Human Immunodeficiency Virus (HIV)
HIV is the virus that causes AIDS (acquired immunodeficiency syndrome), a life-threatening disease. Initially, an HIV infection may cause no symptoms or cause non-specific, flu-like symptoms that resolve after a short time period. The only way to determine whether a person has been infected is through HIV testing.
If the infection is not detected and treated, eventually symptoms of AIDS emerge and begin to progressively worsen. Without treatment, HIV destroys the immune system over time and leaves a person's body vulnerable to debilitating infections.
HIV is spread in the following ways:
- By having sex with an infected partner
- By sharing needles or syringes (such as with intravenous injection drug abuse)
- During pregnancy or birth; if a pregnant woman is infected with HIV, the virus can be passed to and infect her developing baby.
- Through contact with infected blood
- In the U.S. today, because of screening blood for transfusion and heat-treating techniques and other treatments of blood derivatives, the risk of getting HIV from transfusions is extremely small. However, before donated blood was screened beginning in 1985 in the U.S. and before treatments were introduced to destroy HIV in some blood products, such as factor 8 and albumin, HIV was transmitted through transfusion of contaminated blood or blood components.
Why Get Screening?
Screening for HIV is now part of routine healthcare in the United States and is an important part of wellness and prevention. This is because diagnosis early in the course of infection leads to timely, effective treatment that decreases the risk of progression to AIDS. A major National Institutes of Health (NIH) clinical trial published in 2015 found that individuals with HIV have a lower risk of developing AIDS and other serious illnesses if they start antiretroviral therapy sooner rather than later.
Early diagnosis also has important benefits for others and society at large. Thousands of people are diagnosed with HIV each year, and about 1 in 8 people in the United States with HIV are unaware that they have it. An individual can prevent further disease spread by learning their status, modifying behavior and not exposing others to infected blood or body fluids. Pregnant women who have HIV can start treatment to prevent spreading the disease to their children.
If an HIV screening test shows a person is not infected, he or she can take steps to avoid infection. For individuals who are HIV-negative but at high risk for HIV, the Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) recommend that they consider taking pre-exposure prophylaxis (PrEP), a daily pill to help prevent infection. For people taking PrEP consistently, the risk of HIV infection is significantly lower compared to those who did not take it.
Know Your Risk
Several situations put you at high risk of contracting HIV:
- You've had unprotected sex with more than one partner.
- You have or have had a sexually transmitted disease (STD), which appears to make people more susceptible to and at higher risk for acquiring HIV infection during sex with infected partners.
- You're a man who has had sexual contact with another man.
- You have exchanged sex for money or drugs or had anonymous sex.
- You use or used injection drugs and are likely to have shared unsterilized needles.
- You have an HIV-positive sexual partner.
- You have had sex with anyone who falls into one of the categories listed above or are uncertain about your sexual partner's risk behaviors.
- You've been diagnosed with or treated for hepatitis or tuberculosis (TB).
How often you are tested should depend on your risk, activities, and sexual contacts. For example, during a long-term, truly monogamous sexual relationship, you may want just one test. However, if you or your partner have had sexual contact with more than one person in recent months, your risk of infection is greater. If you or a person with whom you've had sexual contact (even unwanted sexual contact) engaged in some risky behavior, you have even more reason to be tested.
Different types of tests are available for HIV screening:
- Combination HIV antibody and HIV antigen test—this is the recommended screening test for HIV. It is available only as a blood test. It detects the HIV antigen called p24 plus antibodies to HIV-1 and HIV-2. (HIV-1 is the most common type found in the United States, while HIV-2 has a higher prevalence in parts of Africa.) By detecting both antibody and antigen, the combination test increases the likelihood that an infection is detected soon after exposure. These tests can detect HIV infections in most people by 2-6 weeks after exposure.
- 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. HIV antibody tests can detect infections in most people 3-12 weeks after exposure.
Various options are available for getting tested:
- A blood or oral sample can be collected in a healthcare provider's office or a local clinic and sent to a laboratory for testing. In these same settings, a rapid test may available in which results are generated in about 20 minutes.
- A home collection kit approved by the U.S. Food and Drug Administration (FDA) is available for HIV antibody testing. This allows a person to take a sample at home and then mail it to a testing center. Results are available over the phone, along with appropriate counseling.
- The FDA has approved an HIV test for home use. The testing kit is the same as that used in many healthcare providers' offices and clinics in which an oral sample is collected for testing and results are available in about 20 minutes. Though the home test is convenient, it has limitations. It is less sensitive than a blood test so the home test may miss some cases of HIV that a blood test would detect and it is not as accurate when it is performed at home by a lay person compared to when it is performed by a trained healthcare professional. Care must be taken to avoid errors when performing the test. (For more, see the article on Home Testing, Avoiding Errors.)
Screening tests have limitations, so it is important to remember that:
- A negative screening test means only that there is no evidence of disease at the time of the test. If you have increased risk of HIV infection but negative screening results, it is very important to get screening tests on a regular basis.
