Epidemiology of hospital admissions for chickenpox in children: an Italian multicentre study in the pre-vaccine era.

Aim: To describe the chickenpox complications in children in Italy.

Methods: Hospital discharge data from 1 January 2002 to 15 June 2006 were queried for patients less than 18 years of age in three Italian paediatric university hospitals.

Results: During the study period, 349 children (189 males, 160 females) were admitted. Thirteen out of 349 (3.7%) of them had serious underlying diseases. Two hundred and sixty-one (74.8%) children (median age: 41 months, range: 6 days -to 200 months) had complicated chickenpox. Among complications, neurological disorders were the most common (100/261 = 38.3%), followed by skin and soft tissue infections (63/261 = 24.1%), lower respiratory tract infections (57/261 = 21.8%) and haematological disorders (24/261 = 9.2%). Children with neurological complications were significantly older and had a longer hospital stay than those with other complications. Three children with encephalitis and cerebellitis had developed long-term sequelae by the 6-month follow-up. The mortality rate was 0.4% (1/261 children with complicated chickenpox).

Conclusion: Chickenpox is a disease that can provoke serious complications and long hospital stays, even in healthy children. Our findings may be useful as background to evaluate the impact of a tetravalent measles-mumps-rubella-varicella vaccine (MMRV) which is going to be introduced in Italy.