Sexually transmitted infections

Posted: 26 September 2007

Sexually transmitted infections (STIs) are among the most common causes of illness in the world and have far-reaching health, social and economic consequences. In addition to their sheer magnitude, STIs are a major public health problem for two additional reasons: their serious effects on women's health and fertility, and the fact that they facilitate transmission of HIV.

Global map showing estimated new cases of STIs, 1999 (WHO).

  • More than 1 million women and children died from the complications of reproductive tract infections, including sexually transmitted infections other than HIV/AIDS, every year during the 1990s.
  • There are an estimated 340 million new cases of STIs per year. In Sub-Saharan Africa alone, there are 69 million new cases of curable STIs every year - the highest rate of new cases per 1000 population of any region.

  • Despite the availability of effective treatment, STIs collectively rank second in importance among treatable diseases among women aged 15-44 worldwide. Four curable STDs - gonorrhoea, chlamydia, syphilis and trichomoniasis - rank among the top five causes of healthy days of life lost in sub-Saharan Africa.

  • In women of childbearing age in developing countries, STIs (excluding HIV) are second only to maternal factors as causes of disease, death and healthy life lost.

  • Gonorrhoea and chlamydial infection cause pelvic inflammatory disease in women and impair the fertility of both men and women. They also cause increased risk of ectopic pregnancy, a condition that can kill from sudden and severe internal bleeding following rupture of the fallopian tube.

  • Some STIs attack the fetus and infant as well. In two-thirds or more of pregnant women with early syphilis, for example, the infection spreads through the placenta and infects the fetus and because of this up to one-half of syphilis-infected pregnancies end in spontaneous abortion, stillbirth, or perinatal death. Gonorrhoea or chlamydia may likewise infect the eyes of babies as they pass through the cervix and vagina during birth, while chlamydia may spread to the lungs of newborns, resulting in chlamydial pneumonia.

  • Young adults between 15 and 19 years of age often have high rates of STI and present a particularly important problem because of their lack of easy access to STI services and condoms, and their frequent and multiple casual sex partners.