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Low prevalence of Chlamydia trachomatisinfection in asymptomatic young Swiss men



Prevalence and risk factors for Chlamydia trachomatis infection among young men in Switzerland is still unknown. The objective of the present study was to assess prevalence and risk factors for C. trachomatis infection in young Swiss men.


517 young Swiss men were enrolled in this cross-sectional study during their compulsory military recruitment. Participants completed a questionnaire and gave urine samples which were screened for C. trachomatis DNA by PCR. Genotyping of positive samples was done by amplification and sequencing the ompA gene.


The prevalence of chlamydial infection among young Swiss male was 1.2% (95% confidence interval [95%CI], 0.4–2.5%). C. trachomatis infection was only identified among the 306 men having multiple sexual partner. Although frequent, neither unprotected sex (absence of condom use), nor alcohol and drug abuse were associated with chlamydial infection. Men living in cities were more frequently infected (2.9%, 95%CI 0.8–7.4%) than men living in rural areas (0.5%, 95%CI 0.1–1.9%, p = 0.046). Moreover, naturalised Swiss citizens were more often positive (4.9%, 95%CI 1.3–12.5%) than native-born Swiss men (0.5%, 95%CI 0.1–1.7%, p = 0.003).


In comparison with other countries, the prevalence of chlamydial infection in men is extremely low in Switzerland, despite a significant prevalence of risky sexual behaviour. C. trachomatis infection was especially prevalent in men with multiple sexual partners. Further research is required (i) to define which subgroup of the general population should be routinely screened, and (ii) to test whether such a targeted screening strategy will be effective to reduce the prevalence of chlamydial infection among this population.

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Chlamydia trachomatis infection is the commonest sexually transmitted bacterial disease in European countries [1, 2] and in the United States [3, 4]. Although the major impact of disease is on the female genital tract [1, 2], men may suffer from urethritis, prostatitis, infertility and Reiter's syndrome [1].

The most frequent risk factors associated with chlamydial infection are related to sexual behaviour, i.e. early age of first intercourse, multiple partners, and inconsistent condom use [1]. Since most infections caused by C. trachomatis are asymptomatic, the establishment of screening programs, as already done in some developed countries, is necessary to control the disease [5].

The studies carried out in Europe on C. trachomatis infection among young males have shown high rates ranging from 7.8–13.3%[1, 611]. Similar prevalence were observed in other developed (3.7–5.3% [4, 1214]) and developing countries (3.1–7.9% [15, 16]).

However, no data are available from Switzerland. The present cross-sectional study is intended to determine the prevalence of and risk factors for C. trachomatis infection among young healthy Swiss males.


In this study approved by the ethical committee of the University of Lausanne (n° 177/06), we included all 18–26 years-old Swiss men who presented for their medical entry examination at the Army Recruitment Centre of Lausanne, Switzerland during winter 2006–2007 and who gave written consent for urinary C. trachomatis screening. The volunteers completed a questionnaire on sociodemographic, sexual and behavioral risk factors. Our questionnaire was adapted from questionnaires used in previous published studies measuring sexually transmitted infections [6, 12, 1719]. Completion of the questionnaire was accurately done, since answers to similar and complementary questions formulated in different ways were 97% and 95% congruent for demographic questions and for questions on their sexual activities, respectively. DNA was extracted from centrifuged first-void urine and analyzed by real-time Taqman PCR, as described [20]. This PCR exhibited an excellent analytical sensitivity of 1 copy per reaction, good intrarun and interrun reliability, and a specificity of 100% when considering Cobas Amplicor as gold standard [20]. Positive samples were then genotyped using ompA sequencing [21]. Statistical analyses were performed using STATA (College-Station, USA). Confidence Intervals were calculated using the Daly method [22].


Among 521 eligible men, four did not complete the questionnaire and were excluded. The sociodemographic characteristics of the 517 remaining volunteers are shown in Table 1. The mean age was 20.6 years (standard deviation ± 1.4 years). A total of 87% of the participants reported being sexually-experienced and 59.9% of the participants reported having more than two sexual partners in their life span. The consistent use of condoms for all sexual relations was reported by 32.3% of the 517 volunteers. Among those with more than 4 partners (n = 178), 21.3% regularly used condoms. While 67.9% of the study participants drank alcohol at least every week-end, 3.5% drank alcohol every day. Almost half (47.6%) of the participants were cigarette smokers, and 28.1% of them smoke more than 20 cigarettes per day. Occasional or daily cannabis consumption was reported by 27.1% and 7.8% of the participants, respectively. Ecstasy, heroin or cocaine have been taken by 6.4% of the studied population.

