16.7 - STIs

STIs and how they spread

• A sexually transmitted infection (STI) is an infection passed on through sexual contact, including sexual intercourse.
• The pathogens are carried in body fluids exchanged during sex, so an STI spreads from an infected person to a partner during unprotected sexual contact.

HIV - The main example

• HIV (the human immunodeficiency virus) is spread mainly in infected body fluids - blood, semen and vaginal fluids - during sex.
• It can also be passed on in other ways:
  • By drug users sharing needles
  • From an infected mother to her baby during pregnancy, childbirth or breastfeeding
• An untreated HIV infection may eventually lead to AIDS (acquired immune deficiency syndrome), in which the person's immune system gradually fails and they become very vulnerable to other infections.

Preventing the spread of STIs

The spread of STIs (sexually transmitted infections) can be reduced in several ways:

• Using a condom - Acts as a barrier during sex that stops body fluids, and the pathogens they carry, being passed between partners.
• Limiting the number of sexual partners - Reduces the chance of meeting an infected partner.
• Abstinence - Avoiding sexual contact altogether is the only way to be certain an STI isn't passed on this way.
• Screening and testing - Finds infections, including ones causing no symptoms, so infected people can be treated and avoid passing the infection on. Testing is especially important after unprotected sex or contact with several partners.
• Medication - Can reduce the chance of an infected person passing the infection on during sex, or of an infected mother passing it to her baby.
• Not sharing needles - People who inject drugs should not share needles, as this passes infected blood between them.
• Education and vaccination - Making people aware of STIs and how they spread helps them avoid risky behaviour, and some viral STIs can be protected against by vaccination.