Review Note

Viral Acute Respiratory Tract Infections

• Acute viral respiratory tract infections include:
  • Upper respiratory tract infections (URTIs): Common cold, sinusitis, pharyngitis, epiglottitis.
  • Lower respiratory tract infections (LRTIs): Bronchitis, bronchiolitis, croup, pneumonia.
    
    
    

• Common Viral Causes:
  • Influenza virus A & B.
  • Parainfluenza viruses.
  • Respiratory syncytial virus (RSV) – commonly causes bronchitis.
  • Adenovirus.
  • Rhinovirus – commonly causes the common cold.
  • Coronaviruses – commonly cause the common cold, also COVID-19 infection.
  • Measles.
• Other Differential Diagnoses:
  • Bacterial causes: S. pneumoniae, H. influenzae, MTB.
  • Fungal causes: Aspergillosis, P. jirovecii.
    
    
    

• Clinical Diagnosis:
  • URTIs: Sore throat, cough, runny nose, nasal congestion, sneezing, headache, low-grade fever, facial pressure.
  • LRTIs: Fever, chills, cough (± sputum), tachypnea, tachycardia, wheezing, rhonchi, rales, chest pain.
• If Pneumonia is Suspected:
  • Chest X-ray: Usually shows interstitial pneumonia in viral etiology.
  • Sputum Sample & Culture.
  • Laboratory Tests: CBC, CRP.
• Testing for Specific Etiology (Indications):
  • Severe infection.
  • During pandemics (e.g., COVID-19) to control spread.
  • Epidemiological purposes.
  • Tests: Nasal, oral, or pharyngeal swab – PCR, ELISA, viral culture.
    
    
    

• General Symptomatic Treatment:
  • Adequate hydration.
  • Rest.
  • Analgesics for pain & fever.
  • Antitussives:
    • Dextromethorphan/codeine for non-productive cough.
    • Acetylcysteine for productive cough.
• Antiviral Therapy (Selected Cases):
  • Oseltamivir for influenza in high-risk patients (should be initiated within 48 hours of symptom onset).
• Severe Cases:
  • Hospitalization may be required, e.g., for viral pneumonia.
    
    
    

• Non-Specific Measures:
  • Good hand hygiene.
  • Covering mouth & nose when sneezing or coughing.
  • Staying home when sick.
  • Avoiding contact with sick individuals.
  • Ensuring good ventilation in public buildings.
• Specific Measures:
  • Vaccines: Influenza, COVID-19, measles.