Scientists have been looking into why some sex workers are resistant to HIV despite frequent unprotected sex in a country where the HIV rate is high. The women they studied did not develop HIV and researchers have previously been unaware why this is the case.
Sexually transmitted infections (or STIs) are still common in the UK. In 2014, nearly half a million cases were diagnosed in England alone. Here are some of the more common STIs along with their symptoms and how to treat them.