Prevalence of Chlamydia trachomatis: results from the first national population-based survey in France

International audienceObjectives: Few studies have estimated Chlamydia trachomatis (CT) prevalence in the general population, most prevalence studies being based on people already attending healthcare settings. We estimated the prevalence of CT in France, assessed the feasibility of home sampling without any face-to-face intervention, and identified risk factors associated with CT infection using data from the Contexte de la Sexualité (CSF) survey on sexual behaviour. Methods: CSF was a national population-based survey, carried out by telephone in 2006. A random subsample of sexually experienced individuals aged 18-44 (N=4957) were invited to participate in a CT home-sampling study (NatChla Study). Participants were tested for CT by PCR. Percentages were weighted for unequal selection probabilities and post-stratified based on French population census data. Independent risk factors were identified by logistic regression. Results: CT prevalence in individuals aged 18-44 was estimated at 1.4 % [95 % CI: 0.8- 2.6] for men, and 1.6 % [95%CI:1.0- 2.5] for women. We observed increased rates in individuals aged 18-29: 2.5 % [95%CI:1.2-5.0] for men and 3.2 % [95%CI:2.0 -5.3] for women. CT infection was associated, for both genders, with having their last sexual intercourse with a casual or new partner. Other risk factors were for men, living in the Paris area, and for women, multiple partners during the previous year, same sex partners and a low level of education. Conclusions: CT prevalence in France is similar to other developed countries. Home-sampling proved feasible and useful to reach members of the population with limited access to traditional care