The CDC believes that many people in the United States have HIV but have not been tested for it. These people do not know they are infected and that they need medical care. Without being identified as a carrier of HIV they can unknowingly pass HIV infection on to others.
Some people do not find out that they are infected with HIV until they get sick or show symptoms and go to a clinic or hospital and get a test to find out their HIV status. Since most people don’t have symptoms for years, they do not find out their status until later in the disease progression. By the time they find out they are infected, they have missed opportunities to take care of their health and avoid passing the infection on to others. It is important for anyone at risk of HIV infection to get tested. Those who are uninfected can learn to take steps to avoid infection and those who are infected can be proactive to take care of their own health as well as to avoid passing the infection on to others.
HIV Antibody Tests
The first HIV antibody test became available in 1985. Since then, new HIV antibody tests have been developed and approved by the Food and Drug Administration (FDA). Currently, these antibody tests involve a two-step process utilizing a screening test and, when the screening test is reactive it is positive, which is a confirmatory test.
Step 1: Screening Test. The first test done on a specimen is a screening test called an enzyme-linked immunosorbent assay (EIA or ELISA). This type of test screens for the presence of antibodies to HIV in blood, urine, or oral fluid. Screening tests are inexpensive and highly accurate.
Most HIV antibody screening tests are conventional, in that the specimen is collected from the client and sent to a laboratory for testing. If a screening test is negative (no HIV antibodies are detected), the results can be released to the client. If the screening test is reactive (positive) at the laboratory, a confirmatory Western Blot test is conducted on the same sample.
Rapid tests are also screening tests, but they are conducted at the test site, often with the client present, and negative results are available in under an hour. Reactive (antibodies detected) results from a rapid test must be confirmed. This is done because there is a small chance that an HIV screening test may detect proteins related to other autoimmune diseases and react to those proteins with a false positive result.
Step 2: Confirmatory Testing. If a rapid test is reactive, an additional specimen must be drawn from the client and sent to the lab for confirmatory Western Blot testing. The HIV Western Blot detects antibodies to the individual proteins that make up HIV. This test is much more specific, and therefore more costly, than the EIA screening test.
False Results. Someone not infected with HIV may test reactive on a screening test because the test detected proteins related to other autoimmune diseases and gave a positive result. For this reason, it is critical that reactive screening tests be verified with a confirmatory test and that clients not be told they are infected with HIV unless the confirmatory test verifies that HIV antibodies are present. A false negative may result during the window period before antibodies have been created. For people at high risk who receive a negative HIV test, retesting at three months is recommended. All babies born to mothers with HIV will have HIV antibodies present in their blood but may not actually have HIV.
Antibody Testing Specimen Options
HIV antibody tests are designed to detect HIV antibodies in blood, urine, or oral fluid (oral mucosa transudate) samples.
The most frequently used HIV antibody test detects HIV antibodies in blood. Depending on test type, blood from a venipuncture or fingerstick will be used. This is the test that is used most often in public health clinics and doctors’ offices. Most rapid screening tests use fingerstick blood.
As with all screening tests, reactive blood screening tests must be confirmed with a Western Blot test. For most HIV testing, this confirmatory testing is done on the same sample in the laboratory. For reactive rapid tests, an additional sample needs to be drawn and sent to the laboratory.
This test detects HIV antibodies in the mucous membrane (oral mucosal transudate) of the mouth. The oral test kit uses a special collection device that looks like a toothbrush. No needles are used. There are some rapid tests that use oral fluids. Many public health clinics also offer oral fluid testing. Some provide rapid oral fluid testing. As with all screening tests, positive oral fluid screening tests must be confirmed with a Western Blot test.
It is important to note that although antibodies to HIV can be found in saliva and oral fluids, these fluids do not contain sufficient amounts of the virus to be infectious and therefore are not considered a risk for transmitting the virus.
