HIV

HIV

The standard blood test for HIV is negative in persons with acute HIV infection, so a special blood test has to be used if this diagnosis is suspected.

There are two tests to diagnose acute HIV infection:

• HIV viral load

• HIV p24 antigen test (both available through health care professionals)

Tests should be carried out:

On persons who have had a known exposure to the infection through:

• sharing needles

• unprotected sex

and on persons

• who have symptoms of acute HIV infection

Standard blood test becomes positive about 4-6 weeks after infection. HIV is mainly detected by testing a blood sample for the:

• presence of antibodies (disease-fighting proteins) to HIV

HIV antibodies generally do not reach detectable levels until 1-3 months following infection, sometimes taking up to 6 months to be generated in large enough quantities to show up in standard blood tests

HIV testing is also carried out on samples of:

• saliva

• urine

Early testing for HIV infection should be carried out as soon as antibodies to the virus develop to enable:

• Appropriate treatment to be received when they are most able to combat HIV

• The emergence of certain opportunistic infections to be prevented

• HIV-infected people to be alerted

• High-risk behaviors that could spread HIV to others to be avoided

HIV testing and counselling are available in most doctors' offices or health clinics. Individuals can be tested anonymously at many sites if they have particular concerns about confidentiality. In addition, blood samples for anonymous HIV testing may now be collected at home. Home-based test kits are available by telephone order or over the counter at pharmacies.

Two different types of antibody tests are used to diagnose HIV infection:

• ELISA

• Western Blot

If a person is highly likely to be infected with HIV and yet both tests are negative, a doctor may test for the presence of HIV itself in the blood, with a repeat antibody testing at a later date, when antibodies to HIV are more likely to have developed.