Sexually transmitted infections (STIs)

Sexually transmitted infections (STIs) are a major global cause of infertility, acute illness and long-term disability, with severe medical and psychological consequences for millions of men, women and their children across the life-course if not treated. WHO/Europe advocates and assists Member States in the promotion of evidence- and human-rights-based policies and practices for STI control and prevention and in the development of national capacities to implement such policies and practices.

What are STIs?

STIs are spread primarily through person-to-person sexual contact. There are over 30 different sexually transmissible bacteria, viruses and parasites. Several STIs, particularly HIV and syphilis, can be transmitted through blood products and tissue transfer, and from mother to child during pregnancy and childbirth.

Symptoms of STIs may be absent, mild and transient, or (as with gonorrhoea, chancroid, herpes simplex virus) acute. Many STIs can have severe long-term consequences. In adults, chlamydia and gonorrhoea may lead to complications such as infertility, chronic illness and potentially fatal ectopic pregnancy. Chlamydia, gonorrhoea and syphilis can produce serious and often life-threatening conditions in fetuses and newborn babies, such as congenital syphilis, pneumonia and low birth weight. Infection with human papillomavirus is a proven precondition for the development of carcinoma of the cervix, which is the second leading cause of female cancer mortality worldwide.