HIV (the human immunodeficiency virus) weakens your immune system. When you first become HIV positive, you might not feel ill or even know you have HIV. Once you have been diagnosed with HIV, the health of your immune system should be regularly monitored by your HIV clinic. This will be done by looking at your CD4 cell count (a type of immune system cell). You can find out more about CD4 cell counts and other tests your clinic will use to monitor your health in NAM’s information booklet CD4, viral load & other tests.

HIV treatment is also called antiretroviral therapy (ART) and is recommended for all people living with HIV. HIV treatment you take now will protect your health, both now and in the future. HIV treatment lowers the level of HIV in your body and allows your immune system to build up and stay strong. The aim of HIV treatment is to reduce your viral load to below the level at which most tests can detect HIV – usually under 50 copies/ml. This is often referred to as an ‘undetectable’ viral load because the most commonly used viral load tests can’t detect such small quantities of virus. Having an undetectable viral load means that HIV is still in your body, but at very, very low levels. (There are now some ultra-sensitive tests that can measure below 20 copies/ml.)

By strengthening your immune system, HIV treatment helps prevent you from developing certain illnesses, such as some serious infections and types of cancer. Some of these illnesses, known as AIDS-defining illnesses, only happen when HIV has progressed and your immune system has been weakened, AIDS stands for: 

Acquired – something you get

Immune – the system in your body that usually protects you against illness

Deficiency – weakens your immune system

Syndrome – a collection of illnesses.

So AIDS refers to a range of illnesses people may get when HIV has weakened the immune system so much that it cannot protect them.

With the right treatment and care, many people with HIV may never experience AIDS. Taking your HIV treatment in the right way and at the right time (called ‘adherence’) is the most important factor in preventing it. Other things, including lifestyle factors such as diet, exercise and smoking, can also influence your health.