Table 1 Chlamydia trachomatis prevalence according to various demographic and behavioural variables

The prevalence of chlamydial infection was 1.2% (95%CI 0.4–2.5%) among all 517 volunteers and of 1.3% (95%CI 0.3–2.4%) among the 450 sexually-experienced men. No participants without or with only a single lifetime sexual partner were diagnosed with chlamydial infection. Conversely, 1.9% (95%CI 0.7–4.2%) of those with multiple sexual partners were C. trachomatis positive. Two men who tested positive for Chlamydia reported having consistently used condoms during all sexual relations. Among the 9 men who reported having had a male sexual partner, none had a positive Chlamydia test. When considering only Swiss born men, the prevalence was 0.5% (95%CI 0.2–2.1%). Conversely, among foreign born naturalized men who originated from Europe, the prevalence was 2.4% (95CI 0.1–13.3%). For those originated from foreign countries outside Europe, a prevalence of 7.5% (95%CI 1.5–21.9%) was observed. Young men living in cities more than 10'000 inhabitants and/or earning more than 2000 SFrs (1600 US$) were at increased risk of C. trachomatis infection (Table 1). Alcohol, cigarette, cannabis and illegal drug consumption were frequently recorded, but were not associated with chlamydial infection. Chlamydial serotypes were E (n = 3), J, Ia and D (n = 1 each).


Our cross-sectional study provides, for the first time, prevalence data of C. trachomatis infection in young Swiss men. In Switzerland, previous studies mainly focused on women and evaluated highly selected study populations [23]. A 2.8% prevalence was recorded among asymptomatic sexually active Swiss women in 1998 [23]. However, studied women were mainly from urban area, where the prevalence is higher. Moreover, age of first sexual intercourse is lower for women or occur with older partner [24], likely also contributing to increased prevalence in women. C. trachomatis is a reportable disease in Switzerland. Since 1999, there has been a significant increase (64%) in the number of official reports of C. trachomatis infection in Switzerland [25, 26]. However, among the 517 asymptomatic young Swiss men we investigated, the prevalence was only 1.2%. This Chlamydia prevalence is much lower than that reported for young asymptomatic males in Norway (7.8%)[6], Scotland (9.8%) [8] and the entire UK (13.3%) [1]. In USA, prevalence is also higher than that found in Switzerland, ranging from 3.7% [4] to 5.3% [13].

Multiple partners and inconsistent condom use are recognised as important predictors of C. trachomatis infection [1, 6, 16]. However, screening on the basis of condom use would have missed a substantial number of infections in the population we studied, since two of six infected men reported having always used condoms. The effect or no effect of condom use as a preventive mesure should ideally be confirmed in a larger cohort. In our study, variables associated with C. trachomatis infection were "multiple sexual partners", "living in a large city" and "foreign born, naturalized". The higher prevalence observed in the latter subgroup, similar to that of other European and non-European countries, demonstrate that the overall low prevalence of 1.2% we observed was not due to a low sensitivity of the PCR, but rather reflects a true local difference in prevalence. Serotype E was more prevalent in Switzerland, as it is the case in other European countries [21, 27].


This is the first study of the prevalence of C. trachomatis infection conducted in young Swiss males. Since military service is compulsory for all Swiss men, the study population we screened corresponds to an unselected and unbiased representative sample of young healthy Swiss men. Despite a prevalence of sexual risk behaviour which is similar to that recorded in other countries [24], C. trachomatis prevalence in Swiss males is extremely low. In the future, in order to identify populations with a high prevalence that may benefit from mass screening, it will be important to more precisely identify risks factors associated with chlamydial infection.


  1. 1.

    Manavi K: A review on infection with Chlamydia trachomatis. Best Pract Res Clin Obstet Gynaecol. 2006, 20: 941-951. 10.1016/j.bpobgyn.2006.06.003.

    Article  PubMed  Google Scholar 

  2. 2.

    Fenton KA, Lowndes CM: Recent trends in the epidemiology of sexually transmitted infections in the European Union. Sex Transm Infect. 2004, 80: 255-263. 10.1136/sti.2004.009415.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  3. 3.

    Schillinger JA, Dunne EF, Chapin JB, Ellen JM, Gaydos CA, Willard NJ, Kent CK, Marrazzo JM, Klausner JD, Rietmeijer CA, Markowitz LE: Prevalence of Chlamydia trachomatis infection among men screened in 4 U.S. cities. Sex Transm Dis. 2005, 32: 74-77. 10.1097/

    Article  PubMed  Google Scholar 

  4. 4.

    Miller WC, Ford CA, Morris M, Handcock MS, Schmitz JL, Hobbs MM, Cohen MS, Harris KM, Udry JR: Prevalence of chlamydial and gonococcal infections among young adults in the United States. JAMA. 2004, 291: 2229-2236. 10.1001/jama.291.18.2229.

