Varicella (Pediatric)

Definition

Varicella, or chickenpox, is a highly contagious viral infection in children caused by the varicella-zoster virus, characterized by fever, malaise, and a vesicular rash that progresses through macules, papules, vesicles, and crusts.

Epidemiology

• Common in children aged 1–10 years
• Peak incidence in late winter and spring
• Incidence has decreased in countries with routine varicella vaccination
• Highly contagious, spreading via respiratory droplets or direct contact with lesions
• Most children experience mild, self-limited illness

Etiology

• Varicella-zoster virus (VZV), a DNA herpesvirus
• Primary infection leads to varicella; reactivation causes herpes zoster
• Transmission through inhalation of aerosols from respiratory secretions or direct contact with vesicular fluid
• No significant host predisposition in otherwise healthy children
• Immunocompromised children may develop severe disease

Pathophysiology

• Viral entry through respiratory mucosa
• Replication in regional lymph nodes, followed by viremia
• Dissemination to skin and mucous membranes causing characteristic rash
• Immune response leads to vesicle formation and crusting
• Cell-mediated immunity crucial for viral clearance
• Latency established in dorsal root ganglia; reactivation may cause shingles