Genital chlamydia is a sexually transmitted infection caused by the Chlamydia trachomatis bacterium. Sexually active young people are most at risk of chlamydia, and women below 24 years of age have the highest number of infections in Europe.
Chlamydia trachomatis infections can cause long-term complications in women even when they do not produce symptoms of acute disease. The most common complications are pelvic inflammatory disease (PID) and salpingitis, conditions that can lead to infertility and extra-uterine pregnancies. This risk of long-term reproductive health problems associated with C. trachomatis infections has lead some European countries to routinely offer testing for chlamydia to sexually active young people in an attempt to reduce the spread of the disease.