Majority of children recover without any complications but neonates, adults, pregnant women and those who are immunocompromised may have more serious complications (1). Complications include:
Pulmonary involvement:
- between 5 and 14% of adults will have pulmonary involvement
- pneumonia - particularly in adults; also pneumonia caused by the chicken pox virus itself
- the risk is increased in pregnant women, the immunocompromised, those with pre-existing lung disease (not including asthma), and smokers (2)
Central nervous system involvement:
- cerebellar ataxia – usually seen during the recovery period
- encephalitis:
- rarely seen in adults (2)
- classically presenting with ataxia 3 to 4 days after onset of rash, although sometimes up to 8 days, often affecting the cerebellum
- 80% make a full recovery
Secondary bacterial infections:
- bacterial infection of lesions
- common organisms include Staphylococcus aureus or Group A Streptococci
- skin and soft tissue infection, osteomyelitis, septicaemia or toxic shock syndrome may occur (2)
Haemorrhagic complications
- pulmonary and gastrointestinal bleeding
- intra-cerebral haemorrhage
- disseminated intravascular coagulation (2)
In pregnancy:
- considerable maternal morbidity
- congenital varicella syndrome in 10% if infected in first 20 weeks of gestation
Less common complications include
- arthritis, glomerulonephritis, myocarditis, and purpura fulminans (3)
Reference: