Which statement about pneumonia etiologies in children under 5 is most accurate?

• A. Most cases are fungal infections
• B. Most cases are autoimmune processes
• C. Most cases are viral infections
• D. Most cases are parasitic infections

Answer: (C)

In children under five, viral infections are the most common cause of pneumonia. The young immune system and frequent exposure to respiratory viruses mean that pathogens like RSV, influenza, parainfluenza, rhinovirus, and metapneumovirus predominately drive lower respiratory tract infections in this age group. Viral pneumonia often presents with diffuse airway involvement and tends to improve with supportive care, rather than requiring antibiotics aimed at bacteria. While bacterial pneumonia does occur, it is less common in this age group, and when it does present, it’s more likely to show focal signs or lobar consolidation. Fungal, autoimmune, and parasitic causes are rare in otherwise healthy young children, making viral etiology the most accurate choice.