Sexually Transmitted Infections (Cambridge International IGCSE Science)

STIs & HIV/AIDS

• Unprotected sexual intercourse can lead to the transfer of pathogens via exchange of body fluids
• Infections passed on in this way are known as sexually transmitted infections (STIs)

How HIV Affects the Immune System

• HIV (Human Immunodeficiency Virus) is an example of an STI

• HIV is a viral pathogen

• The virus infects the body's immune system and decreases the body’s ability to fight infection, eventually leading to AIDS(Acquired Immunodeficiency Syndrome)

• HIV can be spread by infected body fluids, e.g.

  • Sharing needles with an infected person
  • Blood transfusions with infected blood
  • From mother to fetus across the placenta during pregnancy
  • Mother to baby via breastfeeding
  • Having unprotected sexual intercourse with a person infected with HIV

Controlling the Spread of STIs

• The spread of STIs such as HIV is best controlled by:

  • Not having unprotected sex, but making sure to always use a condom
  • Getting tested if unprotected sex or sex with multiple partners has occurred
  • Raising awareness through education programmes
  • Never sharing needles and ensuring medical equipment is sterile
  • Screening for HIV during pregnancy