title: An increasing incidence of chickenpox central nervous system complications in children: what's happening in Tuscany?
abstract: BACKGROUND
  The most frequent noncutaneous site of involvement of chickenpox is the central nervous system (CNS) and complications include cerebellar ataxia, encephalitis, and meningitis.
  
  
  OBJECTIVE
  We have recently observed an unusually high number of children with chickenpox CNS complications in our university children's hospital. A study to evaluate the incidence of these complications over time in children living in Tuscany was carried out.
  
  
  METHODS
  We evaluated all cases of chickenpox and chickenpox complications leading to hospitalization in children aged 1 month-14 years reported to the Tuscany public health centre between 1997 and 2004. The International Classification of Disease Ninth Revision-CM hospital discharge diagnostic codes and medical records were used.
  
  
  RESULTS
  The incidence (95% confidence interval) of CNS complications/1000 chickenpox cases was stable between 1997 and 2001 [1997: 0.80 (0.29-1.74); 1998: 0.73 (0.29-1.50); 1999: 0.67 (0.25-1.46); 2000: 0.56 (0.15-1.44); 2001: 0.59 (0.16-1.50)] but increased significantly (chi(2) for trend: 9.401; p=.0021) in 2002 [1.56 (0.83-2.66)], in 2003 [1.73 (0.95-2.90)] and in 2004 [1.51 (0.74-2.27)]. Non-CNS complications remained stable over time.
  
  
  CONCLUSIONS
  Possible factors biasing the result were taken into account. Reasons of increased CNS complications remain unknown, but the possible emergence of a particularly neurotropic strain of varicella-zoster virus should be further investigated.
authors.affiliation: Department of Pediatrics, University of Florence, Anna Meyer Children's Hospital, Via Luca Giordano, 13, I-50132 Florence, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Frenos
authors.forename: Luisa
authors.initials: L
authors.lastname: Galli
authors.forename: Elena
authors.initials: E
authors.lastname: Chiappini
authors.forename: Maurizio
authors.initials: M
authors.lastname: de Martino
mesh_terms: D000293:Adolescent; D002524:Cerebellar Ataxia / Q000821:virology*; D002644:Chickenpox / Q000150:complications* / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D004660:Encephalitis / Q000821:virology*; D014645:Herpesvirus 3, Human / Q000472:pathogenicity*; D006801:Humans; D015994:Incidence; D007223:Infant; D007558:Italy / Q000453:epidemiology; D008581:Meningitis / Q000821:virology*; D014774:Virulence