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Chickenpox
Reviewed by the PMC Medical Team · Promise Medical Centre
Overview
Chickenpox is a highly contagious viral infection caused by the varicella-zoster virus, marked by an itchy, blister-like rash that spreads over the body. It is most common in children under 10 but can affect unvaccinated people of any age, with adult cases often being more severe. Outbreaks are still common in Nigerian schools and households due to low vaccination coverage. Most children recover fully within 1–2 weeks, but the disease can be more serious in adults, pregnant women, newborns, and people with weakened immune systems.
Symptoms
Chickenpox typically develops in stages over 5–7 days:
• Fever, tiredness, loss of appetite, and headache (1–2 days before the rash)
• An itchy rash that starts as small red spots, usually first on the chest, back, and face
• Spots progress to fluid-filled blisters, which then burst, dry up, and form scabs
• New spots continue to appear in crops for several days, so all stages (spots, blisters, scabs) may be visible at once
• Widespread itching
When to See a Doctor
Most cases of chickenpox in healthy children can be managed at home with supportive care. See a doctor to confirm the diagnosis, especially if this is the person's first suspected episode, or if the affected person is an adult, pregnant, a newborn, or has a weakened immune system.
Seek urgent medical care if there is:
• High fever that persists beyond 4 days or a fever that returns after settling
• Signs of skin infection: increasing redness, warmth, swelling, or pus around blisters
• Difficulty breathing, persistent cough, or chest pain
• Severe headache, stiff neck, confusion, or difficulty waking
• Repeated vomiting
• Blisters spreading to the eyes
• Unsteady walking or difficulty with coordination
Causes
Chickenpox is caused by the varicella-zoster virus (VZV), a member of the herpesvirus family. It spreads very easily through:
• Airborne respiratory droplets from coughing or sneezing
• Direct contact with fluid from chickenpox blisters
• Contact with contaminated objects, though this is less common
A person is contagious from about 1–2 days before the rash appears until all blisters have crusted over. After infection, the virus remains dormant in the body and can reactivate later in life as shingles (herpes zoster).
Risk Factors
• Not having had chickenpox before and not being vaccinated
• Close contact with an infected person, especially in households, schools, and daycare centres
• Age under 12 (though anyone unvaccinated and non-immune can be infected)
• Weakened immune system (from illness, chemotherapy, or medication), which raises the risk of severe disease
• Pregnancy: increases risk of complications for both mother and baby
Complications
Complications are uncommon in healthy children but can include:
• Bacterial skin infections at sites of scratched blisters
• Pneumonia, particularly in adults, smokers, and pregnant women
• Encephalitis (brain inflammation) — rare but serious
• Dehydration
• Reye's syndrome, associated with aspirin use in children with chickenpox — aspirin should never be given to children with chickenpox
• Congenital varicella syndrome if a mother is infected in early pregnancy
• Severe, disseminated disease in people with weakened immune systems
• Later in life: shingles (reactivation of the dormant virus)
Prevention
• Varicella (chickenpox) vaccination, given in two doses, is the most effective prevention
• Avoid close contact with infected individuals, especially if pregnant, a newborn, or immunocompromised
• Isolate infected individuals until all blisters have crusted over (usually about a week)
• Wash hands frequently
• Avoid sharing personal items such as towels and utensils with an infected person