- HIV tests will not detect the virus immediately after infection. Still, talk to your healthcare provider immediately if you think you’ve been infected. If exposure to the virus is recent, then antibody levels may be too low to detect. If an initial test is negative, it may be necessary to repeat testing at a later time with another antibody test or combination HIV antibody/antigen test. In the case of a negative result, the CDC recommends retesting three months after likely exposure.
- A positive screening test is not a diagnosis. A positive result must be followed by a second antibody test that differentiates between HIV-1 and HIV-2 to establish a diagnosis.
For more details on HIV screening, see the article on HIV Antibody and p24 Antigen.
- The Centers for Disease Control and Prevention (CDC) recommends that everyone 13 to 64 years old have an HIV screening test at least once. The CDC recommends getting tested each year if you've engaged in an activity that can put you at increased risk of infection and spreading the disease. Additionally, men who have sexual contact with other men should be tested be tested every three to six months.
- The United States Preventive Services Task Force (USPSTF) recommends that all teens and adults ages 15 to 65 be screened for HIV infection. It also recommends that younger adolescents and older adults at increased risk undergo screening for HIV. As for how often, the Task Force says a reasonable approach is one-time testing for all people ages 15 to 65 and at least annual screenings for those at very high risk of HIV, such as men who have sex with men, injection drug users, and those who live or receive medical care in areas where the rate of HIV infection is high. Individuals at increased but not very high risk may be screened less frequently than every year. The USPSTF recommends every three to five years as a guideline. The Task Force points out that risk is "on a continuum" and health professionals should use their own discretion in deciding how frequently to test people for HIV.
- The American College of Physicians agrees with the CDC that everyone aged 13 to 64 be offered an HIV screening test in healthcare settings. It also recommends that healthcare practitioners should determine the frequency of repeat screening on an individual basis.
- The American Academy of Pediatrics (AAP) recommends targeted HIV screening for all sexually active youth. In addition, the academy advises routine testing starting at age 16 for all teens who live in areas where prevalence is high; that is, where more than 1 in 1,000 individuals are infected.
- For recommendations specific for pregnant women, see the article on Pregnancy.
Aside from these recommendations, certain individuals should get tested and learn their status. These include:
- People diagnosed with hepatitis, TB, or an 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
Talk to your healthcare provider
Don't be surprised if a healthcare practitioner, in any care setting, offers you an HIV screening test, in keeping with CDC recommendations. If your healthcare provider does not bring up sexual health topics, you can simply ask for a test or a risk assessment. You can also use confidential services to obtain testing or counseling.
Resources & Links
For confidential information, you can call the STDs and HIV/AIDS hotline of the CDC: 800-CDC-INFO (232-4636).
To find a testing site near you, visit National HIV and STD Testing Resources
KidsHealth.org: HIV and AIDS
MedlinePlus: Screening and diagnosis for HIV
Mayo Clinic: HIV/AIDS - Preparing for your appointment
AIDSinfo: HIV Testing
Sources Used in Current Review
Qaseem, A. et al. (2009 January 20). Screening for HIV in health care settings: A guidance statement from the American College of Physicians and HIV Medicine Association. Annals of Internal Medicine. Available online at http://annals.org/aim/article/744218/screening-hiv-health-care-settings-guidance-statement-from-american-college. Accessed 11/6/2016.
(2011 October 31). The pediatrician's role in preventing HIV infection. American Academy of Pediatrics. Available online at https://healthychildren.org/English/news/Pages/The-Pediatricians-Role-in-Preventing-HIV-Infection.aspx. Accessed 11/6/2016.
(2013 April). Human Immunodeficiency Virus (HIV) infection: Screening. U.S. Preventive Services Task Force. Available online at https://www.uspreventiveservicestaskforce.org/Page/Document/UpdateSummaryFinal/human-immunodeficiency-virus-hiv-infection-screening. Accessed 11/6/2016.
(2015 May 27). Press release: Starting antiretroviral treatment early improves outcomes for HIV-infected individuals. National Institutes of Health. Available online at https://www.nih.gov/news-events/news-releases/starting-antiretroviral-treatment-early-improves-outcomes-hiv-infected-individuals. Accessed 11/6/2016.
(Updated 2016 January 22). Working in healthcare and HIV. AVERT. Available online at http://www.avert.org/hiv-transmission-prevention/working-healthcare. Accessed 11/6/2016.
(2016 May 23). Recommendations for HIV prevention with adults and adolescents with HIV. Centers for Disease Control and Prevention. Available online at http://www.cdc.gov/hiv/guidelines/personswithhiv.html. Accessed 11/6/2016.
(2016 October 27). HIV and AIDS: Testing. Centers for Disease Control and Prevention. Available online at https://www.cdc.gov/hiv/basics/testing.html. Accessed 11/6/2016.
(2016 June 20). HIV testing. Centers for Disease Control and Prevention. Available online at https://www.cdc.gov/hiv/testing. Accessed 11/6/2016.