Pertussis in Infancy: A Case of Delayed Diagnosis.

Bordetella pertussis is a gram-negative bacterium that primarily infects the respiratory tract. We report the case of a 13-month-old male patient who developed pertussis. At the initial clinic presentation, the diagnosis was not immediately considered, as the early manifestations closely mimicked those of a viral upper respiratory infection. As the illness progressed, the classic paroxysmal cough with inspiratory "whoop" became apparent, prompting the correct diagnosis. At that time, a nasopharyngeal swab was obtained, which tested positive for Bordetella pertussis by polymerase chain reaction (PCR). The patient was prescribed a five-day course of azithromycin, and close contacts were given prophylactic treatment.  This case underscores the critical importance of early recognition and timely diagnosis to prevent potentially life-threatening complications. It also highlights the necessity of vaccination awareness. Educating parents and caregivers on the benefits of immunization against vaccine-preventable diseases is essential to safeguard vulnerable individuals and to promote community-wide protection through herd immunity.