A urine-based test for HIV antibodies is available for use only in physician’s offices or medical clinics. It tests for HIV antibodies in the urine. It is important to note that, even though antibodies to HIV can be found in urine, urine is not considered a risk for transmitting the virus. As with all screening tests, a positive urine HIV screening test must be confirmed with a Western Blot test, which can be done on the same specimen.
Rapid HIV Test
The rapid HIV test is a screening test that can provide results in less than an hour. Rapid testing can be conducted on blood and/or oral mucosal transudate, depending on the type of test. As with all screening tests, any reactive rapid test result must be confirmed with a conventional Western Blot test.
Home Test Kits
[Material in this section is from FDA, 2012.]
The first licensed and FDA-approved test kit for home HIV antibody testing is the “Home Access HIV-1 Test System” manufactured by Home Access Health Corporation. The test requires a few drops of blood, which is mailed to the company in a safe mailer. If the screening test is reactive, a confirmatory Western Blot test is done by the same laboratory so that final results are available to clients. The client calls the company to learn the results over the phone.
The second test kit was approved when, “On July 3, 2012 the Food and Drug Administration (FDA) approved the ‘OraQuick In-Home HIV Test,” a rapid home-use HIV test kit that does not require sending a sample to a laboratory for analysis. The kit provides a test result in 20 to 40 minutes, and you can test yourself in your own home. The kit, which tests a sample of fluid from your mouth, is approved for sale in stores and online to anyone age 17 and older.
The FDA noted that positive test results using the OraQuick test must be confirmed by followup laboratory-based testing, and that the test can be falsely negative for reasons that include having been exposed to HIV within three months before testing. Those who engage in risky behaviors should be re-tested on a regular basis and should not interpret a negative test to mean that such high-risk behaviors are safe.
If you are unsure if an HIV test is FDA approved, you can check the FDA list, which is available online (see Resources section at the end of the course).
Internet Test Kits
Although other home test kits may be ordered over the Internet, they may not be approved by the FDA and are not guaranteed to be accurate. The CDC does not recommend using any test that has not been approved by the FDA.
Other HIV Tests
There are several other methods for testing HIV, including the p24 antigen test, the plasma HIV RNA or proviral DNA test, and the HIV viral load test. Tests and testing procedures are constantly being refined and updated.
p24 Antigen Test
This blood test measures a core protein of HIV. This protein occurs during primary infection (the first weeks of infection) but may disappear as soon as antibodies to the virus are present. Because of this, and because of the expense of the test, p24 antigen tests are currently only available under limited circumstances.
Plasma HIV RNA or Proviral DNA Tests
These blood tests may be run on people with suspected new HIV infection. They are expensive and not used as screening tests for the general public. However, anyone who has had a potential exposure to HIV through unprotected sex or sharing needles, and who presents with symptoms of primary infection (usually seen within the first 2 weeks of infection with HIV) should ask their medical practitioner if this test is advisable.
HIV Viral Load Test
This test measures the amount of HIV in an infected person’s bloodstream. It is rarely used to diagnose HIV infection. It is most often used in individuals who are HIV-positive to measure the effectiveness of antiretroviral medications used to treat HIV infection.
Getting Tested for HIV
Who Should Be Tested?
Anyone who has put themselves at risk through anal, vaginal, or oral sex, or shared needles and anyone who has had an occupational exposure, may benefit from HIV testing. People may have partners with risk factors, and these people (along with their partners) should consider testing. For occupational exposure, refer to your employer protocol.
Where to Test for HIV
People may get an HIV test at public health departments, through their medical provider, family planning, or sexually transmitted disease clinics and at some community clinics.
With confidential HIV testing, clients do give their real name, and the information about their testing is maintained in medical records. Their results are confidential. Results and testing information are not released to others except when medically necessary or under special circumstances such as when they sign a release for the results to be given to another person or agency. HIV is a reportable condition, therefore confidential HIV results are reported to local public health officials.
An anonymous HIV antibody test means that the clients don’t give their name and the person who orders or performs the test does not maintain a record of the name of the person they are testing.
