Tue | Sep 26, 2017

Testing for HIV - What you need to know about the process and the types of tests available

Published:Wednesday | April 5, 2017 | 4:08 AMJendy McDonald
Blood testing
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Are you considering getting an HIV test done but are worried about the process? It is common to feel a little worried about going to do an HIV test, but the decision to do the test is the best thing you can do for your health. The process is painless, quick, confidential and almost always free.

Prior to taking the test, the health-care professional will speak to you about your sexual health and any risks you may have taken. The health-care professional is your friend and will not judge you but assist you. There is most likely nothing you can say that they haven't heard from someone else. Be honest with them, and ask as many questions as you want, this is the reason they are there. However, you should not feel pressured to take the test! The results will be completely confidential, so you should only go through with it if you want to.

HIV tests may be performed on blood, oral fluid, or urine. The testing process is simple! Normally, testing involves taking a small sample of blood from either your finger or your arm, or a sample of oral fluid.

There are three broad types of tests available: Antibody tests, NAT (nucleic acid test), and a combination test that detects both antibodies and viral protein called p24. Different tests can be used to see if a person is HIV-positive, the two most common of which are explained below. One of the tests looks for the presence of the virus and the other for HIV antibodies.

HIV ANTIBODY TESTS

If you go for a testing in a government or public health clinic, HIV antibody tests are most commonly used, as they are the cheapest. The two most common HIV antibody tests will be explained: the rapid test and ELISA.

ELISA: The ELISA test was first developed in 1985, and has been drastically improved over time; and nowadays a third-generation or fourth-generation ELISA can be used.

- Third-generation HIV tests (ELISA antibody): When you become infected with HIV, your body will start to produce specific antibodies (proteins attached to the virus to try and destroy it). An HIV antibody test looks for the presence of these antibodies in your blood, saliva or urine. If these antibodies are found, it means you are infected with HIV. This test is only accurate after three months, because this is how long it takes your body to produce enough antibodies for it to show up in a test.

- Fourth generation HIV tests (ELISA combined antigen/antibody): A combination, or fourth-generation, test looks for both HIV antibodies and something called P24 antigens. Antigens are foreign substances that cause your immune system to activate. The antigen is part of the virus itself and you have a lot of these in your blood in the first few weeks after infection. This is why you are most infectious to others in this period too. Fourth-generation tests can detect HIV from 11 days to one month after you have been infected.

NAT: A nucleic acid test (NAT) looks for HIV in the blood. It looks for the virus and not the antibodies to the virus. The test can give either a positive/negative result or an actual amount of virus present in the blood. This test is very expensive and not routinely used for screening individuals unless they recently had a high-risk exposure or a possible exposure with early symptoms of HIV infection.

It can take seven to 28 days for a NAT to detect HIV. Nucleic acid testing is usually considered accurate during the early stages of infection. However, it is best to get an antibody or combination test at the same time to help the doctor interpret the negative NAT.

Recent developments have made both of these tests accurate and trustworthy. However, false positives are still possible and any positive test should always be confirmed by a second test, using a different method or brand. Different countries have different protocols for HIV testing.

THE WINDOW PERIOD

What is the window period? The period from which a person is infected until the antibodies have been manufactured is called the window period. During the window period, antibodies are still being formed but are not present in high enough amounts to measure. A person, therefore, tests negative even though the virus is already in the blood. Usually these antibodies form within two to six weeks, but sometimes it can take as long as three months.

The window period sometimes causes a lot of confusion. Here's an example: Let's say someone had unprotected sex on Saturday night. On Monday, he goes to get an HIV test. The test will almost certainly come back negative, even if he was infected with HIV on Saturday night, because his body has not yet had a chance to make antibodies. Even if he went for a standard antibody-based HIV test one or two months later, he might still get a negative result even if he had been infected on that Saturday night. Again, the reason is because he has not yet produced antibodies, which are what the HIV test is looking for.

Talk to your health-care provider to see what type of HIV test is right for you. If you are worried about something that happened that may have exposed you to HIV, you naturally will want to get tested as soon as possible. A good strategy would be to go back for a test three months after your possible exposure. The result you get after three months will be 99 per cent certain. However, if you think you may have been exposed to HIV and are having symptoms of HIV infection, see a provider right away. The provider may be able to perform one of the tests that detect the virus directly.

HOME TESTING

Some persons may decide to do home testing instead. Currently, there are only two home HIV tests: the Home Access HIV-1 Test System and the OraQuick In-home HIV test. If you decide to test for HIV in your home, make sure that the testing kit you are using is made specifically for self-testing and that it has a 'CE' mark on it (UK), or it is FDA-approved (USA). That way, you'll know that the tests are regulated and work properly. It is also very important that you follow the instructions on your HIV testing kit. If you have any questions about self-testing, speak to a health-care professional.

The OraQuick HIV Test, which involves taking an oral swab, provides fast results. You have to swab your mouth for an oral fluid sample and use a kit to test it. Results are available in 20 minutes. The manufacturer provides confidential counselling and referral to follow-up testing sites. Because the level of antibody in oral fluid is lower than it is in blood, blood tests find infection sooner after exposure than oral fluid tests. These tests are available for purchase in stores and online. They may be used at home, or they may be used for testing in some community and clinic testing programmes.

The Home Access HIV-1 Test System is a home collection kit, which involves pricking your finger to collect a blood sample, sending the sample by mail to a licensed laboratory, and then calling in for results as early as the next business day. This test is anonymous. The manufacturer provides confidential counselling and referral to treatment. If you use any type of antibody test and have a positive result, you will need to take a follow-up test to confirm your results. If your first test is a rapid home test and it's positive, you will be sent to a health-care provider to get follow-up testing. If your first test is done in a testing lab and it's positive, the lab will conduct the follow-up testing, usually on the same blood sample as the first test.

After you get tested, it's important for you to find out the result of your test so that you can talk to your health-care provider about treatment options if you're HIV-positive. If you're HIV-negative, continue to take actions to prevent HIV, like using condoms the right way every time you have sex and taking medicines to prevent HIV if you're at high risk.

To get an HIV test done, you may visit one of the health-care clinics, hospitals or sexual health clinics in your area. Remember! HIV is preventable and manageable.

- Jendy McDonald is an AIDS educator with Positive Impact Ministries and a 'Channel of Hope' facilitator with AIDS Link International, South Africa. Email: positiveimpactministries1@gmail.com; yourhealth@gleanerjm.com