Differential Diagnosis for a 5-Week-Old Boy with Progressive Cough
- Single Most Likely Diagnosis
- A) Bordetella pertussis: The clinical presentation of a 2-week history of progressive cough, coughing until struggling to breathe, and vomiting without fever, especially in a young infant, is highly suggestive of pertussis (whooping cough). The fact that the patient's father also has a cough supports this diagnosis, as pertussis is highly contagious.
- Other Likely Diagnoses
- D) Respiratory syncytial virus (RSV): Although RSV typically presents with symptoms of a lower respiratory tract infection such as bronchiolitis, it can cause cough and respiratory distress in infants. However, the lack of fever and the specific pattern of coughing until struggling to breathe makes it less likely than pertussis.
- B) Influenza virus: Influenza can cause cough and respiratory symptoms in infants, but it usually presents with fever, which is absent in this case.
- Do Not Miss Diagnoses
- E) Streptococcus pneumoniae: Although less likely given the clinical presentation and the lack of abnormalities on the chest x-ray, bacterial pneumonia (e.g., caused by Streptococcus pneumoniae) is a serious condition that must be considered, especially in infants, due to the potential for severe consequences if missed.
- Rare Diagnoses
- C) Mycoplasma pneumoniae: This organism typically causes mild infections in older children and adults, and it would be unusual for it to cause significant symptoms in a 5-week-old infant. However, it cannot be entirely ruled out without further testing.
- Other rare causes of cough in infants, such as congenital anomalies or cystic fibrosis, are not directly suggested by the clinical presentation but could be considered if initial diagnoses are ruled out and symptoms persist or worsen.