Informed Consent Required
HIV testing can only be done with the person’s consent. Consent may be contained within a comprehensive consent for medical treatment. It can be verbal or written but must be specific to HIV and must be documented. There are some rare exceptions where a person can be tested without their consent, including source testing relating to occupation exposures and legally mandated situations specified in state law.
Testing Information and Risk Assessment Required
Aside from the exceptions listed above, all people tested for HIV should be assessed for their risk of infection and unless previously tested and having declined information, be provided with appropriate information about the test, including, but not limited to:
- The benefits of learning their HIV status and the potential dangers of the disease
- How HIV is transmitted and way in which it can be prevented
- Meaning of HIV test results and the importance of obtaining the results
- As appropriate, the availability of anonymous testing and the differences between anonymous and confidential testing
HIV Antibody Test Results
Antibody test results can be negative, positive, or indeterminate. A negative test result is not certain until you have passed the window period.
The Window Period
It is important to remember that HIV antibody testing has a window period. The window period is the time between initial infection with the virus and when the HIV-infected person develops enough antibodies to be detected by the antibody test. Until the infected person’s immune system makes enough antibodies to be detected, the test will be negative even though the person is infected with HIV.
Some infected people are able to produce antibodies as early as 2 weeks after infection. Almost everyone will develop enough antibodies to be detected by 12 weeks after infection. Unfortunately, there is no way to know how long each infected person will take to develop antibodies. However, virtually everyone who is infected will produce enough antibodies for detection by 12 weeks (3 months). Therefore, to be sure, people should test 3 months after the last potential HIV exposure even if an initial screening is negative.
Because people who are newly infected have so few antibodies to fight HIV, the virus can grow and multiply unchecked. During this time, they can have a large amount of virus in their blood, making them highly infectious for HIV. During the window period it is possible for an infected person to test negative (before they develop antibodies) but still be able to infect another person.
If the test result is negative, it means one of two things:
- Either the person is not infected with the virus, or
- The person became infected recently and has not produced enough antibodies to be detected by the test
If a person is concerned about a recent incident, they should test 3 months from the date of their last possible exposure. A negative test result does not mean a person is immune to HIV. If risky behavior continues, infection may occur.
A positive confirmatory test indicates the presence of HIV antibodies and that the person:
- Is infected with HIV
- Can spread the virus to others through unsafe sexual practices, sharing contaminated injection equipment, or breastfeeding
- Is infected for life
Occasionally, a Western Blot test result will come back with an indeterminate or inconclusive test result. If a person has recently engaged in behaviors that put them at risk for getting HIV, it could mean that they are newly infected with HIV and are slowly developing antibodies, or seroconverting.
If seroconversion is suspected, RNA testing can determine if the HIV virus is present. If RNA testing is not available, a second specimen should be gathered and tested with an antibody test. If seroconversion is present, this second test may give a positive result.
Indeterminate results are not always indicative of seroconversion. They can also be caused by cross reaction with other proteins from several sources, including pregnancy, other autoimmune diseases, and recent influenza vaccinations.
For low-risk people when seroconversion is not suspected, retesting should be conducted at 1 month and at 3 months from the last possible exposure to verify that they are not infected. Non-infection is indicated if the subsequent tests continue to be indeterminate (without additional HIV antibody protein bands) or negative.
Indeterminate results for low-risk clients are rare. It is possible that some uninfected people may always test indeterminate due to the cross reaction from protein bands from something other than HIV. Other uninfected people who first test indeterminate may clear their bodies of those other proteins that are causing the cross reaction and, in subsequent tests, test negative. Still others go back and forth between indeterminate and negative.
Counseling messages should explain that only HIV-positive tests indicate infection with HIV and that some people test indeterminate because of non-HIV proteins in their bodies that register on the test. No further testing for other diseases is indicated.
Advantages of Early Testing for HIV Infection
New drug therapies for HIV infection can sustain an infected person’s health for long periods of time. Early detection allows people with HIV the option to receive medical treatment sooner, take better care of their immune system, and stay healthier longer. Additionally, early detection of HIV allows people to take precautions not to infect others.
