Dr. Saoji Orthopaedic Clinic And Medilab Pathology Laboratory
Sky Orthopaedics,1st Floor, Nikalas Tower, Central Bazar Road,Nagpur
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Know About HIV P24 Antigen (Screening) (SERUM)
Human immunodeficiency virus (HIV) is the cause of AIDS (acquired immunodeficiency syndrome). HIV screening tests detect the HIV antigen (p24) and/or HIV antibodies produced in response to an HIV infection in the blood. Some tests detect HIV antibody in oral fluid.
When a person becomes infected with HIV, through exposure to the blood or body fluids of an infected individual or a contaminated needle, for example, the virus begins to replicate itself, producing a large number of copies. During the first few weeks of infection, the amount of virus (viral load) and the p24 antigen level in the blood can be quite high.
About 2-8 weeks after exposure to the virus, the immune system responds by producing antibodies directed against the virus that can be detected in the blood. As the initial infection resolves and the level of HIV antibody increases, both virus and p24 antigen levels decrease in the blood.
An HIV infection may initially cause no symptoms or cause flu-like symptoms that resolve after a week or two. The only way to determine whether a person has been infected is through HIV testing.
If HIV is not detected early and treated, it may become a simmering infection that may cause few symptoms for a decade or more. If the infection is still not treated, eventually symptoms of AIDS emerge and begin to progressively worsen. Over time and without treatment, HIV destroys the immune system and leaves a person's body vulnerable to debilitating infections. (You can read more about this in the article on HIV Infection and AIDS.)
Detecting and diagnosing HIV early in the course of infection is important because:
It allows for early treatment that slows progression to AIDS.
An individual can learn of their status and modify behavior so as to prevent the spread of disease.
A pregnant woman can undergo treatment that would help prevent passing the disease to her child.
There are two types of HIV, 1 and 2. HIV-1 is the most common type found in the United States, while HIV-2 has a higher prevalence in parts of Africa.
A few different testing options are available for HIV screening:
Combination HIV antibody and HIV antigen test?the recommended screening test for HIV; it is available only as a blood test.
HIV antibody testing?all HIV antibody tests used in the U.S. detect HIV-1 and some tests have been developed that can also detect HIV-2. These tests are available as blood tests or tests of oral fluid.
p24 antigen testing?this is used alone without the antibody test only in rare cases when there is a question about interference with an HIV antibody test.
Regardless of the type of screening test used, a positive result requires follow up with supplemental testing to establish a diagnosis of HIV. (For more details, see "The Test" section.)
HIV Screening Tests; AIDS Test; AIDS Screen; HIV Serology; p24 Antigen; HIV-1 and HIV-2 Antibody and Antigen Evaluation.
HIV; AIDS; Sexually Transmitted Disease
To determine if you are infected with human immunodeficiency virus (HIV). At least once, when you are 13 to 64 years old; when you think you may have been exposed to the virus; before becoming pregnant or when pregnant; once a year if you are at increased risk of being exposed to the virus.
Several organizations recommend routine screening for HIV:
The Centers for Disease Control (CDC), American College of Physicians (ACP), and the U.S. Preventive Services Task Force (USPSTF) recommend that anyone between the ages of 13 and 64 (or 15 to 65 in the case of the USPSTF) and pregnant women be screened for HIV at least once.
The CDC and American College of Obstetricians and Gynecologists (ACOG) recommend that all pregnant women be screened. Repeat testing in the third trimester may be done for women at high risk. A woman who wants to make sure she is not infected with HIV before getting pregnant may opt to get tested (see Pregnancy: HIV.)
The American Academy of Pediatrics (AAP) advises that all sexually active youth be screened, and that youths between 16 and 18 years old who live in high risk areas (areas where more than 1 in 1,000 people have HIV) be offered HIV testing at least once, regardless of sexual history.
For additional details on screening recommendations, see the articles for Teens, Young Adults, Adults, and Adults 50 and Up.
Annual screening is advised for those at high risk for HIV and is recommended when an individual:
Has had unprotected sex with more than one partner since the last HIV test
Is a man who has had sex with another man (CDC suggests that gay or bisexual men may benefit from more frequent screening, such as every 3 to 6 months)
Has used street drugs by injection, especially when sharing needles and/or other equipment
Has exchanged sex for drugs or money
Has an HIV-positive sex partner
Has had sex with anyone who falls into one of the categories listed above or is uncertain about their sexual partner's risk behaviors
Certain individuals should get at least a one-time test, even if they are not between the ages of 13 and 64, and learn their status. These include:
People diagnosed with hepatitis B or hepatitis C, tuberculosis (TB) or a sexually transmitted disease (STD)
People who received a blood transfusion prior to 1985, or had a sexual partner who received a transfusion and later tested positive for HIV
A healthcare worker with direct exposure to blood on the job
Any individual who thinks he or she may have been exposed