HIV is spread by sexual contact or exchange of body fluids such as blood…

The idea

HIV is a virus that infects humans and, if untreated, can lead to AIDS by destroying lymphocytes so the immune system fails. It is not spread by everyday contact such as hugging, sharing food or mosquito bites. Transmission requires direct transfer of infected body fluids into the bloodstream or mucous membranes. This happens during unprotected sexual contact, when drug users share needles and traces of infected blood pass from one person to another, or through blood transfusion and from mother to child. Understanding these routes explains why needle-exchange schemes, condom use and screening donated blood reduce spread. The virus itself does not kill the host directly; it leaves the body unable to fight other pathogens.

What earns the marks

• HIV is a virus that infects lymphocytes and eventually causes AIDS.
• Transmission occurs through sexual contact involving the exchange of body fluids.
• Sharing needles allows infected blood to pass directly between drug users.
• HIV is not spread by casual contact such as touching, sharing cups or insect bites.
• Prevention includes using condoms, not sharing needles and screening blood donations.

Common mistakes and how to put them right

• Saying HIV and AIDS are the same thing.

  Put it right: HIV is the virus, whereas AIDS is the condition that can develop when the immune system is badly damaged.

• Claiming HIV can be caught by hugging or sharing food.

  Put it right: Transmission needs infected body fluids entering the body, not everyday social contact.

• Confusing HIV with a bacterium.

  Put it right: HIV is a virus, so antibiotics do not treat it.

Exam tips

• Name at least two specific routes of transmission rather than writing only that it is spread by body fluids.
• Link each route to a prevention method, such as needle exchange for shared needles.
• Use the terms virus, lymphocytes and immune system accurately to show understanding.