HIV testing is a diagnostic procedure used to detect the presence of Human Immunodeficiency Virus (HIV) or antibodies produced in response to HIV infection. The test determines whether there is a virus present in the blood, usually by detecting T-cells that have been attacked by HIV and damaged. It can also detect the actual virus (viral load).
The main purpose of HIV testing in Singapore as is other regions is to diagnose an individual with HIV before it has caused any symptoms. A positive result indicates that the individual has contracted the virus; this diagnosis would require further investigation, including CD4 cell count and viral load tests, which are performed on patients diagnosed with AIDS.
The Types of HIV Tests Available
There are basically three types of HIV tests but the mostly used ones are the antibody and antigen/viral load. An antigen test is a diagnostic procedure that detects the presence of HIV proteins using an enzyme-linked immunosorbent assay (ELISA).
It forms part of the initial ELISA series, which may vary depending on how recent exposure to HIV was suspected. The results can take up to 3 weeks for final determination if hepatitis B (core antibody) is present in addition to HIV 1 and 2 antibodies; however, if only HIV antibodies are detected, the result should be available within less than one week.
The second type of antigen test called a western blot, or WB test, may also follow positive ELISA tests and help determine which strains of the virus (HIV-1 or HIV-2) the person has been exposed to. The antigen/viral load test is also known as PCR (polymerase chain reaction).
It detects the presence of viral RNA using nucleic acid amplification and is performed on samples such as plasma, saliva, or urine. The result can be determined within a few hours after collection.
A big advantage of an antigen/viral load test over ELISA tests is that it distinguishes between different strains of the virus and allows for adequate treatment. An ELISA test may give false-negative results if too many antibodies are present in the sample, thus masking the presence of HIV; additionally, if a person is tested too early, an ELISA test may also give false negative results since HIV antibodies do not form for up to three months after infection.
An ELISA test has disadvantages as well. It only detects the presence of HIV antibodies and does not detect the virus itself; therefore, it can produce false-positive results by reacting with antibodies produced against other diseases such as tuberculosis (TB) or hepatitis C (HCV); this is called cross-reactivity or false positive testing. For this reason, it is important that any initial ELISA tests are followed up immediately with additional tests to confirm whether the first result was correct or not.
It should be noted that an antibody test cannot determine whether the individual ever had the disease but only if the individual has contracted HIV within weeks or months of being tested. If you are planning for HIV testing in Singapore, it is advisable that you have just one HIV test using different methods of detection so as not to complicate matters further since there are slight variations in accuracy depending on the type of test used.
How Accurate are HIV Tests?
HIV tests are between 99% and 100% reliable. This means that if an HIV-positive person takes an HIV test, the test will correctly identify them as being HIV-positive 99% to 100% of the time. If an HIV-negative person takes an HIV test, the test will correctly identify them as HIV-negative 99% to 100% of the time.
There are a very small number of cases where the test will give a false result. If this occurs, it is usually because the person being tested has been recently infected with HIV, and there are still high levels of antibodies to HIV in their blood, but no virus has yet been made; therefore, an antigen/viral load test would be necessary to confirm recent infection.
If you took an antibody test (or ELISA) and were told that you are HIV-positive, you should seek confirmation through other means since all antibody tests have a small chance of producing false results; if you were told that you are HIV-negative, an antigen/viral load or western blot should be used to screen for recent infection (within three months). You can then use this result to confirm that you are HIV-negative because antigen/viral load tests have a high level of accuracy.
When should you get an HIV Test
The Centers for Disease Control and Prevention (CDC) recommends that all adults aged between 13 to 64 years should be tested at least once in their lifetime. People who have a known exposure to HIV, such as sex without a condom with someone whose status is unknown or intravenous drug use, should consider being tested every three to six months. Pregnant women should also take an HIV test so the risk of passing on the virus during childbirth can be managed effectively.
Individuals from high-risk groups such as men who have sex with other men or female prostitutes are at increased risk of contracting HIV, and hence all these individuals should be tested regularly for HIV whether they experience symptoms or not. Early detection will ensure a better prognosis.
What should you do if your HIV Test Results turn out Positive?
If you undergo HIV testing in Singapore and the result is positive, you should seek immediate medical attention. Clinicians will be able to advise you on treatment and management of the virus as well as counseling options.
There are over 30 antiretroviral drugs available that can be used for treatment; these drugs cannot cure the infection, but they can slow down the spread of the virus in your body, which means you live longer and have a better quality of life. It is important to note that there is no vaccine against HIV, and there is no cure for AIDS yet, so early detection coupled with effective treatment will significantly improve the prognosis.
The Bottom Line
The chances of a person taking an HIV test and getting a false result are very small; if you have been told that your results are inconclusive, you should seek advice from another qualified physician as soon as possible.
At The Health Advisory Clinic, we offer confidential testing for sexually transmitted infections, including HIV. We also have a team of clinicians who can provide counseling and treatment services to those who test positive. Please call us on (+65) 6226 6442 or WhatsApp: (+65) 9886 6442 to book your appointment.
The Health Advisory Clinic – Women’s Health | STD/HIV Testing
1 Raffles Pl, #04-49, Singapore 048616
+65 9886 6442