Stages of HIV infection

Seroconversion and primary 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.

Generally, people won't need HIV treatment at this stage of HIV infection, but there are some exceptions to this.

Chronic HIV infection

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 symptoms or ill health. This does not mean HIV is not having an effect on your immune system, just that there are no outward signs or symptoms. For this reason, this period is sometimes called ‘asymptomatic HIV infection’ and it can last for several years.

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 section Key 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.

HIV infection with symptoms

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 two or more serious, HIV-linked infections or cancers, which have been confirmed by tests, then you may 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.

AIDS

If HIV isn't treated, the gradual weakening of the immune system it causes leaves the body vulnerable to serious infections and cancers which it would normally be able to fight off. These are sometimes called ‘opportunistic infections’ because they take the opportunity of the body’s weakened immunity.

If you develop certain opportunistic infections, you may be diagnosed as having AIDS. AIDS stands for acquired immune deficiency syndrome. People diagnosed as having AIDS may become unwell with different illnesses, depending on the opportunistic infections they develop. This is why AIDS is not considered a disease, but a syndrome – a collection of different signs and symptoms, all caused by the same virus, HIV.

AIDS is just a term that doctors and researchers sometimes find useful. You may also hear the term ‘late-stage HIV’ used to mean the same thing. If someone develops an AIDS-defining illness this doesn't mean they are on a one-way path to illness and death. With the right treatment and care, many people who have been diagnosed as having AIDS recover from their AIDS-related illness and go on to live long and healthy lives.

Nowadays, with effective HIV treatment, many people with HIV will never develop AIDS.

More than a definition

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 never fall to levels where you are at risk of developing serious illnesses because of HIV.

Contact NAM to find out more about the scientific research and information used to produce this section.

This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.