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Tony Walls, Elizabeth Wilson
In New Zealand it is generally accepted that varicella is a universal childhood illness, a necessary evil that is troublesome but usually benign. Those of us who work in hospital paediatrics have a different perspective on this highly transmissible viral infection. Severe morbidity from suppurative or neurological complications of varicella, necrotising fasciitis, or even death of immune-compromised children, is as unacceptable as tetanus or other vaccine-preventable disease when very effective varicella vaccines have been available for over a decade.
In this issue of the Journal, de Almeida et al report a case of life-threatening pericardial tamponade in a young child as a complication of primary varicella infection (http://www.nzma.org.nz/journal/123-1326/4436). She developed a secondary infection with Staphylococcus aureus and required pericardectomy and a lengthy course of intravenous antibiotics. It is likely that this illness could have been prevented had she received varicella vaccination.
Varicella is not a notifiable disease in New Zealand, but its annual incidence should approximate the birth cohort,1 currently 60,000 per year, with almost 90% of cases occurring in childhood. Approximately one to two cases per year result in long-term disability or death, and 0.5-1 cases result in severe congenital varicella syndrome.2
In temperate climates the rates of hospitalisation with varicella are highest in children 0-4 years, more than 20 times that for those >15 years of age, although the risk of severe disease, usually with varicella pneumonitis, increases with age. New Zealand hospital admission numbers have increased from approximately 50 per annum in 19701 to approximately 300 in 2002.3 Most of these hospitalisations occur in people without underlying medical conditions, with only 4% of hospitalisations involving people with an underlying immune deficiency.
It is likely that these numbers are an underestimate: Some complications such as acute demyelinating encephalomyelitis (ADEM) or stroke occur after the rash has disappeared, and the risk of skin and soft tissue or invasive infections due to Group A Streptococcus and Staphylococcus aureus persists for several weeks after chicken pox, meaning some cases may not be...