Chickenpox is the primary infection with the varicella-zoster virus (VZV). It is a highly contagious rash illness transmitted by airborne or droplet pathways.
The usual incubation period is 14-16 days (range 10-21 days).
Second cases of varicella have been reported in immunocompetent persons but are rare.
Following chickenpox, VZV establishes latency in sensory nerve ganglia. The virus can reactivate later in life causing herpes zoster (shingles), usually localized to one to three dermatomes. Transmission of VZV to a susceptible person occurs through contact with either a person with varicella or, less commonly, a person with herpes zoster.
Chickenpox is generally a mild disease in children.
Symptoms
A progressive itchy red rash is the primary symptom of chickenpox.
It usually lasts 4-7 days and is characterised by a short (1- to 2-day) or absent prodromal period (low-grade fever, malaise) and by a pruritic rash consisting of crops of macules, papules, vesicles, and eventual crusting, which appear in three or more successive waves.
Serious complications are the exception but can occur. They include secondary bacterial infections of skin lesions, pneumonia, cerebellar ataxia, and encephalitis.
Treatment
Treatment in children with chickenpox is symptomatic (eg. paracetamol for fever).
There is a vaccine available to prevent chickenpox infection.
Because the vaccine is 70%-90% effective, a modified varicella infection, known as breakthrough disease, can occur in some vaccinated persons. Breakthrough disease is almost always mild with rash with fewer than 50 skin lesions, which may be atypical in appearance.
Acyclovir is an option for treatment of some individuals with varicella. Oral Acyclovir is not recommended for postexposure prophylaxis.
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