Epidemiology, outcome and control of varicella-zoster infection

Summary Chickenpox is a mild disease in children, but may be life threatening in immunosuppressed patients, neonates and normal adults, particularly smokers in whom the risk of varicella pneumonia is high. Infection during the first 5 months of pregnancy carries a small risk (probably <1%) of congenital varicella syndrome characterised by unilateral limb hypoplasia, dermatomal skin scarring and neurological damage. However, the greatest burden of morbidity attributed to varicella-zoster infection arises from herpes zoster, which affects 1 in 4 adults by the eighth decade of life. The epidemiology of chickenpox appears to be changing with an unexplained upward shift in the age distribution of cases over the last 20 years. This has important consequences for future mortality rates, and the risk of infection in pregnancy and health care workers. The effectiveness of existing prophylactic and therapeutic measures for varicella zoster infection are reviewed and the potential uses of varicella vaccine are discussed in the light of current evidence of its safety and efficacy in normal and high risk groups.