Chickenpox is caused by the varicella zoster virus (VZV). It causes a highly contagious, generalised vesicular rash. It is common in children. Once a child has had an episode of chickenpox, they develop immunity to the VZV virus and will not be affected again.
Chickenpox is characterised by widespread, erythematous, raised, vesicular (fluid filled), blistering lesions. The rash usually starts on the trunk or face and spreads outwards affecting the whole body over 2 – 5 days. Eventually the lesions scab over, at which point they stop being contagious.
- Fever is often the first symptom
- General fatigue and malaise
Chickenpox is highly contagious and spread through direct contact with the lesions or through infected droplets from a cough or sneeze. Patients become symptomatic 10 days to 3 weeks after exposure. The stop being contagious after all the lesions have crusted over.
- Bacterial superinfection
- Conjunctival lesions
- Encephalitis (presenting as ataxia)
After the infection the virus can lie dormant in the sensory dorsal root ganglion cells and cranial nerves reactivate later in life as shingles or Ramsay Hunt syndrome.
Antenatal and Neonatal Chickenpox
Pregnant women that are known to be immune to chickenpox are not at risk when in contact with chickenpox. When they are not immune, varicella zoster immunoglobulins can be given to protect them against the virus after exposure.
Chickenpox in pregnancy, before 28 weeks gestation, can cause developmental problems in the fetus in a small portion of patients. This is known as congenital varicella syndrome.
Chickenpox in the mother around the time of delivery can lead to life threatening neonatal infection and is treated with varicella zoster immunoglobulins and aciclovir.
Chickenpox is usually a mild self limiting condition that does not require treatment in otherwise healthy children.
Aciclovir may be considered in immunocompromised patients, adults and adolescents over 14 years presenting within 24 hours, neonates or those at risk of complications.
Complications such as encephalitis require admission for inpatient management.
Symptoms of itching can be treated with calamine lotion and chlorphenamine (antihistamine).
Patients should be kept off school and avoid pregnant women and immunocompromised patients until all the lesions are dry and crusted over. This is usually around 5 days after the rash appears.
Last updated January 2020