Chickenpox (Varicella)
Definition
Highly contagious infection caused by the varicella-zoster virus
Characterised by pruritic vesicular lesions, mild to moderate fever, and malaise
More severe in adults, pregnant women, neonates, and immunocompromised individuals
Transmission and Infectious Period
Spread by respiratory droplets or direct contact with vesicular fluid
Infectious from 2 days before rash until all lesions have crusted
Advise isolation at home until blisters have fully dried
Oral Acyclovir
Indicated for children with eczema at any stage of the rash
Indicated for adults if started ≤36 hours after rash onset
Indicated for pregnant women if started ≤72 hours after rash onset
Reduces disease severity and risk of complications when initiated early
Intravenous Acyclovir
Indicated for individuals needing IV immunoglobulin who are symptomatic
Indicated for chickenpox complications such as pneumonia or encephalitis
Consider in immunocompromised patients at risk of severe or rapidly progressing infection
Immunoglobulin (IVIG)
Ideally given ≤4 days post-exposure (up to 10 days)
Indicated for immunocompromised individuals, pregnant women, and neonates under 1 month (especially preterm)
Reduces severity or prevents disease when administered promptly after exposure
Vaccination Post-Exposure
Recommended within 3–5 days of exposure
For unimmunised individuals older than 12 months
Significant exposure includes household contact, face-to-face contact ≥5 minutes, or sharing a room ≥1 hour
May prevent or attenuate the illness if given early
Complications
Commonly include secondary bacterial skin infections
Severe complications can involve pneumonia, encephalitis, or hepatitis
Pregnant women are at risk of severe maternal illness and neonatal varicella
Notes
Advise individuals to avoid close contact with high-risk groups until crusting
Monitor for signs of respiratory difficulty, neurological changes, or secondary skin infection
Early recognition and treatment are crucial to minimise morbidity and transmission
