What HIV does to the body

Overview
 Stages of HIV infection
Becoming HIV antibody positive
Seroconversion illness
Asymptomatic HIV infection
 Symptomatic HIV infection
An AIDS diagnosis

Overview

The Human Immunodeficiency Virus (HIV) damages the body’s immune system by targeting a type of white blood cell known as a CD4. Viruses copy their genetic code into the nucleus of CD4 cells so that they begin to manufacture HIV viruses instead of functioning as part of the immune system.

Over time, an HIV positive person’s immune system is gradually weakened as their viral load increases and their CD4 count decreases. The progress of HIV infection is measured by regularly monitoring these two indicators.

Left undiagnosed and untreated, HIV infection eventually leads to an AIDS diagnosis. This process may take anything from just a couple of years to decades. Acquired Immune Deficiency Syndrome (AIDS) is usually diagnosed when the patient is found to have one or more ’AIDS defining illnesses’ and their CD4 count has dropped below a particular level.

Although some typical patterns of HIV infection have been identified, the virus impacts each person differently. This is in part due to a number of variables such as age, gender, and genetic or environmental factors.

As the immune system is progressively damaged by HIV, the way is left open for ’opportunistic infections’ to take hold. These infections would normally be held at bay by a healthy immune system, but with few defences left an HIV positive person is increasingly vulnerable to this type of condition. Research has now shown that incidences of opportunistic infections decline when the patient is taking antiretroviral treatment.

Stages of HIV infection

  • Becoming HIV antibody positive
  • Seroconversion illness
  • Asymptomatic HIV infection
  • Symptomatic HIV infection
  • An AIDS diagnosis

Becoming HIV antibody positive

Primary HIV infection is the period immediately after an individual has been infected with HIV and before they have produced sufficient antibodies to reduce significantly viral load and stabilise their condition. Most people who become infected with HIV do not notice that they have been infected. A very high viral load develops about five days after infection. Symptoms, when they occur, develop about ten days after infection. Studies are now suggesting that between 30 and 50 per cent of HIV transmissions are from people who are themselves infected in the previous six months.

Usually HIV is detected by an HIV antibody test. The amount of time between acquiring HIV infection and developing antibodies varies. The vast majority of people with HIV will produce antibodies by around 45 days after infection. However, in a small proportion, it may take up to six months for antibodies to develop, and in a very few people with HIV infection it may take even longer. This is one reason why a lack of HIV antibodies does not always mean freedom from infection.

Seroconversion illness

Before the appearance of antibodies to HIV in the blood, some people may develop symptoms following exposure to HIV. This is known as Seroconversion illness. The symptoms may include:

  • Prolonged fever (4-14 days) and aching limbs
  • Red blotchy rash over the trunk
  • Sore throat (pharyngitis)
  • Ulceration of the mouth or genitals
  • Diarrhoea
  • Sever headaches
  • Aversion to the light

Symptoms of Seroconversion may occur in up to 80% of people infected, but the severity of the symptoms varies. Some people report only a mild flu-like illness 2-6 weeks after risk of HIV exposure, but others experience an illness severe enough to require hospitalisation.

Remember that these symptoms could be caused by other infections: flu, glandular fever, tonsillitis and a serious herpes attack have similar symptoms to those reported in Seroconversion illness.

Asymptomatic HIV infection

In the initial stages of infection damage caused by HIV has no outward effect. This is called asymptomatic infection and it may last for many months or years.

People who have HIV can feel perfectly well. Nevertheless blood tests will show how HIV is affecting the body. It is important for HIV positive people to have two blood tests done regularly.

The first is called the CD4 count. This is a measure of the strength of the immune system. The lower the count, the greater to the damage to the immune system.

The second is the viral load test. This is a measure of how actively the virus is replicating in the body. It measures the number of copies of HIV in a sample of blood. The lower it is, the better.

Symptomatic HIV infection

Without treatment, statistical studies show that the more time passes, the more likely it is that the damage to the immune system will become more severe and infections or tumours may develop. However everyone is different and will have a different response to HIV.

Infections that our immune system normally fights off may develop. These are called opportunistic infections. In the same way, cells, which are normally kept under control by a healthy immune system, may cause opportunistic tumours or sometimes cancers.

HIV can also have direct effects upon the body. For instance the virus can also attack immune cells in the brain. These cells are involved in feeding the brain cells. If they are damaged, it may lead to HIV-associated dementia.

AIDS diagnosis 

There is no single test for AIDS. Doctors look at a variety of symptoms and tests before coming to a diagnosis. They will look for one of the opportunistic infections or cancers in the presence of underlying immune deficiency.

These tests are normally only available if the patient has already been diagnosed as HIV antibody positive, or sometimes if they are seriously ill.

Last updated April 2010

What HIV does to the body