- Is immune to HIV and can never become infected.
- Is infected with HIV and will remain infected for life.
- Has never been exposed to HIV.
- May have been exposed to HIV but not yet produced enough antibodies to be detected by the test.
- Is infected with HIV and can spread the virus to others.
- Cannot spread the virus until symptoms of AIDS develop.
- Can be cured with current antiviral drugs.
- Does not have AIDS.
Counseling with HIV Testing
The person who provides HIV test counseling to clients should direct the counseling toward increasing client’s understanding of their own risk of acquiring or transmitting HIV, motivating them to reduce their risk, and assisting them to build skills to reduce their risk.
Pre-test counseling should be based on recommendations of the CDC’s 2006 Revised Recommendations for HIV Testing of Adults, Adolescents, and Pregnant Women in Health-Care Settings (latest available).
Pre-test counseling should always:
- Assist the individual to set realistic behavior-change goals and establish strategies for reducing their risk of acquiring or transmitting HIV
- Provide appropriate risk reduction skills-building opportunities to support their behavior change goals
- Provide or refer for other appropriate prevention, support, or medical services
Those who test HIV negative should be offered an individual counseling session at the time they receive their test results. For those clients who test HIV-positive, counseling can’t just be offered, it must be provided or referred and in addition to what is provided to HIV-negative clients, must also include:
- If confidentially tested, the information that HIV is a reportable condition
- Either the provision of partner notification support or referral to public health for these services
- Appropriate referrals for alcohol and drug and mental health counseling, medical evaluation, TB screening, and HIV prevention and other support services
Information about a person’s HIV test and results is confidential and must not be shared with others. People who perform HIV counseling and testing in public health departments or health districts must sign strict confidentiality agreements. These agreements regulate the personal information that may be revealed in counseling and testing sessions as well as test results. HIV test results are kept in locked files, with only a few appropriate staff members having access to them.
HIV Testing: Pregnancy
[Material from this section was retrieved on January 8, 2018 from https://www.cdc.gov/hiv/group/gender/pregnantwomen/opt-out.html.]
In the 2006 Revised Recommendations for HIV Testing of Adults, Adolescents, and Pregnant Women in Health-Care Settings, CDC recommended the opt-out approach to testing for all adult and adolescent patients in healthcare settings, including pregnant women.
These recommendations emphasize:
- Universal “opt-out” HIV testing for all pregnant women early in every pregnancy.
- A second test in the third trimester in certain geographic areas or for women who are known to be at high risk of becoming infected (eg, injection-drug users and their sex partners, women who exchange sex for money or drugs, women who are sex partners of HIV-infected persons, and women who have had a new or more than one sex partner during this pregnancy).
- Rapid HIV testing at labor and delivery for women without a prenatal test result.
- Exploration of reasons that women decline testing.
Studies show that the opt-out approach can:
- Increase testing rates among pregnant women, thereby increasing the number of pregnant women who know their HIV status.
- Increase the number of HIV-infected women who are offered treatment.
- Reduce HIV transmission to their babies.
How is opt-out implemented in the healthcare setting?
Opt-out comprises three steps for healthcare providers to follow to put this approach into practice (CDC recommends all three steps):
- Tell all pregnant women that an HIV test will be performed as part of the standard group of tests for pregnant women.
- Tell all pregnant women that they may decline this test.
- Give all pregnant women information about how to prevent HIV transmission during pregnancy and provide information about treatment for pregnant women who are HIV-positive.
HIV Testing: Sexual Assault
Sexual assault is prevalent in the United States. In 2010 the CDC began annual collection of comprehensive data on sexual violence victimization, including rape, with the National Intimate Sexual Violence Survey (NISVS). The last reported year of data in 2011 indicate that more than 23 million women were raped at some point in their lifetime, and 40% of those rapes took place before the women reached age 18. In addition, nearly 2 million men report being raped at some point in their lifetime (NISVS, 2011). Unfortunately, a study found that rape is hugely underreported in the United States due to women not wanting to report the crime and official records undercounting to “create the illusion of success in fighting violent crime” (Yung, 2014).
