Stages of HIV infection

Some people have a short flu-like illness soon after infection, called a ‘seroconversion illness’ because it coincides with the period during which the body first produces antibodies to HIV. Common symptoms include a high temperature (fever), sore throat, a blotchy rash on the body, tiredness, swollen glands, joint and muscle pain.  

The severity of symptoms at this stage can vary considerably between people – they can be so mild as to go unnoticed or so severe that admission to hospital is required.

This early stage of HIV infection is also sometimes called primary HIV infection or acute HIV infection. During this time, you will have a lot of HIV in your body (a high viral load) and this means the risk of passing HIV on is higher than at other times.

Once someone has passed through the primary infection phase, they usually recover from any symptoms and enter a phase of infection in which they don’t experience any symptoms. Any effects HIV is having on the immune system don’t cause outward signs or symptoms. For this reason, this period is sometimes called ‘asymptomatic HIV infection’ and it can last for several years.

But even if you are feeling well, HIV is damaging your immune system. Doctors use two key laboratory tests to see how active HIV is and what impact it is having on your immune system. These tests are a CD4 cell count, which gives a rough indication of the strength of the immune system, and an HIV viral load test, which shows how active HIV is in the body. Both these tests are discussed in a lot more detail in the sectionKey tests to monitor HIV – CD4 and viral load.

The results of these tests are important for you and your doctor in making decisions about when to start HIV treatment. In the UK, treatment guidelines recommend you start treatment when your CD4 cell count is around 350 cells/mm³.

Over time, your CD4 cell count will fall, which is a sign that your immune system is being weakened. The longer you live with HIV without treatment, the greater your risk of developing symptoms.

If you have certain serious infections or cancers which have been confirmed by tests, then you will be diagnosed as having AIDS. In the US, if your CD4 cell count falls to below 200, the level at which you become vulnerable to serious infections, you are also diagnosed as having AIDS.

The way HIV disease progression is often described suggests that there is an inevitable, one-way course in HIV infection. It implies that everybody with HIV will be initially well, then have abnormal CD4 tests before becoming ill with minor illnesses, and finally go on to develop severe and fatal illness.

However, with care and treatment, your immune system can be protected, or can recover. If you are diagnosed with a low CD4 count and start taking HIV treatment, your CD4 count can rise. If you start treatment at the time recommended, your CD4 count need not fall to levels where you are at risk of developing serious illnesses because of HIV.