Influenza (Pediatric)

Definition

Influenza in children is an acute viral respiratory infection caused by influenza viruses (A, B, or C), characterized by fever, cough, myalgia, and respiratory symptoms, often with seasonal epidemics.

Epidemiology

• Common in children, especially under 5 years of age
• Seasonal outbreaks in winter and early spring in temperate climates
• Higher incidence in children attending daycare or school
• Influenza A is more common and associated with pandemics, Influenza B causes milder epidemics
• Annual vaccination reduces incidence and severity

Etiology

• Influenza virus types A, B, and rarely C
• Transmission via respiratory droplets and direct contact
• Children with chronic illnesses or immunodeficiency at higher risk
• Coinfections with other respiratory viruses may occur
• Poor hand hygiene and crowded settings increase transmission
• Antigenic drift and shift lead to recurrent seasonal infections

Pathophysiology

• Virus infects respiratory epithelial cells causing cell death and inflammation
• Immune response leads to fever, malaise, myalgia, and cytokine-mediated symptoms
• Upper and lower respiratory tract involvement can cause rhinitis, pharyngitis, and bronchitis
• In severe cases, viral pneumonia may develop
• Secondary bacterial infection can complicate disease course
• Systemic effects include dehydration, myositis, and rarely neurologic complications