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Primary infection

Michael Carter, Greta Hughson
Published: 04 March 2016

The first few months following infection with HIV are known as primary HIV infection, or acute HIV infection.

During this initial stage of HIV infection, the immune system is unprepared to attack the virus which therefore reproduces at very high levels. A viral load test at this stage will usually show high levels of HIV in the blood – often higher than at any other stage of HIV infection. For many people, this is accompanied by a dramatic drop in CD4 count.

Diagnosing primary HIV infection

Early HIV infection can cause a range of symptoms, which can be very similar to the flu or other common viral illnesses. These symptoms are sometimes called seroconversion illness, or acute retroviral syndrome. As many as 90% of those diagnosed with HIV will have experienced one or more of the following symptoms, usually within the first four weeks of initial exposure to the virus: fever, rash, headache, feeling generally unwell, aches and pains, mouth ulcers, sore throat, night sweats, weight loss, tiredness, swollen glands, and neurological symptoms like meningitis.

Symptoms typically appear a few days to a few weeks after exposure to HIV and can persists for two to four weeks, although swollen glands may last longer.

Some people do not experience symptoms at all or only for a very short time and it is not possible to diagnose HIV infection without an HIV test.

Although many people with primary HIV infection seek medical care for their symptoms, the diagnosis is often missed due to the similarity with other illnesses. Very few people go to a sexual health clinic with these symptoms and seek an HIV test.

Some doctors believe there may be additional advantages to starting HIV treatment in the first few months after contracting HIV.

However, efforts are underway to increase rates of HIV testing, and people from groups with a high risk of HIV (particularly African people and gay men) should be encouraged to go for an HIV test if they are seen by a GP or other healthcare professional when they have symptoms of primary HIV infection.

HIV testing during this time

After infection with HIV, it may be months before the body generates immune cells that can recognise HIV-infected cells or produces antibodies against HIV. The time at which antibodies to HIV appear is called seroconversion. Before this time, an HIV antibody test will give a negative result.

During suspected primary HIV infection, other forms of test can be used to detect the presence of the virus (or antigen). Such tests respond to a specific protein on the HIV virus, although as HIV becomes fully established in the body the protein will fade to undetectable levels and the test will be inaccurate. Tests that detect the genetic material of HIV itself can identify HIV in the blood within a week of infection and continue to work after seroconversion.

In the UK, most sexual health clinics will use a kit which combines both tests, in order to ensure an accurate result. These are sometimes known as fourth-generation tests.

If you are concerned that you may have recently been at risk of HIV infection, talk to a health professional about HIV testing.

If the risk was in the last 72 hours, you and your doctor should also discuss whether a short-course of preventive HIV treatment called post-exposure prophylaxis (PEP) is appropriate for your situation.

HIV treatment

HIV treatment guidelines recommend that all people with HIV should take HIV treatment. The sooner you start to take HIV treatment, the sooner you can benefit from it.

Moreover, some doctors believe there may be additional advantages to starting HIV treatment in the first few months after contracting HIV. It may have a long-term benefit by helping preserve the body’s natural ability to fight HIV and by limiting the spread of HIV in the body. Treatment will also lower the risk of passing HIV on during a period in which people are unusually infectious (see below).

Your doctor may strongly recommend starting treatment now:

  • If you have an AIDS-defining illness
  • If your nervous system (brain, spine and nerves) are affected by HIV
  • If you have a CD4 cell count below 350
  • If you had an HIV-negative test result less than 12 weeks before being diagnosed with HIV.

If you are in this situation, there may be some pressure to make a decision quickly. Nonetheless you should only start treatment if you feel ready to do so. If you feel that you need time to come to terms with having HIV or to understand what treatment involves, you don’t need to start straightaway.


Because of the extremely high viral load that occurs during the early stages of infection, the risk of transmitting HIV to other people, during unprotected sex for example, may be high during this time

Safer sex, such as using condoms, is particularly important during this time. HIV treatment reduces viral load and reduces infectiousness. If you are concerned about the risk of passing on HIV, this may be another reason to consider taking HIV treatment during primary infection.

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

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.
Community Consensus Statement on Access to HIV Treatment and its Use for Prevention

Together, we can make it happen

We can end HIV soon if people have equal access to HIV drugs as treatment and as PrEP, and have free choice over whether to take them.

Launched today, the Community Consensus Statement is a basic set of principles aimed at making sure that happens.

The Community Consensus Statement is a joint initiative of AVAC, EATG, MSMGF, GNP+, HIV i-Base, the International HIV/AIDS Alliance, ITPC and NAM/aidsmap