Differential Diagnosis for Pneumonia in a 17-Month-Old Unvaccinated Child
Single Most Likely Diagnosis
- Respiratory Syncytial Virus (RSV) pneumonia: This is the most common cause of pneumonia in children under 2 years old, especially in those who are unvaccinated. The child's age and lack of vaccination make RSV a highly likely culprit.
Other Likely Diagnoses
- Influenza pneumonia: Given the child's history of seasonal allergies and reactive airway disease, influenza is a plausible cause, especially during flu season.
- Streptococcus pneumoniae pneumonia: Although less common in this age group, S. pneumoniae is a significant pathogen in unvaccinated children, and the child's reactive airway disease may increase susceptibility.
- Haemophilus influenzae type b (Hib) pneumonia: Another vaccine-preventable disease, Hib is a possible cause in unvaccinated children, especially those with underlying respiratory conditions.
Do Not Miss Diagnoses
- Pertussis (Bordetella pertussis) pneumonia: Although less common, pertussis can cause severe pneumonia in young children, and its diagnosis is crucial due to the risk of complications and transmission to others.
- Mycoplasma pneumoniae pneumonia: Typically seen in older children, M. pneumoniae can still cause pneumonia in younger children, especially those with underlying respiratory conditions, and is essential to consider due to its potential for severe outcomes.
- Staphylococcus aureus pneumonia: This bacterium can cause severe, necrotizing pneumonia, especially in children with underlying conditions like reactive airway disease, making it a critical diagnosis not to miss.
Rare Diagnoses
- Adenovirus pneumonia: While adenovirus can cause respiratory infections, it is less common than other viruses like RSV in this age group.
- Cytomegalovirus (CMV) pneumonia: Typically seen in immunocompromised individuals, CMV pneumonia is rare in otherwise healthy children but could be considered in those with severe disease or underlying immunodeficiency.
- Pneumocystis jirovecii pneumonia: Usually associated with immunocompromised states, P. jirovecii pneumonia is rare in healthy children but should be considered in those with severe pneumonia and no clear alternative diagnosis.