    CAS  Article  PubMed  Google Scholar 

  5. 5.

    Low N: Screening programmes for chlamydial infection: when will we ever learn?. BMJ. 2007, 334: 725-728. 10.1136/bmj.39154.378079.BE.

    Article  PubMed  PubMed Central  Google Scholar 

  6. 6.

    Bakken IJ, Skjeldestad FE, Halvorsen TF, Thomassen T, Storvold G, Nordbo SA: Chlamydia trachomatis among young Norwegian men: sexual behavior and genitourinary symptoms. Sex Transm Dis. 2007, 34: 245-249. 10.1097/01.olq.0000233737.48630.03.

    Article  PubMed  Google Scholar 

  7. 7.

    Wagenlehner FM, Weidner W, Naber KG: Chlamydial infections in urology. World J Urol. 2006, 24: 4-12. 10.1007/s00345-005-0047-x.

    Article  PubMed  Google Scholar 

  8. 8.

    McKay L, Clery H, Carrick-Anderson K, Hollis S, Scott G: Genital Chlamydia trachomatis infection in a subgroup of young men in the UK. Lancet. 2003, 361: 1792-10.1016/S0140-6736(03)13398-3.

    Article  PubMed  Google Scholar 

  9. 9.

    Lamontagne DS, Fenton KA, Randall S, Anderson S, Carter P: Establishing the National Chlamydia Screening Programme in England: results from the first full year of screening. Sex Transm Infect. 2004, 80: 335-341. 10.1136/sti.2004.012856.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  10. 10.

    Kang M, Rochford A, Johnston V, Jackson J, Freedman E, Brown K, Mindel A: Prevalence of Chlamydia trachomatis infection among 'high risk' young people in New South Wales. Sex Health. 2006, 3: 253-254. 10.1071/SH06025.

    Article  PubMed  Google Scholar 

  11. 11.

    van der Snoek EM, Gotz HM, Mulder PG, Verkooyen RP, van der Meijden WI: Prevalence of STD and HIV infections among attenders of the Erasmus MC STD clinic, Rotterdam, The Netherlands, during the years 1996 to 2000. Int J STD AIDS. 2003, 14: 119-124. 10.1258/095646203321156890.

    CAS  Article  PubMed  Google Scholar 

  12. 12.

    Arcari CM, Gaydos JC, Howell MR, McKee KT, Gaydos CA: Feasibility and short-term impact of linked education and urine screening interventions for Chlamydia and gonorrhea in male army recruits. Sex Transm Dis. 2004, 31: 443-447. 10.1097/01.OLQ.0000129950.91427.34.

    Article  PubMed  Google Scholar 

  13. 13.

    Cecil JA, Howell MR, Tawes JJ, Gaydos JC, McKee KT, Quinn TC, Gaydos CA: Features of Chlamydia trachomatis and Neisseria gonorrhoeae infection in male Army recruits. J Infect Dis. 2001, 184: 1216-1219. 10.1086/323662.

    CAS  Article  PubMed  Google Scholar 

  14. 14.

    Scholes D, Heidrich FE, Yarbro P, Lindenbaum JE, Marrazzo JM: Population-Based Outreach for Chlamydia Screening in Men: Results from a Randomized Trial. Sex Transm Dis. 2007

    Google Scholar 

  15. 15.

    Buve A, Weiss HA, Laga M, Van DE, Musonda R, Zekeng L, Kahindo M, Anagonou S, Morison L, Robinson NJ, Hayes RJ: The epidemiology of gonorrhoea, chlamydial infection and syphilis in four African cities. AIDS. 2001, 15 Suppl 4: S79-S88. 10.1097/00002030-200108004-00009.

    CAS  Article  PubMed  Google Scholar 

  16. 16.

    Fioravante FC, Costa Alves MF, Guimaraes EM, Turchi MD, Freitas HA, Domingos LT: Prevalence of Chlamydia trachomatis in asymptomatic Brazilian military conscripts. Sex Transm Dis. 2005, 32: 165-169. 10.1097/01.olq.0000152897.44969.02.

    Article  PubMed  Google Scholar 

  17. 17.

    Jennings JM, Luo RF, Lloyd LV, Gaydos C, Ellen JM, Rietmeijer CA: Age-bridging among young, urban, heterosexual males with asymptomatic Chlamydia trachomatis. Sex Transm Infect. 2006

    Google Scholar 

  18. 18.

