How the infections are spread

Sexually transmitted infections are usually spread when infected blood, semen or vaginal fluid come into contact with another person during sex. But some infections (such as HIV and hepatitis B and C) can be spread through infected blood, when needles and other injecting equipment are shared.

Different infections can be passed on to either partner through different sexual activities:

• Chlamydia, NSU, gonorrhoea, hepatitis B and HIV infections are usually spread through penetrative vaginal, anal or oral sex (when the penis enters the vagina, anus or mouth).

• Trichomonas vaginalis (TV) is spread by vaginal sex, and though men may carry it, they usually do not have any symptoms. It can be passed on by sex between women if fluid from the vagina is exchanged - by sharing sex toys, for example.