Sexually transmitted infections (STIs)

The majority of sexually transmitted infections (STIs) are caused by bacteria or parasites.

Published on 12 March 2024

In brief

The majority of sexually transmitted infections (STIs) are caused by bacteria or parasites (chlamydia, gonorrhoea, trichomoniasis, syphilis) or viruses (genital herpes, human papillomavirus or HPV, hepatitis B and HIV).

Every year, 374 million people are infected with a bacterial or parasitic STI, which is possible to cure, unlike viral STIs. Nevertheless, they all represent a risk to sexual and reproductive health (cancer, sterility, impact on pregnancy and newborns, increased risk of contracting HIV, etc.). Research is focused not just on prevention, diagnosis, treatment and resistance to treatment, and the development of vaccines, but also on non-medical interventions. These include information on risky practices (chemsex, non-use of condoms, etc.) and facilitating access to screening and care. Our agency supports the WHO global strategy to end STI epidemics by 2030.