HIV/AIDS Tests

Written by The Healthline Editorial Team | Published on October 29, 2014
Medically Reviewed by Kenneth R. Hirsch, MD on October 29, 2014

HIV/AIDS Testing

According to the Centers for Disease Control and Prevention (CDC), approximately 1.2 million Americans are living with HIV. However, more than 15 percent of them have no idea that they are infected. Although the CDC recommends HIV testing as a routine part of medical care, these guidelines are rarely implemented. Many Americans have never been tested for HIV.

If you haven’t been tested for HIV, consider asking your doctor for an HIV test. You can also seek out free, anonymous HIV testing at a clinic near you. A list of local testing sites can be found at hivtest.org. This government service allows you to search for test sites by zip code.

Who Needs HIV/AIDS Testing?

According to the CDC recommendations, everyone should be offered HIV testing at least once in all healthcare settings. In addition, you should be tested:

  • at least annually, if you are at high risk of infection. High-risk groups include people who have multiple sexual partners or who engage in unprotected sex, as well as intravenous drug users.
  • before entering a new sexual relationship
  • if you just found out you are pregnant
  • if you have symptoms of another sexually transmitted infection (STI)

Several different types of tests are available to detect HIV infection. Not all tests require a blood sample or a doctor’s visit. In 2012, the U.S. Food and Drug Administration (FDA) approved the first rapid test for HIV that can be performed at home.

Tests to Diagnose HIV

A number of different tests can be used to diagnose HIV infection. HIV tests can be performed on:

  • blood samples
  • saliva samples
  • cheek swabs

It can take up to six months after infection for a standard HIV antibody test to turn positive. This is because they look for antibodies to the virus. Antibodies take several months to develop. If you know you have recently been exposed to HIV, tell your doctor. Alternatives to the antibody tests can be used to detect a very recent infection.

Early detection and treatment can greatly improve your health. They can also reduce the risk you pose to any partners. If you know you have been exposed to HIV, seek care as soon as possible. In certain cases, post-exposure prophylaxis may be able to reduce your chances of infection.

Tests to Monitor HIV

In addition to detecting HIV, tests can also be used to monitor the progression of HIV infection. The two most common ways to assess HIV infection are CD4 count and viral load.

CD4 Count

CD4 cells are a type of white blood cell. They are targeted and destroyed by the HIV virus. A healthy person has a CD4 count well above 500 cells per cubic millimiter (cells/mm3).  This number tends to drop as HIV progresses. When a person has a CD4 count under 200 cells/mm3, they are considered to have AIDS.

CD4 count can be used to monitor the effectiveness of HIV treatment. CD4 count should remain level or increase if a treatment is working. The CD4 count is also a good indicator of the overall function of an HIV patient’s immune function, and as it drops below particular levels, your risk for certain diseases increases substantially. Therefore, based upon your CD4 count, your doctor may recommend starting antibiotics to prevent some of these particular infections (prophylactic antibiotics).

Viral Load

This test measures the amount of virus in your blood. Lower viral loads mean that HIV is less likely to affect your health. In addition, people with lower viral loads are less likely to transmit HIV.

Viral load can also be used to monitor the effectiveness of HIV treatment. Effective treatment should reduce the viral load to undetectable levels. HIV infection is extremely unlikely to progress to AIDS in people who can maintain an undetectable viral load.

Drug Resistance

This test determines if your strain of HIV is resistant to any anti-HIV medications. It’s used in making decisions about what the best anti-HIV drug regimen will be for you.

Other Tests for HIV

Monitoring Treatment Effects

If you have HIV, tests may be used to monitor you for side effects of infection and treatment. You may need regular tests for:

  • liver function
  • kidney function
  • cardiovascular and metabolic changes
  • tuberculosis
  • hepatitis
  • sexually transmitted diseases (STDs)
  • urinary tract infections

AIDS-Defining Illnesses

CD4 count is not the only way to determine if HIV has progressed to AIDS. AIDS can be also be defined by the presence of certain opportunistic illnesses or infections.  Those illnesses said to be AIDS defining include:

  • candidiasis (yeast infection) of the bronchi, trachea, or lungs
  • invasive cervical cancer
  • fungal diseases, such as coccidioidomycosis, cryptococcosis, or cryptosporidiosis
  • cytomegalovirus disease
  • encephalopathy (HIV-related)
  • chronic herpes simplex ulcers (lasting longer than 1 month)
  • histoplasmosis, a type of lung infection
  • isosporiasis, an intestinal disease
  • Kaposi's sarcoma (KS)
  • lymphoma
  • mycobacterium avium complex, a bacterial infection
  • pneumocystis carinii pneumonia (PCP)
  • progressive multifocal leukoencephalopathy (PML), a brain disease
  • recurrent pneumonia
  • recurrent salmonella septicemia
  • toxoplasmosis, a parasitic infection of the brain
  • tuberculosis
  • wasting syndrome, or extreme weight loss
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