HIV and AIDS

The human immunodeficiency virus (HIV) is a retrovirus that infects cells of the human immune system, particularly the CD4 T helper lymphocytes that coordinate immune defences. Over time, untreated HIV infection destroys these cells, weakening the body's ability to fight off infections and certain cancers. The most advanced stage of the infection is known as acquired immunodeficiency syndrome (AIDS), defined by a severely depleted immune system and the appearance of opportunistic illnesses.

As a retrovirus, HIV carries its genetic material as RNA and uses an enzyme called reverse transcriptase to convert that RNA into DNA, which is then integrated into the host cell's genome. This integrated form allows the virus to persist for the life of the infected cell. HIV is transmitted through certain body fluids, including blood, semen, vaginal fluids and breast milk, commonly through unprotected sexual contact, sharing of contaminated needles, or from mother to child during pregnancy, birth or breastfeeding. It is not spread by casual contact such as shaking hands or sharing food.

There is no cure that eliminates HIV from the body, but antiretroviral therapy can suppress the virus to very low levels, allowing people with the infection to live long, healthy lives and greatly reducing the risk of transmission. Diagnosis relies on blood tests that detect HIV antibodies or viral components. Research into preventive vaccines continues, while prevention currently centres on safer practices, testing and medication.

Frequently asked questions

What is the difference between HIV and AIDS?

HIV is the virus that causes the infection, while AIDS is the late stage that develops when the immune system has been severely damaged by untreated HIV.

How is HIV transmitted?

It spreads mainly through blood, sexual fluids and breast milk, by routes such as unprotected sex, shared needles or mother-to-child transmission. It is not spread by ordinary casual contact.

Can HIV infection be treated?

Yes. Antiretroviral therapy suppresses the virus, preserves immune function and reduces transmission, though it does not remove the virus from the body entirely.