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

BACKGROUND: Few studies have estimated Chlamydia trachomatis (CT) prevalence in the general population, most prevalence studies being based on people already attending healthcare settings.

OBJECTIVES: To estimate the prevalence of CT in France, assess the feasibility of home sampling without any face-to-face intervention and identify risk factors associated with CT infection using data from the Contexte de la Sexualité (CSF) survey on sexual behaviour; a national population-based survey, carried out by telephone in 2006.

METHODS: A random subsample of sexually experienced people aged 18-44 (N=4957) were invited to participate in a CT home-sampling study (NatChla study). Participants' samples 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 people aged 18-44 was estimated at 1.4% (95% CI 0.8% to 2.6%) for men, and 1.6% (95% CI 1.0% to 2.5%) for women. Increased rates were found in subjects aged 18-29: 2.5% (95% CI 1.2% to 5.0%) for men and 3.2% (95% CI 2.0% to 5.3%) for women. CT infection was associated, for both genders, with having their last sexual intercourse with a casual partner. Other risk factors were for men, having last intercourse with a new partner, 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 that in other developed countries. Home sampling proved feasible and useful to reach members of the population with limited access to traditional care.