Varicella (chickenpox), one of the childhood exanthems, is caused by the human alpha herpes virus, varicella zoster. Varicella-zoster virus (VZV) is an exclusively human virus.

• Normally presents in childhood and is self limiting
• Adults, pregnant women, immunosuppressed patients, and neonates are at high risk of complications from varicella, including pneumonia, neurological sequelae, hepatitis, secondary bacterial infection, and death.

Pathophysiology

• VZV is spread by direct contact with vesicle fluid from skin lesions or respiratory droplets from nasopharyngeal secretions.
• The incubation period is about 14 days (range 9 to 21 days).
• Patients are considered infective 48 hours before rash onset until the typical skin lesions have fully crusted over.
• The immune system is unable to completely clear the virus, which remains dormant within the dorsal root ganglia of nerves. As we age, or through immunosuppression, the virus may replicate and reemerge as shingles.

Risk factors:

• Exposure to varicella
• Age 1-9 years
• Unimmunised status
• Occupational exposure

PC

*Presence of risk factors

• Fever
  • Consider secondary bacterial infection in patients with persistent fever
• Vesicular pleomorphic rash
  • Usually proceded by grotty/snotty like prodome
  • First appears centrally and then spreads to extremities
  • First macules, quickly develop into fluid filled vesicles, and then they pop and crusting