Hiv Tests For Screening And Diagnosis
HIV tests are very accurate, but no test can detect the virus immediately after infection. How soon a test can detect HIV depends upon different factors, including the type of test being used. There are three types of HIV diagnostic tests: nucleic acid tests , antigen/antibody tests, and antibody tests.
An initial HIV test usually will either be an antigen/antibody test or an antibody test. If the initial HIV test is a rapid test or a self-test and it is positive, the individual should go to a health care provider to get follow-up testing. If the initial HIV test is a laboratory test and it is positive, the laboratory will usually conduct follow-up testing on the same blood sample as the initial test. Although HIV tests are generally very accurate, follow-up testing allows the health care provider to be sure the diagnosis is right.
Resources for FDA-approved laboratory tests, self-tests, and testing of self-collected samples are available. Learn more about testing in nonclinical settings and screening in clinical settings.
White Blood Cell Count
White blood cells are a subset of cells produced in bone marrow whose primary role is to fight infection. A white blood cell count is one of the panel of tests included in the CBC that measures not only the total number of leukocytes but also the different types of white blood cells in a blood sample, namely:
Within the context of HIV, an elevated WBC typically means that your body is fighting an infection. Other tests can then be performed to pinpoint the cause.
An elevation of certain white blood cells may indicate a specific type of infection or an allergic inflammatory response. For example, higher than normal eosinophils may suggest a parasitic infection like toxoplasmosis, while elevated basophils can develop in people with a hypersensitive drug reaction.
A decrease in white blood cells may be the result of HIV medications , a minor viral infection, or a major opportunistic infection like tuberculosis.
CD4 T-cell lymphocytes are a type of white blood cell that HIV preferentially targets and infects. For this reason, they serve as the primary marker of your immune status if you have HIV.
There Are Several Types Of Hiv Test This Website Can Help You Learn More About Different Types Of Hiv Test Here Are The Basic Types Of Test:
HIV Antibody Tests Antibody tests do not detect the HIV-virus itself, but detect a protein called an antibody, which is produced by your body in response to the virus. Antibodies are produced by the immune system after it has had time to react to the new infection, which means antibodies are not detectable in the blood or saliva immediately. The window period for antibody-only tests is about 1 month on average, but can take up to 3 months in some people.
Rapid HIV Tests There are several types of rapid test for HIV, all of which are antibody-only tests. Rapid tests are point-of-care tests . These tests use either saliva or a small amount of blood and provide a result within 30 minutes. Madison Clinic uses a rapid test that takes a few drops of blood and provides a result in less than 60 seconds. The advantage of using a rapid test is that you dont have to wait to get the results however, because a rapid test has a longer window period than other tests and because it is a point-of-care test which is more subject to error in its use than a laboratory test, it is recommended that people getting a rapid HIV test also get a standard laboratory test to confirm the results.
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Basic Facts About Aids
- AIDS stands for acquired immune deficiency syndrome. Its also called advanced HIV infection or late-stage HIV.
- AIDS is a set of symptoms and illnesses that develop when an advanced HIV infection has destroyed the immune system.
- Fewer people develop AIDS now, as more people are on treatment for HIV and staying well.
Although there is no cure for HIV, with the right treatment and support, people living with HIV can enjoy long and healthy lives. To do this, its especially important to commit to taking treatment correctly.
What Do Blood Tests Show
Blood tests show whether the levels of different substances in your blood fall within a normal range.
For many blood substances, the normal range is the range of levels seen in 95 percent of healthy people in a certain group. For many tests, normal ranges vary depending on your age, gender, race, and other factors.
Your blood test results may fall outside the normal range for many reasons. Abnormal results might be a sign of a disorder or disease. Other factorssuch as diet, menstrual cycle, physical activity level, alcohol intake, and medicines also can cause abnormal results.
Your doctor should discuss any unusual or abnormal blood test results with you. These results may or may not suggest a health problem.
Many diseases and medical problems cant be diagnosed with blood tests alone. However, blood tests can help you and your doctor learn more about your health. Blood tests also can help find potential problems early, when treatments or lifestyle changes may work best.
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Lab Tests And Why They Are Important
As part of your HIV care, your provider will order several laboratory tests. The results of these lab tests, along with your physical exam and other information you provide, will help you and your provider work together to develop the best plan to manage your HIV care so that you can get the virus under control, protect your health, and reduce the chance that you will pass the virus to others.
Your healthcare provider will repeat some of these tests as part of your ongoing HIV care to continue to assess your health and how well your HIV treatment is working.
