What We Do
Chlamydial infections are caused by Chlamydia trachomatis. Serovar L of this bacterium is responsible for lymphogranuloma venereum (LGV), also known as Nicolas-Favre disease. Infections with Chlamydia trachomatis are among the sexually transmitted infections on the rise.
While these infections do not always cause visible symptoms in the person infected, they can have serious consequences, such as an increased risk of HIV infection or infertility, especially in women. Nearly 61,100 people were diagnosed and treated for Chlamydia trachomatis infection in the private sector in France in 2024.
To be effective and help reduce the incidence of HIV and other STIs, prevention must rely on a combination of various prevention tools: condom use, repeated and regular testing for HIV and other STIs such as Chlamydia, and appropriate treatment. Particular attention is given to the issue of testing in order to reduce the time between infection and diagnosis and ensure early initiation of treatment.
For Santé publique France, the challenge is to successfully support and implement this new preventive standard among priority populations such as men who have sex with men (MSM), particularly young MSM. Epidemiological surveillance and a better understanding of target audiences and their environments enable Santé publique France to tailor prevention campaigns for them as effectively as possible.
Surveillance of Chlamydia trachomatis infections
Epidemiological surveillance
Surveillance of Chlamydia trachomatis infections relies on several systems.
SurCeGIDD Surveillance: All CeGIDDs are legally required to participate in this surveillance, which covers screening and diagnosis of HIV infection, viral hepatitis, syphilis, Chlamydia trachomatis, gonococcal, and Mycoplasma genitalium infections, genital warts, and genital herpes (individual sociodemographic, behavioral, clinical, and biological data). The required data format is available on the Santé publique France website.
Data from the National Health Data System (SNDS): Health insurance reimbursement data enable the monitoring of Chlamydia trachomatis testing activity conducted in private and public laboratories (excluding public sector hospitalizations). They also enable the monitoring of Chlamydia trachomatis diagnoses.
Anachla surveys: Surveillance of rectal STIs and rectal Chlamydia trachomatis infections caused by non-L strains is conducted through annual surveys over a three-month period via a network of laboratories and clinicians coordinated by the National Reference Center for Bacterial STIs. Learn more about the components of the STI surveillance system on the CNR for Bacterial STIs website and download the various documents.
If you wish to participate in STI surveillance, contact Santé publique France (SurveillanceIST@santepubliquefrance.fr).
This surveillance work is carried out in collaboration with the CNR for Bacterial STIs.
Transition of the Rénachla network to a survey of all French bacteriology laboratories
Starting in 2018, the continuous collection of individual data via the Rénago laboratory network—which helped track the dynamics of Chlamydia trachomatis infections—has been replaced by the “LaboIST” survey. This survey was conducted in 2017 among all private and public clinical laboratories. It collected data for the year 2016 on the number of people tested for Neisseria gonorrhoeae and the number of positive diagnoses by age and sex. This survey was repeated in 2019 by contacting the laboratories’ legal entities to obtain data corresponding to samples collected from January 1 to December 31, 2018. This approach has the advantage of reducing the workload on laboratories by collecting data in an aggregated format, while also enabling the estimation of the total number of STIs and providing data on other STIs (notably syphilis and Mycoplasma genitalium infections).
Measuring Changes in Prevention Behaviors
In addition to epidemiological surveillance of HIV, Santé publique France conducts several surveys among the general population and specific groups. These surveys serve as decision-making tools for public health policy.
Learn more: sexual health section
Prevention efforts against Chlamydia trachomatis infections
Santé publique France designs social marketing initiatives tailored to different priority populations: the general public, young people, men who have sex with men (MSM), and migrants. The goal of this approach is to change behaviors and help the public adopt habits and attitudes that promote sexual health.
Learn more on our prevention websites:
In relation to
Gonorrhea
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On the rise between 2022 and 2024, and more common among men (particularly those aged 26–49) and young people, gonorrhea is a sexually transmitted infection caused by the gonococcus bacterium....
Syphilis
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Caused by the bacterium Treponema pallidum, syphilis is sexually transmitted. It can also be transmitted from mother to child during pregnancy. This disease can affect all organs and have serious...
Sexual health
thematic dossier
Santé publique France focuses in particular on four areas of sexual health: sexually transmitted infections, including HIV; contraception; combating discrimination; and violence.
