Epidemiology of sexually transmitted infections: worldwide

Sexually transmitted infections (STIs) cause an enormous burden of disease, especially among poor people, women and children. Those caused by bacteria and protozoa can be cured, often with single-dose treatment, whereas the viral infections, genital herpes and HIV, are lifelong, incurable infections. Other STIs, especially those which cause genital ulceration, facilitate the sexual transmission of HIV. Since a high proportion of STIs are asymptomatic, especially in women, their control depends on screening and treatment of populations at risk, as well as the provision of effective treatment for those with symptoms. Syndromic treatment for those with symptoms is recommended where laboratory testing is not feasible or may lead to a delay in treatment. Simple point-of-care (POC) screening tests are available for HIV, syphilis and Trichomonas vaginalis, but currently available POC tests for Chlamydia trachomatis are less sensitive than laboratory-based tests. Treatment of sexual partners is another cornerstone of STI control.