HIV is one of the world’s most notorious infections. With an estimated 33.1 million people having the infection across the world, it’s also one of the most virulent. Human immune deficiency virus,or HIV, is the virus that causes Acquired Immune Deficiency Syndrome (AIDS).
The HIV virus attacks the immune system and reduces the body’s ability to fight other diseases such as cancer, pneumonia and tuberculosis. It isn’t the HIV virus, or AIDS that kills, it’s these other infections that do that. HIV just opens the door for them.
There is currently no cure for HIV, but treatments are available to suppress it. This provides valuable time before the body is eventually overcome. That makes education and prevention of the disease vital in the battle to beat it.
HIV testing takes many forms.Initial diagnosis testing includesantibody testing, P24 antigen tests and a PCR test. Once diagnosis has been confirmed, further testing may be necessary, such as CD4 test and the viral load test.
To determine if someone is infected with HIV, an antibody test is usually performed. This is an enzyme-linked immunosorbent test, or ELISA for short. They are also known as enzyme immunoassay tests, (EIA).
These tests look for antibodies that are generated when the body responds to the HIV infection. Antibodies are released by the immune system to fight the virus, and these tests are designed to detect them. The specific antibodies are unique to HIV, which is why these tests work.
Most people will develop these antibodies 6 to 12 weeks after infection. That means, those being tested have to wait three months before taking the test. If the test is negative, it’s a reasonable indicator that the person does not have HIV.
If infection is still suspected, a further test at 6 months is undertaken. If there has been no further risk of infection since the first test, a negative test here will confirm the lack of infection.
Antibody testing is extremely accurate. ELISA tests are sensitive enough to detect even the smallest number of HIV antibodies. False positive results are possible, which is why an initial test will result in a confirmation test, just to make sure.
If an antibody test detects that HIV antibodies are present, a confirmation test is necessary. There are four types of confirmation test, the Western blot assay, indirect immunofluorescence assay, line immunoassay and a second ELISA.
The Western blot has been around since the earliest days of HIV testing. It can be difficult to administer, but provides accurate results for antibodies.
The indirect immunofluorescence assay uses a microscope to detect HIV antibodies. The line immunoassay is similar, but rarely used here, mainly in Europe. It is as accurate as the Western blot. The second ELISA test will use a different test kit, from a different brand with a different method to confirm presence of antibodies.
When the two tests, initial and confirmation, are combined, the chance of getting an inaccurate result is less than 0.1 percent.
P24 Antigen Testing
Antigens are particles that are carried with a virus that can be detected in the blood. In the case of HIV, the antibody released in response is a protein called P24. The protein is released in great numbers, which makes its presence relatively easy to detect.
The detection window for the P24 antigen test is limited, as the protein fades as HIV takes hold. It is now mostly used in conjunction with other tests called “fourth generation testing.” The P24 antigen test is combined with a standard antibody test which provides very reliable results.
Fourth generation tests have been standard in Europe for some time, and the FDA approved its use here in June 2010.
A Polymerase Chain Reaction test (PCR) relies on the detection of the genetic material within the HIV cell to provide a result. This test allows much earlier detection, usually two to three weeks after infection. The PCR test is also referred to as a viral load test.
It is PCR testing that is used in blood banks and other transfusion centers to test for the presence of HIV before making the blood available. It’s also the test used on babies born to HIV-infected mothers. Babies can carry the antibodies for HIV for several months after birth, but not necessarily the virus itself.
PCR tests aren’t usually provided for individuals as they are expensive and much more complicated to deliver. Obtaining results from a sample takes a lot of work, and needs expert interpretation before results can be provided.
It is possible to test for HIV at home. There is currently only one manufacturer in the country with FDA approval, although there are many more selling the tests online.
Samples are provided at home, then the kit sent to a laboratory. Results are usually available a few days later. The advantages of privacy and anonymity, plus the speed of response is making these kits very popular.
Home testing kits are antibody tests using either blood or saliva. They are quite accurate, but will still need a professionally administered confirmatory test in the event of a positive result.
Currently, there is no FDA approval for home test kits that generate their own results. These types of tests are illegal in many countries and cannot guarantee accuracy. It’s important to have professional testing of any sample to provide an accurate result.
Anyone who thinks they have been exposed to HIV should have a test. Gone are the days when testing was taboo, or frowned upon. Gone are the days when you were identified and had to declare it to insurance companies. Many testing facilities offer anonymous testing facilities for those who value their privacy.
The accuracy of modern testing, and the relative speed at which results are made available have made HIV testing much more manageable.
HIV testing is now available at most clinics, doctors surgeries, hospitals and specialist HIV and AIDS outreach centers of clinic sites. They will usually include a discussion with a professional and counseling as part of the service, especially if the results are positive.