The first HIV antibody test was available in 1985. Since then, new antibody tests have been developed and approved by the Food and Drug Administration (FDA). These tests do not detect the presence of the HIV virus itself but detect the body’s reaction to the virus: the presence of antibodies to HIV. Currently, these antibody tests consist of two steps, a screening test and—when the screening test is reactive (positive)—a confirmatory test.
A positive test result means a person is HIV-positive and can infect others who come in contact with his or her blood, semen, or vaginal fluids. A negative result means there are no antibodies to HIV in the blood at the time of the test. A negative test does not mean a person is HIV-negative—he or she may be infected but not yet have detectable antibodies in the blood.
The U.S Preventative Services Task Force (USPSTF) recommends that clinicians screen for HIV infection in all adolescents and adults ages 15 to 65 years regardless of risk. Gay and bisexual men—and others at high risk—should get tested at least once a year. Younger adolescents and older adults who are at increased risk should also be screened. The Task Force also recommends that clinicians screen all pregnant women for HIV, including those who present in labor who are untested and whose HIV status is unknown (USPSTF, 2013).
HIV screening is recommended for all persons who seek evaluation and treatment for STIs. Testing must be voluntary and free from coercion—patients must not be tested without their knowledge. With notification of the patient that an HIV test will be performed, HIV screening is recommended in all healthcare settings. Specific signed consent for HIV testing should not be required. In most settings, general informed consent for medical care is considered sufficient to encompass informed consent for HIV testing (MMWR, 2010).
Use of rapid HIV tests should be considered, especially in clinics where a high proportion of patients do not return for HIV test results. Positive screening tests for HIV antibody must be confirmed by a supplemental test before the diagnosis of HIV infection can be established (MMWR, 2010).
In most cases the first test done is a sensitive screening test called an enzyme linked immunosorbent assay (ELISA, or EIA). This type of test, using blood, oral fluid, or urine, screens for the presence of antibodies to HIV, which the body starts producing between 2 and 12 weeks after becoming infected. The ELISA test can produce a result in as little as 3.5 hours but most HIV antibody screening tests are sent to a laboratory and tested in batches—a process that can take 1 to 2 weeks. The CDC recommends that laboratories retest all reactive (positive) ELISA tests.
If the screening test is reactive at the laboratory, a confirmatory test called the Western Blot is conducted on the same sample. The Western Blot is only used if the ELISA or rapid test is positive. A few labs use a faster confirmatory test called the indirect immunofluorescence assay (IFA), which also tests for the presence of antibodies in the blood.
Because many people who are tested for HIV either wait until late in the course of their infection to be tested or fail to return to get the results of their test, the CDC recommends offering HIV testing as part of a routine office visit. Rapid tests were developed to accomplish this goal. Rapid HIV testing is recommended for use in settings in which the availability of rapid test results can influence medical care immediately, or as a routine screening tool in settings where HIV prevalence is high or the client is unlikely to return for the results of HIV tests (Bidwell, 2011).
Rapid tests are most commonly performed on a sample from the oral mucosa and have an accuracy rate exceeding 99%. They can be conducted onsite (often with the client present) and negative results can be made available in under an hour. A positive rapid test is considered to be preliminary until a confirmatory test verifies the result.
Kentucky law allows a patient to be informed of a rapid-test positive result while awaiting confirmatory tests. Counseling must be provided regarding the meaning of the test, the importance of confirmatory testing, and the importance of precautions to protect others. A patient may also be informed of a rapid-test positive result “in special cases where immediate actions may be necessary to protect a patient, such as potential perinatal transmission or incidents warranting post exposure prophylaxis.”
HIV screening is done after notifying the patient that the test will be performed. Patients may elect to decline or defer the test, or opt out; if they don’t, their consent is assumed.
The goals of opt-out testing are to:
Opt-out testing does not mean patients must take an HIV test; in general, a patient has the right to refuse an HIV test. (Exceptions include blood and organ donors, military applicants and active duty personnel, federal and state prison inmates under certain circumstances, newborns in some states, and immigrants.)
Under Kentucky law (2011):
For pregnant women, CDC recommends:
Loss of care prior to the start of antiretroviral therapy are of great concern for those individuals in clinical need of antiretroviral therapy. Reasons reported for loss of care vary and include long waiting times at clinics, concerns about the side effects of drug treatment, lack of CD4 testing, and delays in receiving CD4 results. The development of rapid testing devices that can simultaneously screen and confirm the presence of HIV is expected to reduce these gaps in the plan of care for a person who is newly HIV-positive (Wynberg et al., 2014).
One such device screens for anti-HIV antibodies and can then confirm the presence of the virus by detecting an HIV-specific RNA target. This combination of a diagnostic screening with a confirmatory test allows immediate initiation of therapy and counseling and removes the need for the patient to return to the testing facility for either subsequent testing or a final test result. In addition, for populations at high risk for HIV infection, it decreases the window between infection and seroconversion, which is a relatively short period when viral loads are highest and transmission (infection of others) is most likely (Chen et al., 2013).
Partner Counseling and Referral Services (PCRS) have long been an important method for providing comprehensive HIV prevention and treatment services. The CDC recently issued guidelines for Partner Services programs which update the 1998 HIV Partner Counseling and Referral Services Guidance (Song et al., 2012).
Traditionally, PCRS is conducted by trained disease intervention specialists from state or local health departments. As part of service, HIV-infected persons are interviewed and asked to provide information about their sexual or needle-sharing partners. Partners are then located, notified of their potential exposure to HIV, counseled, and offered HIV testing. This approach effectively reaches a population with high HIV prevalence and has been shown to be cost-effective in preventing HIV transmission in the United States (Song et al., 2012).
Recently, novel approaches have been used in an attempt to increase numbers of people who accept PCRS. An enhanced approach, using HIV counselors from community-based organizations in addition to disease intervention specialists, has been demonstrated to be effective and, more recently, the Internet has increasingly been used for partner notification. In practice, the success of partner notification depends on whether HIV-infected individuals are willing to provide information about their partners, the content of the information that they provide, and how they choose to inform their partners that they have been exposed to HIV (Song et al., 2012).
Four referral approaches have been used to notify partners of HIV-infected individuals about their potential exposures to HIV:
Most studies on partner notification have been focused on the assessment of provider referral or self-referral approaches. These studies have shown that the HIV-infected person, particularly men who have sex with men (MSM) and injection drug users, prefer the self-referral approach. However, several systematic reviews of referral strategies have indicated that provider referral, rather than self-referral, may be the most effective means of ensuring successful partner notification (Song et al., 2012).
All state-sponsored testing sites in Kentucky offer free or minimal-cost anonymous or confidential HIV testing. A rapid test called the Ora-Quick test is a type of screening test that provides results within 20 minutes. Several agencies working in association with the Kentucky HIV Prevention Program are currently using rapid testing. Other agencies are being encouraged to begin using rapid testing. To find a testing site near you go to www.hivtest.CDC.gov.