title: Nationwide increase of Chlamydia trachomatis infection in Finland: highest rise among adolescent women and men.
abstract: BACKGROUND
  Since 1995, the incidence of Chlamydia trachomatis infection has been increasing in Finland, although there have been no major changes in public sexually transmitted disease (STD) services or screening practice.
  
  
  OBJECTIVE
  The objective was to study whether the change in C. trachomatis incidence is significant and to identify specific risk groups.
  
  
  METHODS
  The incidence rates for all C. trachomatis cases notified by laboratories to the National Infectious Disease Register (NIDR) in Finland in 1995-2000 were calculated by gender, age, and domicile. Data from a sentinel STD surveillance network was used to analyze changes of risk-taking behavior in age groups with the highest C. trachomatis rates.
  
  
  RESULTS
  During the 6-year study period, laboratory surveillance data documented an increase in the incidence rate from 23.4 per 10,000 to 29.2 per 10,000. The increase was most evident among people living in nonurban densely populated areas. Highest increase, 1.37-fold (95% confidence interval [CI], 1.29-1.46) in women and 1.69-fold (CI, 1.47-1.92) in men, occurred in the youngest age group (10-19 years old). In 2000, more women, but not men, in the age group of 10-29 years reported 5 or more annual sex partners (18.8%; CI, 16.3-21.6) than in 1995 (8.3%; CI, 5.7-11.5).
  
  
  CONCLUSIONS
  National surveillance of C. trachomatis infection based on laboratory notification documented increasing incidence rates, especially among adolescents and young people. This risk group should be a target for screening and educational programs to control the epidemic of C. trachomatis infections.
authors.affiliation: Department of Dermatology and Venereology, Helsinki University Hospital, Helsinki, Finland. eija.hiltunen-back@hus.fi
authors.forename: Eija
authors.initials: E
authors.lastname: Hiltunen-Back
authors.forename: Olli
authors.initials: O
authors.lastname: Haikala
authors.forename: Hannu
authors.initials: H
authors.lastname: Kautiainen
authors.forename: Petri
authors.initials: P
authors.lastname: Ruutu
authors.forename: Jorma
authors.initials: J
authors.lastname: Paavonen
authors.forename: Timo
authors.initials: T
authors.lastname: Reunala
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D000328:Adult; D000367:Age Factors; D000368:Aged; D002648:Child; D002690:Chlamydia Infections / Q000453:epidemiology* / Q000209:etiology; D002692:Chlamydia trachomatis; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012309:Risk-Taking