Tests performed at clinics or hospitals in Singapore for human immunodeficiency virus (HIV) have three main objectives that follow the standards set by the UNAIDS. The objectives of HIV screening include screening of donated blood, diagnosis of infection in persons, and epidemiological survey or HIV trends and prevalence.
Those are just the general objectives, however, and standards vary among hospitals in Singapore. So, what are your options if you need to undergo HIV screening?
Common Testing Methods
Although there are 100 kinds of HIV tests worldwide and more are still currently in development, there are two main types of HIV screening that look for specific signs. One type of test is the detection of HIV antibodies, which is the most common method in most clinics and hospitals; second is the detection of virus itself.
Antibody tests will look for specific indicators in the blood that your body is trying to fight off HIV. The antibodies are produced by your immune system that can be tested by a HIV test in Singapore and target specific infections like HIV, which can be detected within a 3- to 8-week window period. Enzyme-linked immunosorbent assay (ELISA) is the most popular HIV antibody test, because it is cheap and is suitable for large samples such as blood for blood transfusions.
Testing in Clinics/Hospitals
HIV testing in clinics or hospitals are done to detect the presence of the antigens, the virus, and to determine the stage of the infection. Most doctors recommend either of these two methods: nucleic acid amplification technologies (NAT) or viral culture.
• NAT refers to tests, such as polymerase chain reaction (PCR), that detect the material of HIV. It is used during the treatment of an HIV patient and can detect the virus even if the levels in the sample are very low.
• Viral Culture is the method of growing virus samples from the blood. If the sample can be cultured, it means that your blood is infected with the virus.
You will need at least two different tests to confirm that you are infected with HIV. If your first test resulted in a negative (not infected), a second test is needed within a 3-month window period to confirm the first result.
It’s important to disclose any related information to your doctor regarding your health, lifestyle, sexual history, history of sexually-transmitted diseases (if any), or if you are a victim of sexual assault, so that early treatment can be recommended. The window period (or the time between the initial infection and when it can be accurately detected) varies among individuals, but tests are usually done 3 weeks after the infection and will be repeated within 3 months regardless of the result of the first HIV testing.
Testing in Nonclinical Settings
• Rapid or Simple HIV Tests, also called rapid assays, can be performed in less than 2 hours, but are as accurate as the results of ELISA. These are done using either a filter paper with blood from a pricked finger or a whole blood sample. To date, there are four rapid assays that you can choose from, such as comb or dipstick assays, chromatographic membrane assays, agglutination assays, and flow-through membrane assays.
• Saliva and Urine Tests are additional options, too, because the sample is safer to handle and transport without the risk of infecting anyone. These anonymous HIV test methods can be done at the comfort of your own home with the use of HIV testing kits available in pharmacies in Singapore, and the sample sent to a nearby laboratory.
HIV Testing for Adolescents and Adults
Most doctors recommend that persons aged between 13 and 64 should get an annual HIV testing, especially those who are sexually-active, to avoid possible complications brought about by the virus. It’s not uncommon that some HIV patients were unaware that they were infected until they took HIV tests or experienced some symptoms of the disease.
Some adolescents who were diagnosed with HIV were also victims of sexual assault, that is why it is a standard procedure for hospitals to give victims post-exposure prophylaxis (PEP) right away along with antiretroviral medicines to prevent infection.
HIV infection isn’t just through intimate contact but through contact with infected blood and blood products and mother-to-infant transmission. If you have a history of sexually-transmitted diseases, you are also more likely to get HIV, that is why some doctors might also recommend HIV screening when you’re having your STD tests, which have separate detection methods for each specific infection.
HIV Testing for Pregnant Women
HIV screening for expectant mothers should be included during the earliest routine prenatal check-up and repeated during the 3rd trimester of the pregnancy (or 36 weeks of gestation). This is especially crucial if the woman has a history of STDs or is at high risk for acquiring HIV.
If the woman shows signs of HIV infection, she is recommended to undergo plasma RNA test and HIV antibody test. It is also possible have an HIV screening during labor and immediately postpartum using the rapid HIV test, so that the exposed baby can be given antiretroviral prophylaxis.
HIV Testing for Infants and Children
Children older than 18 months undergo the same tests as those used in adolescents and adults, such as serological testing or the confirmation of HIV antigen and/or antibody presence. The tricky part in testing infants younger than 18 months, however, comes from the manner of transmission from an infected to mother to the child.
The maternal HIV antibody is usually transferred during pregnancy, but the virus declines in his/her first year of life, so the usual tests cannot distinguish the HIV antibody from the infant from the HIV antibody of the mother. If the baby is younger than 18 months and the mother is suspected of having an infection, the assays of the virus and its components are recommended; such as the extraction, amplification, and detection of nucleic acids of the virus; and the detection of RNA to distinguish it from HIV RNA.