    Marrazzo JM, Ellen JM, Kent C, Gaydos C, Chapin J, Dunne EF, Rietmeijer CA: Acceptability of urine-based screening for Chlamydia trachomatis to asymptomatic young men and their providers. Sex Transm Dis. 2007, 34: 147-153. 10.1097/01.olq.0000230438.12636.eb.

    Article  PubMed  Google Scholar 

  19. 19.

    Fenton KA, Korovessis C, Johnson AM, McCadden A, McManus S, Wellings K, Mercer CH, Carder C, Copas AJ, Nanchahal K, Macdowall W, Ridgway G, Field J, Erens B: Sexual behaviour in Britain: reported sexually transmitted infections and prevalent genital Chlamydia trachomatis infection. Lancet. 2001, 358: 1851-1854. 10.1016/S0140-6736(01)06886-6.

    CAS  Article  PubMed  Google Scholar 

  20. 20.

    Jaton K, Bille J, Greub G: A novel real-time PCR to detect Chlamydia trachomatis in first-void urine or genital swabs. J Med Microbiol. 2006, 55: 1667-1674. 10.1099/jmm.0.46675-0.

    CAS  Article  PubMed  Google Scholar 

  21. 21.

    Lysen M, Osterlund A, Rubin CJ, Persson T, Persson I, Herrmann B: Characterization of ompA genotypes by sequence analysis of DNA from all detected cases of Chlamydia trachomatis infections during 1 year of contact tracing in a Swedish County. J Clin Microbiol. 2004, 42: 1641-1647. 10.1128/JCM.42.4.1641-1647.2004.

    CAS  Article  PubMed  PubMed Central  Google Scholar 

  22. 22.

    Daly L: Simple SAS macros for the calculation of exact binomial and Poisson confidence limits. Comput Biol Med. 1992, 22: 351-361. 10.1016/0010-4825(92)90023-G.

    CAS  Article  PubMed  Google Scholar 

  23. 23.

    Paget WJ, Zbinden R, Ritzler E, Zwahlen M, Lengeler C, Sturchler D, Matter HC: National laboratory reports of Chlamydia trachomatis seriously underestimate the frequency of genital chlamydial infections among women in Switzerland. Sex Transm Dis. 2002, 29: 715-720. 10.1097/00007435-200211000-00016.

    Article  PubMed  Google Scholar 

  24. 24.

    Wellings K, Collumbien M, Slaymaker E, Singh S, Hodges Z, Patel D, Bajos N: Sexual behaviour in context: a global perspective. Lancet. 2006, 368: 1706-1728. 10.1016/S0140-6736(06)69479-8.

    Article  PubMed  Google Scholar 

  25. 25.

    Abraham S, Toutous-Trellu L, Pechere M, Hugonnet S, Liassine N, Yerly S, Rohner P, Ninet B, Hirschel B, Piguet V: Increased incidence of sexually transmitted infections in Geneva, Switzerland. Dermatology. 2006, 212: 41-46. 10.1159/000089021.

    Article  PubMed  Google Scholar 

  26. 26.

    Lautenschlager S: Sexually transmitted infections in Switzerland: return of the classics. Dermatology. 2005, 210: 134-142. 10.1159/000082569.

    Article  PubMed  Google Scholar 

  27. 27.

    Jonsdottir K, Kristjansson M, Hjaltalin OJ, Steingrimsson O: The molecular epidemiology of genital Chlamydia trachomatis in the greater Reykjavik area, Iceland. Sex Transm Dis. 2003, 30: 249-256. 10.1097/00007435-200303000-00015.

    Article  PubMed  Google Scholar 

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We thank all employees from the Recruitment Centre of the Swiss Army who were involved in this study. We particularly thank Cordula Equey and Manuela Bersier for help for sampling, André Baud for computer assistance, and Ana Palma for technical assistance. We also thank Philip E. Tarr and Anthony Staines (reviewer) for their critical review of the manuscript. Gilbert Greub is supported by the Leenards Foundation through a "Bourse Leenards pour la relève académique en médecine clinique à Lausanne".

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Correspondence to Gilbert Greub.

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The author(s) declare that they have no competing interests.

Authors' contributions

DB and GG initiated and designed the study, interpreted the results. DB, CB and GG performed the statistical analyses. DB and JPK were responsible for patient recruitment, clinical assessment, data management and blood sampling. KJ and GG did the laboratory analyses. The paper was written by DB and GG, and reviewed by all other contributors.

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Baud, D., Jaton, K., Bertelli, C. et al. Low prevalence of Chlamydia trachomatisinfection in asymptomatic young Swiss men. BMC Infect Dis 8, 45 (2008).

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  • Prostatitis
  • Ecstasy
  • Chlamydial Infection
  • Multiple Sexual Partner
  • Inconsistent Condom