Am I Infected?
(A Guide to Testing for HIV)
Welcome to another day in my life. Today is Saturday and I hope you had a beary safe and great week so far. It is another busy weekend for Dab the AIDS Bear and me.
If you are still HIV negative and are sexually active then you should be going for a HIV test at least every six months. So today and tomorrow I would like to blog about the process of getting a HIV test.
When should you get tested and is the test result accurate?
There is a "window period" which is the time it takes the body to produce antibodies after HIV infection has begun. For the vast majority of those who will test positive, antibodies to HIV will develop within 4-6 weeks after exposure. Some will take a little longer to develop antibodies. To make certain that you receive a reliable test result, it's necessary to wait at least three months (13 weeks) after your last possible exposure to the virus before being tested.
Getting tested before three months may result in an unclear result or a false negative. Some testing centers may recommend testing again at six months. More than 99 percent of those who are going to seroconvert will do so within three months (seroconversion is the development of detectable antibodies to HIV in the blood as a result of infection.) It's extremely rare for seroconversion to take more than six months to develop detectable antibodies.
No diagnostic test will ever be 100 percent reliable, but if you test negative at the appropriate time (i.e., 13 weeks after possible exposure to the virus), you can consider that to be a dependable confirmation that you are HIV negative.
I can't wait 13 weeks to find out! Are there other options?
There are tests that can look for the virus—not antibodies—in the blood. Because the virus becomes detectable in the blood much sooner after infection than antibodies, these tests are an option for people who simply can't wait 13 weeks to find out the results of standard ELISA/EIA and Western blot testing.
These tests look for HIV, either floating around freely in the bloodstream or inside cells in the bloodstream. Some tests—known as qualitative tests—yield a "positive" or "negative" result, meaning that the virus was or wasn't found (GenProbe's Aptima HIV-1 RNA Qualitative Assay is the only test approved for this purpose). Other tests—known as quantitative tests—yield a "viral load" result, meaning the amount of virus in a sample of blood. Roche's quantitative Amplicor HIV Monitor Test is frequently used by doctors and research centers but is not specifically approved for this purpose. It is only approved to monitor to people who are known to be infected with HIV, particularly to find out if their treatment is working properly.
These tests are highly sensitive, meaning that they can detect even the tiniest amounts of HIV in a blood sample. However, they are not always specific, meaning that they can sometimes yield a false-positive result. In turn, follow-up testing using standard ELISAEIA and /Western blot assays, is typically recommended.
Also available are tests that look for both HIV proteins (antigens) and antibodies in a blood sample. One example is Abbott's Architect HIV Ag/AB Combo assay. This particular test can detect HIV up to 20 days earlier than antibody-only tests.
These tests must be ordered by a health care provider, meaning that you should call your doctor if you think you may have recently been exposed to the virus and would like one of these tests. It's also important to keep in mind that some of these tests, notably the qualitative and quantitative assays, can be expensive and are not usually covered by insurance for diagnostic purposes.
Aren't there two different kinds of HIV? How do I know what I should be tested for?
The two known types of HIV are HIV-1 and HIV-2. In the United States and Europe, the overwhelming majority of HIV cases involve HIV-1. HIV-2 infections are predominantly found in West African nations. The first case of HIV-2 was discovered in the United States in 1987. Since then only 79 people with HIV-2 infections have been identified in the United States. While the CDC does not recommend routine screening for HIV-2, when someone tests for HIV-1 using ELISA/Western blot tests, there is a 60 to 90 percent chance that HIV-2 will be detected if it is present.
Not every test will automatically include testing for HIV-2. Anyone who thinks there's a possibility they have been exposed to HIV-2 and/or any of HIV's more rare subtypes should mention this when being tested. Among those for whom HIV-2 testing is indicated are those with sex partners from a country where HIV-2 is prevalent or people with an illness that indicate underlying HIV infection, such as an opportunistic infection, but whose HIV-1 test result was negative.
What about subtypes of HIV?
Thus far, 11 distinct subtypes, also known as "clades" or "genotypes," have been recognized of HIV-1. More than 96% of the HIV-1 infections in the United States and Europe are caused by subtype B. Subtypes B and F predominate in South America and Asia. Subtypes A through H of HIV-1 are found in Africa, along with HIV-2 in sub-Saharan Africa.
The ELISA/Western blot tests can detect antibodies to all HIV-1 subtypes. Viral load tests can also detect and quantify subtypes of HIV-1. The viral load tests can also detect and quantify HIV-2.
Tomorrow I will finish blogging about getting a HIV test. Hope you have a beary safe and great Saturday!
Until we meet again; here's wishing you health, hope, happiness and just enough.
big bear hug,