HIV and AIDS | Diagnosis & Tests


Learn More About HIV and AIDS Diagnosis & Tests

Coping With an HIV Diagnosis

Plasma Viral Load Testing

What should I do if I think I may be infected?

If you think you may be infected with HIV, contact your doctor immediately. Even though there is no cure for the disease, early diagnosis and treatment with medicines can be started to slow the progression of the disease. Your doctor will be able to give you more advice about how to take care of yourself if tests show that you have HIV.

Since most people who are infected with HIV appear healthy, a blood test for the virus is necessary to see who has the infection. People who have a positive blood test for HIV are called HIV-positive. Ask your doctor how to obtain confidential testing for HIV. Your doctor can help you understand what the test results mean.

Should I be tested for HIV?

The American Academy of Family Physicians (AAFP) encourages all sexually active people between 18 years and 65 years of age to get tested. Children younger than 18 and adults older than 65 should be tested if they are at an increased risk of getting the virus. The AAFP also recommends that pregnant women be tested for HIV. Most HIV antibody tests done by your doctor are accurate if they are done 2 to 3 months or longer after you think you may have been infected. It takes this long for the antibodies to show up in the blood.

How can my doctor tell that I have HIV?

When HIV enters your body, it moves inside white blood cells called "CD4 lymphocytes." HIV takes over the CD4 cells and makes billions of copies of itself each day. The new cells spread through your body.

Your body tries to defend itself against HIV by making the following:

  1. Antibodies (these attach to the virus and keep it from making new virus).
  2. Special cells called macrophages and natural killer T-cells. These cells help you to get rid of some of the new virus. If antibodies against HIV show up in your blood, you know your body is trying to protect you from the HIV infection you have picked up. However, it's usually several months before your body makes enough antibodies to measure.

So at the time you are infected with HIV, you won't have enough HIV antibodies in your blood to measure, so this test can't give you a diagnosis.

However, when you are experiencing symptoms of HIV, you do have a high level of HIV RNA in your blood (RNA is the short name for "ribonucleic acid." RNA is made when the virus is active). A test of your "viral load" can measure this. This test tells your doctor the reason that you're feeling sick is because you have HIV.

First your doctor tests to see if you have HIV infection. Your blood is tested with an ELISA (enzyme-linked immunosorbent assay) test. If this test is positive for HIV, your blood is tested again with the Western blot test. If both tests are positive, you are diagnosed with HIV infection.

Three things show that a person who has HIV infection has developed AIDS. If any one or more of the following are present, the person has AIDS:

  • A CD4 cell count (discussed below) of less than 200
  • A CD4 cell percentage of less than 14%
  • An AIDS-indicator illness

An AIDS-indicator illness is a physician-diagnosed medical problem that occurs in people who have advanced HIV infection. About 25 medical problems are considered AIDS-indicator illnesses. They include conditions like Pneumocystis pneumonia, Kaposi's sarcoma and wasting syndrome. If a person who is infected with HIV gets an AIDS-indicator illness, that person has AIDS.

Does it help me to find out I have HIV at an early stage?

Yes. Right now, there is no cure for HIV. Your body can make antibodies and CD4 cells to slow down the progress of HIV, but they can't totally get rid of the virus. In fact, the very act of attacking the HIV infection may wear out your immune system in a short time.

However, treatment with HIV medicines (usually a combination of medicines called anti-retroviral drugs) can hold down the virus and keep your body's immune system strong for a longer time. That's why the U.S. Centers for Disease Control and Prevention (CDC) recommends early treatment of people who have HIV.

Are there HIV tests I can do at home?

Yes. The Home Access HIV-1 Test System is a collection kit that is used to collect a blood sample that is then mailed to a laboratory for testing. This test offers the advantage of privacy and anonymity. Another option is the OraQuick In-Home HIV test. This test involves swabbing the inside of your mouth. You do not have to collect your blood. Your results are ready within 20 minutes.

Should I use the home test or see my doctor?

Your doctor is concerned about you, your health and your privacy. If you want to be tested for HIV, you should see your doctor. He or she will help you decide whether you should be tested and will give you the support you need before and after the test. You don't get this type of support with home tests.

However, if you are afraid to talk with your doctor about HIV or to be tested, then the home collection test may be a good idea. If the test result is positive, you should see your doctor right away.

Remember, one negative test is not a guarantee that you don't have HIV or won't get it in the future. You should talk with your doctor and learn about ways to protect yourself from getting infected.


How to Recognize and Treat Acute HIV Syndrome by BL Perlmutter, M.D., Ph.D., JB Glaser, M.D., and SO Oyugi, M.D. (American Family Physician August 01, 1999,

Written by editorial staff

Reviewed/Updated: 04/14
Created: 01/96

Learn More About HIV and AIDS Diagnosis & Tests

Coping With an HIV Diagnosis

Plasma Viral Load Testing