The lab tests may include:
- CD4 Percentage: This measures how many of your white blood cells are actually CD4 cells. This measurement is more stable than CD4 counts over a long period of time, but, for most people, the CD4 count remains a more reliable measure of how well your immune system is working than the CD4 percentage.Why its important: This measurement is less likely to vary in between blood tests than CD4 counts .
- Complete Blood Count : This is a measure of the concentration of red blood cells, white blood cells, and platelets in a sample of your blood.Why its important: A CBC is one of the most commonly ordered blood tests. It can reveal infections, anemia , and other medical issues.
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Diagnosis Of Hiv Infection
Tests used for the diagnosis of HIV infection in a particular person require a high degree of both sensitivity and specificity. In the United States, this is achieved using an algorithm combining two tests for HIV antibodies. If antibodies are detected by an initial test based on the ELISA method, then a second test using the Western blot procedure determines the size of the antigens in the test kit binding to the antibodies. The combination of these two methods is highly accurate
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What We Know About The Types Of Hiv Tests
HIV tests are very accurate, but no HIV test can detect HIV immediately after a person gets the virus. Some kinds of tests detect HIV sooner than others. In general, nucleic acid tests can detect HIV the soonest, followed by antigen/antibody tests, and then antibody tests.
Most rapid tests and self-tests are antibody tests. Your immune system makes antibodies when youre exposed to bacteria or viruses like HIV. Antibody tests look for these antibodies in your blood or oral fluid. In general, antibody tests that use blood from a vein can detect HIV slightly sooner after infection than tests done with blood from a finger prick or with oral fluid.
More Information With a rapid antibody screening test, results are ready in 30 minutes or less.
More Information
A self-test is an antibody test you can buy at a pharmacy or online. There is currently one available FDA-approved self-test, the OraQuick In-Home HIV Test.
The OraQuick In-Home HIV Test gives fast results at home. You have to swab your mouth to get an oral fluid sample and use a kit to test it. Results are ready in 20 minutes. If the test says you have HIV, you should go to a health care provider to get follow-up testing. The manufacturer provides confidential counseling and refers you to follow-up testing sites.
Where Can I Get Tested For Hiv
Your health care provider can give you an HIV test. HIV testing is also available at many hospitals, medical clinics, substance use programs, and community health centers. Use this CDC testing locator to find an HIV testing location near you.
You can also buy a home testing kit at a pharmacy or online.
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Where Can People Find Free Hiv Testing Locations
The CDC maintains a list of HIV testing locations for people who want to find out whether they have contracted the virus. This National HIV and STD Testing Resource can be accessed at . This site includes the ability to search for free testing locations as well as locations that provide rapid tests. Some clinics only provide HIV testing. However, sexually transmitted diseases clinics routinely provide HIV testing along with testing for diseases like chlamydia, gonorrhea, syphilis, and herpes.
Viral Load And Cd4 Levels
When someone contracts HIV, the virus begins to take over specific cells in the immune system, called CD4 cells.
When the CD4 cells replicate, the HIV cells inside them also replicate. HIV hijacks the cellular machinery of CD4 cells to reproduce and shed more HIV, which means the viral load increases.
As the HIV viral load increases, the number of healthy CD4 cells decreases as they are destroyed creating HIV copies.
Treatment aims to produce a low viral load and a high CD4 count. When a person has achieved this, their HIV is well controlled.
A low or undetectable viral load means the virus is not progressing. It also means that HIV is not attacking the immune system as actively. This gives the immune system the chance to rebuild its healthy cell count. As a result, the number of CD4 cells in the persons body will increase as their viral falls.
A doctor will usually test a persons viral levels when they first diagnose HIV. Doctors will recommend an HIV test if someone presents symptoms of HIV or if they may have come into contact with the virus.
People living with HIV will have repeat viral load tests throughout their lives to monitor the condition. They should get tested once every 3 to 4 months during treatment.
Additionally, a person should get tested due to any alteration in their medication or if their symptoms change.
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What Is It Used For
An HIV test is used to find out if you have been infected with HIV. HIV is the virus that causes AIDS . Most people with HIV dont have AIDS. People with AIDS have an extremely low number of immune cells and are at risk for life-threatening illnesses, including dangerous infections, a severe type of pneumonia, and certain cancers, including Kaposi sarcoma.
If HIV is found early, you can get medicines to protect your immune system. HIV medicines may prevent you from getting AIDS.
