title: Varicella and herpes zoster in Madrid, based on the Sentinel General Practitioner Network: 1997-2004.
abstract: BACKGROUND
  Varicella (chickenpox) is the primary disease caused by varicella-zoster virus. It is extremely contagious and is frequent in children. Indeed, in the absence of vaccination, a high proportion of the population is liable to contract it. Herpes zoster -more frequent among adults- is caused by reactivation of the latent virus. The objective of this study is to describe the status of and time trend for varicella and herpes zoster in the Madrid Autonomous Region prior to the introduction of the vaccine to the general population.
  
  
  METHODS
  
  
  
  METHODS
  individualised varicella and herpes zoster case records kept by the Madrid Autonomous Region Sentinel General Practitioner Network for the period 1997-2004. Cumulative incidences, crude and standardised incidence rates, and age-specific rates of varicella and herpes zoster were calculated for each year. Kendall's Tau-b correlation coefficient was calculated to evaluate whether incidence displayed a time trend. Spectral density in the time series of weekly incidences was estimated using a periodogram.
  
  
  RESULTS
  Standardised annual varicella incidence rates ranged from 742.5 (95% CI: 687.2-797.7) to 1239.6 (95% CI: 1164.5-1313.4) cases per 100 000 person-years. Most cases affected children, though complications were more frequent in adults. Varicella incidence displayed an annual periodicity but no trend over time. Most herpes zoster cases occurred at advanced ages, with incidence registering a rising annual trend but no seasonality factor.
  
  
  CONCLUSIONS
  In the absence of vaccination, no significant changes in varicella incidence were in evidence recent years, though these were observed in the incidence of herpes zoster. Sentinel general practitioner networks are a valid instrument for surveillance of diseases such as varicella. Further varicella vaccination-coverage and vaccine-efficacy studies are called for.
authors.affiliation: Department of Epidemiology, Madrid Public Health Institute, Julián Camarillo 4B, Madrid, Spain. napoleon.perez@salud.madrid.org
authors.forename: Napoleón
authors.initials: N
authors.lastname: Pérez-Farinós
authors.forename: María
authors.initials: M
authors.lastname: Ordobás
authors.forename: Cristina
authors.initials: C
authors.lastname: García-Fernández
authors.forename: Luis
authors.initials: L
authors.lastname: García-Comas
authors.forename: Soledad
authors.initials: S
authors.lastname: Cañellas
authors.forename: Inmaculada
authors.initials: I
authors.lastname: Rodero
authors.forename: Angeles
authors.initials: A
authors.lastname: Gutiérrez-Rodríguez
authors.forename: Juan
authors.initials: J
authors.lastname: García-Gutiérrez
authors.forename: Rosa
authors.initials: R
authors.lastname: Ramírez
mesh_terms: D000293:Adolescent; D000328:Adult; D002644:Chickenpox / Q000150:complications / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D005194:Family Practice / Q000706:statistics & numerical data; D005260:Female; D006562:Herpes Zoster / Q000150:complications / Q000453:epidemiology*; D014645:Herpesvirus 3, Human / Q000472:pathogenicity*; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D012189:Retrospective Studies; D018571:Sentinel Surveillance; D013030:Spain / Q000453:epidemiology