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Sexually transmitted infections (STIs)

Sexually transmitted infections (STIs), also referred to as sexually transmitted diseases (STDs), are infections that are commonly spread by sexual activity. Sometimes these infections can be transmitted through non-sexual route, such as from mother to infant during pregnancy or childbirth, or through blood transfusions or shared needles.

Sexually transmitted infections (STIs) and diseases (STDs) are the same thing. They are infections mainly spread by sexual activity, including vaginal, anal and oral sex. Some STIs can be transmitted through a non-sexual route, such as from mother to infant during pregnancy or childbirth, or through blood transfusions or shared needles.

Key facts

  • More than one million sexually transmitted infections (STIs) are acquired every day worldwide.
  • The majority of STIs have no obvious symptoms, or only mild symptoms that may not be recognised as an STI. More than 30 different bacteria, viruses and parasites are known to be transmitted through sexual contact. Eight of them are linked to the most common STIs. Of these, four are currently curable: syphilis, gonorrhoea, chlamydia and trichomoniasis. The other four are incurable viral infections: hepatitis B, herpes simplex virus (HSV or herpes), HIV, and human papillomavirus (HPV).
  • Other infections that can be acquired by sexual contact include monkeypox, Shigella sonneiNeisseria meningitidis, and the Ebola and Zika viruses . 

Health risks

STIs can have serious consequences beyond the immediate impact of the infection itself. 

  •  STIs such as Herpes and syphilis can greatly increase the risk of acquiring 
  • In some cases, STIs can have serious reproductive health consequences, including infertility or mother-to-child transmission.
  • Mother-to-child transmission of STIs can result in stillbirth, neonatal death, low birth weight and prematurity, sepsis, pneumonia, neonatal conjunctivitis, and congenital deformities. 
  • HPV infection causes 570,000 cases of cervical cancer and over 300,000 cervical cancer deaths each year.
  • STIs such as gonorrhoea and chlamydia are major causes of pelvic inflammatory disease (PID) and infertility in women.


  • A person can have an STI without having obvious symptoms of disease. 
  • Common symptoms include vaginal discharge, urethral discharge or burning in men, genital ulcers, and abdominal pain. 
  • Other symptoms include pain when urinating, lumps or skin growths around the genitals or anus, and a rash or itchy genitals or anus.

If you think you have any of the above symptoms then do not have sex, including oral sex, without a condom until you have had a check-up.


Effective treatment is currently available for several STIs.

  • Three bacterial STIs (chlamydia, gonorrhoea and syphilis) and one parasitic STI (trichomoniasis) are generally curable with existing, effective single-dose regimens of antibiotics.
  • For herpes and HIV, the most effective medications available are antivirals that can modulate the course of the disease, though they cannot cure it.
  • For hepatitis B, antiviral medications can help to fight the virus and slow damage to the liver.


  • Correct and consistent use of condoms during vaginal, oral, or anal sex offer one of the most effective methods of protection against STIs, including HIV. 
  • However, condoms do not offer protection for those STIs that cause extra-genital ulcers – syphilis or genital herpes.
  • Avoid sexual acts that tear or break the skin, as these carry a higher risk of STIs. 
  • Vaccinations are available that will help prevent hepatitis B and some types of HPV. 
  • Safe blood transfusion and organ transplantation. 
  • Use of disposable syringes and sterile and safe instrument.
  •  Counselling and behavioural interventions offer primary prevention against STIs including HIV, as well as against unintended pregnancies.


You can also get in touch with the ITF using the ITF Wellbeing app or ITF Wellbeing Facebook page for guidance on sexually transmitted infections, or keep updated via the WHO website.