What Happens During An Hiv Test
You will either get a blood test in a lab, or do your own test at home.
For a blood test in a lab:
- A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
For at home test, you will need to get a sample of saliva from your mouth or a drop of blood from your fingertip.
- The test kit will provide instructions on how to get your sample, package it, and send it to a lab.
- For a saliva test, you will use special spatula-like tool to take a swab from your mouth.
- For a fingertip antibody blood test, you will use a special tool to prick your finger and collect a sample of blood.
For more information on at-home testing, talk to your health care provider.
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What Are The Different Types Of Hiv Testing
There are three main types of HIV tests: antibody tests, RNA tests, and a combination test that detects both antibodies and viral protein called p24 . All tests are designed to detect HIV-1, which is the type of HIV in the United States. Some antibody tests and the combination test can also detect HIV-2 infections, which are usually limited to West Africa. No test is perfect tests may be falsely positive or falsely negative or impossible to interpret .
Positive test results are reportable to the health department in all 50 states and include the patients name. This information is then reported to the CDC so that the epidemiology and infection spread rates can be monitored. The names sent to the state remain confidential and will not be reported to employers, family members, or other such people. Some states allow anonymous testing in which the patients name is not recorded.
HIV antibody tests: HIV possesses many unique proteins on its surface and inside the virus itself. When someone is infected with HIV, their body produces proteins designed to tag the virus for elimination by the immune system. These proteins are called antibodies, and they are directed against the unique proteins of HIV. Unfortunately, these HIV antibodies do not eliminate the virus, but their presence serves as a marker to show that someone is infected with HIV. HIV antibody tests are the most commonly used tests to determine if someone has HIV.
Why Is Hiv Testing Important
Knowing your HIV status can help keep youand otherssafe.
If you are HIV negative:
Testing shows that you dont have HIV. Continue taking steps to avoid getting HIV, such as using condoms during sex and, if you are at high risk of getting HIV, taking medicines to prevent HIV . For more information, read the ClinicalInfo fact sheet on HIV prevention.
If you are HIV positive:
Testing shows that you have HIV, but you can still take steps to protect your health. Begin by talking to your health care provider about antiretroviral therapy . People on ART take a combination of HIV medicines every day to treat HIV infection. ART is recommended for everyone who has HIV, and people with HIV should start ART as soon as possible. ART cant cure HIV, but HIV medicines help people with HIV live longer, healthier lives.
A main goal of ART is to reduce a persons viral load to an undetectable level. An undetectable viral load means that the level of HIV in the blood is too low to be detected by a viral load test. People with HIV who maintain an undetectable viral load have effectively no risk of transmitting HIV to their HIV-negative partner through sex.
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Window Periods And Accuracy
The window period is the time immediately after infection, during which tests cannot always detect antibodies or p24 antigen, and so may give a false negative result. It is hard to say exactly how long the window period for any test lasts, as there are variations between individuals and it is a difficult topic to research . Nonetheless, it is estimated that the median window period for fourth-generation tests is 18 days, with half of all infections being detected between 13 and 24 days after exposure. While occasionally this period will be a little longer, 99% of HIV-infected individuals would be detectable within 44 days of exposure.
Therefore, UK guidelines state that an antibody/antigen laboratory test will detect the great majority of individuals who have been infected with HIV four weeks after specific exposure.
antigen
Something the immune system can recognise as ‘foreign’ and attack.
Fourth-generation laboratory tests are extremely accurate. The key measures of accuracy are sensitivity and specificity . In terms of sensitivity, a Centers for Disease Control and Prevention review identified four studies of two different assays, with sensitivity always above 99.7% for established infection. A Health Protection Agency evaluation found that nine out of the ten tests they evaluated had a sensitivity of 100%, while a French evaluation found that ten of twelve tests had a sensitivity of 100%. The lowest sensitivity was 99.8%.
Basic information on testing
Changing Attitudes About Hiv
When someone is diagnosed with HIV, other people may have negative attitudes and beliefs about that person’s behaviour, lifestyle or circumstances in life. These negative associations form what’s called stigma, an experience that can decrease quality of life because it includes:
- judging
Efforts to end stigma will help to:
- prevent new infections
- ensure that people living with HIV receive the care, treatment and support they need
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What We Know About Hiv Testing
About 1 in 7 people in the United States who have HIV dont know they have it. Getting an HIV test is the only way to know your HIV status. HIV testing is easier, more available, and more accurate than ever. There are three types of HIV tests available in the United States some can detect HIV sooner than others.