What is chlamydia?

Dr Sarah Jarvis MBE Chlamydia is a sexually transmitted infection (STI) caused by a germ (bacterium) called Chlamydia trachomatis. Around 3 to 7 in 100 sexually active young people in the UK are infected with chlamydia. It is most common in those aged under 25. For more information, go to https://patient.info/health/sexually-transmitted-infections-leaflet/chlamydia