For the 12-month period preceding the 2011 data collection, 1,929,000 women reported being raped, and 6,687,000 subjected to other forms of sexual violence. Although rape data for men was not available, 5,797,000 of them reported being subjected to other kinds of sexual violence during that one-year period (NISVS, 2011).
Apart from the emotional and physical trauma that accompany sexual assault, many victims are concerned about HIV infection from the rapist.
Sexual Assault HIV Risks
According to CDC, the odds of HIV infection from a sexual assault in the United States are 2 in 1,000. While this is a low risk, the fear of HIV poses an additional emotional burden on people who have been victims of sexual assault.
When assault victims are worried about HIV, testing can help their healing process. Almost all such HIV tests will be negative and thus provide emotional relief to the victim. The very few who do test HIV-positive will need that information both for obtaining healthcare and as evidence in possible criminal court cases.
Assault and the Window Period
The window period for HIV antibody testing must be taken into account when testing after an assault. Recall that it takes from 2 to 12 weeks after exposure for antibodies to show up in an HIV test. Any test conducted shortly after the assault reveals only the original status of the victim. An early test can, however, provide proof that the victim was HIV-negative at the time of the assault, which may be useful as evidence in a criminal case.
To verify that the victim was not infected by the assault, it is necessary to test again after the window period. If, following an earlier HIV-negative result, the second test is HIV-positive, it indicates that the victim was infected by the assault (assuming no other opportunity for infection occurred in the interim).
When counseling assault victims about the risk of HIV, remember that the risk of HIV is low but there other potentially higher risks to be addressed. The risk of other STDs and pregnancy are much higher than HIV. Victims of sexual assault should be tested for STDs and females given emergency contraception. The emergency contraception hotline number (888 668 2528) should be provided by telephone rape counselors or other health care professionals.
Most experts recommend that a sexual assault victim should go directly to the nearest hospital emergency room, without first changing their clothing, bathing, or showering. Trained staff in the emergency department will counsel the victim, and may also offer testing or referral for HIV, STDs, and pregnancy. It is common practice for the ED physician or Sexual Assault Nurse Examiner (SANE) nurse to take DNA samples of blood or semen from the vagina, rectum, and perineal and adjacent areas, which can be used as evidence against the attacker. Unfortunately many hospitals do not have a dedicated SANE nurse or adequate testing materials and if rape victims are referred to another hospital, the victim may decide to do without the invasive medical care and testing. Some EDs may refer sexual assault survivors to the local health jurisdiction for HIV testing.
Many people feel that the ED setting is a profoundly unpleasant one in which to question sexual assault victims regarding their sexual risks history. However, testing shortly after a sexual assault provides baseline information on their status for various STD infections. All testing to be used for baseline information and legal action should be done confidentially.
The victim needs to consider whether to start post exposure prophylaxis (PEP) independent of the source’s test result, because the time between the attack and the conviction will likely be longer than the 24 to 48 hours time frame recommended for starting PEP.
Partner notification is a voluntary service provided to HIV positive people and their sexual partners or injecting-drug-sharing partners. This service is provided using a variety of strategies to maintain the confidentiality of both the HIV-infected client and the partners.
HIV-infected people are counseled about the importance of their partners’ being notified of exposure to HIV and offered an HIV test. Clients can choose to notify their partners themselves or to have public health staff notify them. When public health staff notify partners, they notify them of their exposure, provide counseling and information, and offer HIV testing without revealing the partner who tested HIV positive.
Partner notification is a critical tool for those notified because it alerts them to the need for being tested. If they are uninfected, they can take steps to ensure they don’t become infected. If infected, they can take steps to care for their own health and to ensure that they do not pass the virus on to others.
AIDS cases have been reportable to the CDC since 1984, when the existence of the syndrome that follows HIV infection was clearly established.