Up to 10% of young people are infected with chlamydia. Here's the Quick Fire Science, from Phil Sansom...Chlamydia is a bacterial infection. It's one of the most common STIs - sexually transmitted infections - in the UK.It's easy to be infected with it without realising, because many people with chlamydia have no symptoms.For those that do have symptoms, they can become apparent a few weeks after you're infected. You might experience a discharge from the vagina or penis, or a burning sensation while urinating. For women there may also be bleeding after sex or between periods; for men, there... Like this podcast? Please help us by supporting the Naked Scientists