A patient presents with cough, low-grade fever, malaise, and no hypoxia. The most likely diagnosis is:

• A. Bacterial pneumonia
• B. Viral upper respiratory infection
• C. Asthma with bronchitis
• D. Allergic rhinitis

Answer: (B)

Recognizing the pattern of an acute cough with a low-grade fever and malaise while oxygen levels remain normal points toward a viral upper respiratory infection. Viral URIs commonly cause cough with mild fever and malaise, and they typically do not produce hypoxia or focal lung findings. In contrast, bacterial pneumonia usually presents with higher fever, productive cough, chest pain, tachypnea, hypoxia, and exam or imaging findings of consolidation. Asthma with bronchitis could involve cough and sometimes wheeze, but fever is not a consistent feature and systemic malaise is less prominent. Allergic rhinitis presents with nasal symptoms and itching, not fever or hypoxia.