Differential Diagnosis for a 6-month-old with ILI Symptoms

• Single most likely diagnosis:
  • Bronchiolitis: This is the most likely diagnosis given the age of the patient and the symptoms of fever, cough, runny nose, shortness of breath (SOB), and wheezing, which are typical for bronchiolitis, especially in infants under 2 years old. The need to be upright to sleep and increased work of breathing (WOB) with belly breathing also support this diagnosis.
• Other Likely diagnoses:
  • Viral pneumonia: The symptoms of fever, cough, and SOB could also suggest viral pneumonia, which is a common cause of respiratory illness in infants.
  • Asthma: Although less common in infants, asthma could be considered, especially with the presence of wheezing. However, a diagnosis of asthma typically requires more episodes of wheezing and responsiveness to bronchodilators.
  • Upper respiratory tract infection (URTI): Given the symptoms of runny nose, cough, and congestion, a URTI is possible, but the presence of SOB and wheezing suggests a lower respiratory tract involvement.
• Do Not Miss diagnoses:
  • Bacterial pneumonia: Although less likely than viral pneumonia, bacterial pneumonia is a serious condition that requires prompt antibiotic treatment. The presence of high fever, SOB, and increased WOB warrants consideration of this diagnosis.
  • Pertussis (whooping cough): Given the cough and respiratory distress, pertussis should be considered, especially if the infant is not up to date on vaccinations or if there's an outbreak in the community.
  • Congenital heart disease: Infants with undiagnosed congenital heart disease can present with respiratory symptoms due to heart failure. Although less likely, this is a critical diagnosis not to miss.
• Rare diagnoses:
  • Foreign body aspiration: This could cause sudden onset of respiratory symptoms, including wheezing and cough, but is less likely given the gradual onset of symptoms.
  • Cystic fibrosis: A rare genetic disorder that can cause respiratory symptoms, but typically presents with more chronic symptoms and other systemic signs.
  • Pulmonary vascular malformations: Rare conditions that could cause respiratory distress, but are less likely and would typically have other associated symptoms or findings.