title: Epidemic sindbis virus infection in Finland: a population-based case-control study of risk factors.
abstract: BACKGROUND
  Sindbis virus (SINV) is an arthropod-borne alphavirus that causes rash and arthritis. In Finland, epidemics occur cyclically, but factors associated with clinical SINV infection are largely unknown. We conducted a population-based case-control study during the epidemic year 2002.
  
  
  METHODS
  SINV cases were serologically confirmed and reported to the National Infectious Disease Registry. Five control subjects, matched for age, sex, and residence, were selected from the National Population Information System. Data were collected using a self-administered mail survey. Conditional logistic regression models were used to identify independent risk factors; missing data were addressed using Bayesian full-likelihood modeling.
  
  
  RESULTS
  A total of 337 case patients (58% female; age range, 1-94 y) and 934 control subjects were enrolled. Reported exposure to mosquito bites (matched odds ratio [mOR], 16.7; 95% confidence interval [CI], 9.1-33.4) and spending time in woods or marshland (mOR, 1.8; 95% CI, 1.3-2.5) were independently associated with SINV infection in the multivariable model. The population-attributable risk for mosquito bites was 87.2%. There were dose-response relations for increased number of insect bites (mOR, 23.8-72.5) and increased time spent in woods or marshland (mOR, 1.3-2.2).
  
  
  CONCLUSIONS
  Educating the public in endemic areas to avoid mosquito exposure and use protective measures remain important prevention measures for SINV infection.
authors: Department of Virology, Haartman Institute, Helsinki, Finland.
authors: Jussi
authors: J
authors: Sane
authors: Sandra
authors: S
authors: Guedes
authors: Jukka
authors: J
authors: Ollgren
authors: Satu
authors: S
authors: Kurkela
authors: Peter
authors: P
authors: Klemets
authors: Olli
authors: O
authors: Vapalahti
authors: Eija
authors: E
authors: Kela
authors: Outi
authors: O
authors: Lyytikäinen
authors: J Pekka
authors: JP
authors: Nuorti
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018354:Alphavirus Infections / Q000453:epidemiology / Q000209:etiology*; D000818:Animals; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D009033:Culicidae; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D007223:Infant; D007299:Insect Bites and Stings / Q000150:complications; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012307:Risk Factors; D012845:Sindbis Virus