What are the Types of HIV Tests that Doctors May Recommend?

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Medical Video: Insidermedicine In Depth - July 20, 2010 - False Positive HIV Tests

HIV testing is done to diagnose people who have recently been infected with the virus. In addition, HIV testing is also done to detect previously unknown infections and at the same time to ascertain HIV status in people at risk of HIV. Couples who want to get married should also consider taking an HIV test. This is done to tell how to prevent HIV. Then what types of HIV testing can be done? Here's the explanation.

Who needs HIV testing?

Based on the Minister of Health Regulation, there are several indications of HIV testing, namely:

  • Every adult, child, and adolescent with a medical condition that is suspected to have HIV infection. Especially with a history of tuberculosis (TB) and venereal disease.
  • Antenatal care for pregnant women and mothers.
  • Adult men who request circumcision as an HIV prevention measure.

Infants and children with the following conditions also need an HIV test. These conditions include:

  • Children have HIV-related illnesses such as severe TB or receive recurrent anti-tuberculosis (OAT), malnutrition, or recurrent pneumonia and chronic or recurrent diarrhea.
  • Newborns from mothers infected with HIV and have taken preventive measures for transmission from mother to child.
  • Children whose family history is unknown.
  • Exposed or potentially having HIV infection through contaminated needles, receiving repeated transfusions, and other causes.
  • Children who experience sexual violence.

In addition, HIV testing must also be offered routinely to:

  • Sex workers, injecting drug users (IDUs), men having sexual relations with men (MSM), and transvestites. The test must be repeated at least every 6 months.
  • Couples of PLWHA.
  • Pregnant women in widespread epidemic areas and concentrated epidemics.
  • TB patients.
  • Everyone visiting health care facilities in the HIV epidemic area is expanding.
  • Patients with venereal disease.
  • Hepatitis patient.
  • Prisoners.

how to transmit HIV

Type of HIV test

1. Serology test

Serology tests consist of:

Fast test

Rapid tests with reagents that have been evaluated by the institution appointed by the Ministry of Health can detect both antibodies to HIV-1 and HIV-2.

Rapid tests can be run on fewer samples and the waiting time to find results is less than 20 minutes, depending on the type of test and must be done by trained medical personnel.

ELISA test

This HIV test detects antibodies for HIV-1 and HIV-2 carried out by ELISA (enzyme-linked immunisorbent assay) or also known as EIA (enzyme immunoassay). 

Antibodies are proteins produced by the immune system in response to the presence of foreign substances, such as viruses. If your HIV test on an ELISA is positive, your doctor will recommend a follow-up test with Western bolt to confirm HIV infection.

Blood samples are taken from the surface of your skin, with a blood collection procedure in general. Then the blood sample is inserted into a special tube. Blood samples are sent to the laboratory for analysis. For the ELISA test, a blood sample is inserted into a petri dish containing HIV antigens. Antigens are foreign substances, such as viruses, which cause the body's immune system to respond.

If your blood contains antibodies to HIV, blood will bind to the antigen. Then this will be examined by adding an enzyme to the petri dish, to help speed up the chemical reaction.

After that, you will see how your blood and antigen react. If the contents of the petri dish change color, you may be infected with HIV.

The results of an ELISA HIV test usually take one to three days, but this varies depending on the test, the laboratory, and whether it is a home health test.

Because there is a small chance that a person's antibodies will stick to non-HIV proteins during the test, a second, more specific test is needed. However, this second test is done if the test is initially positive.This test is called Western blot.

Western blot test

This HIV test is an antibody test for confirmation in difficult cases.In this test, HIV proteins are separated by size and electric charge, as well as serum coated on the test strip.

If this test shows a positive result, a series of ribbons (the band) detected which indicates a specific binding of a person's antibodies to certain HIV virus proteins. This test is only done to follow up on a initially positive screening test. This is not helpful if done alone.

If an HIV test shows positive on the ELISA test, you might get HIV. However, sometimes there are false positive with an ELISA screen. This means that the test results show that you have HIV, when in fact you don't.

Therefore, a further test is needed, namely the Western blot test to determine whether you are truly infected with the HIV virus. Usually this happens if you have a condition such as Lyme disease, syphilis, or lupus.

The Western blot test only requires one day to do, but some laboratories may not do tests every day.

Sometimes, HIV does not appear on an ELISA test even if you are infected. This can happen if someone is in the early stages of infection, and their body has not produced enough antibodies for the test detected.

The initial stage of HIV infection, where someone is infected with HIV, but the test results show negative, this is known as the "window period".

According to Centers for Disease Control and Prevention (CDC), a person's window period is usually between 3 and 12 weeks. However, in rare cases, some people can take six months to develop antibodies.

2. Virological testing with PCR

Virological tests are carried out by method polymerase chain reaction (PCR). A virological test is important to check for HIV-positive pregnant women who have just given birth or newborns. Babies who are known to be exposed to HIV from birth are advised to check with the earliest virological test at six weeks of age.

In addition, this HIV test is recommended for diagnosing children aged less than 18 months.

This test may also help in detecting HIV infection in the first four weeks after exposure, before the antibodies have time to develop.

If the baby with the first virological examination is positive, then antiretroviral therapy (ART) must be started immediately, at the same time a second blood sample is taken for the second virological test.

Recommended virological tests are:

Qualitative HIV DNA (EID)

Qualitative DNA testing of HIV from complete blood orDried Blood Spot(DBS). This HIV test detects the presence of viruses and does not depend on the presence of HIV antibodies. This test is used for diagnosis in infants.

Quantitative HIV RNA

Quantitative HIV RNA test using blood plasma. This HIV test is done to check the amount of virus in the blood (viral load) and can be used for monitoring ART therapy in adults and diagnosis in infants if HIV DNA is not available.

ART therapy is carried out to make the viral load decrease, ideally up to undetectable levels.

The method of testing HIV with PCR is done with the help of an enzyme to double the HIV virus in the blood. Then the chemical reaction will mark the virus. This marker is ribbon-shaped (the band) which is measured and used to count the number of viruses. The results of RNA testing usually take several days to a week.

In general, your viral load will be declared "undetectable" if it is under 40 to 75 copies in your blood sample. The exact lift will depend on the lab that analyzes your test. When your viral load is high, you have more HIV in your body, and that means your immune system fails to fight HIV properly.

Although this test can be said to be the most accurate, this test is not done as often as other HIV tests because the price is quite expensive.

3. HIV antibody tests

An Ab-Ag HIV test detects antibodies directed against HIV-1 or HIV-2, as well as a protein called p24, which is part of the virus core (antigen from a virus). This is important because it takes weeks for antibodies to form after the initial infection, even though the virus (and p24 protein) is in the blood. As such, Ab-Ag testing allows early detection of HIV infection.

A study showed that a diagnosis can be made on average one week before using the Ab-Ag test, compared with antibody testing alone. The test uses a reaction known as "chemiluminescence" to detect antibodies and p24 protein antigens. In other words, if there are antibodies or antigens, the test reaction emits light that appears on the detector. There is only one antibody-antigen test currently approved, the HIV Architect Test Ag / Ab Combo. If this test is positive, the doctor will recommend doing a second test with Western blot.

What are the Types of HIV Tests that Doctors May Recommend?
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