. Among 2718 children tested, 61 were positive for B. pertussis (2.24%; 95% CI, 1.75-2.87%). Positivity was highest among infants aged <1 year and decreased with increasing age. Third-quarter peaks were observed in 2023 (17/361; 4.7%) and 2024 (4/90; 4.4%). At least one respiratory virus was co-detected in 30 of the 61 positive children (49.2%); rhinovirus/enterovirus and respiratory syncytial virus were the most frequently identified viruses. These findings support continued pertussis surveillance and consideration of B. pertussis when interpreting multiplex respiratory test results. The clinical significance of viral co-detection could not be assessed without patient-level clinical outcome data.