Several tests can be administered to determine whether or not a person has been exposed to the HIV/AIDS virus and to what stage the disease has progressed.  When a person is infected with HIV, different substances, such as proteins and antibodies, appear in the blood. 

The following tests help detect these substances, and verify whether or not a person has HIV:


The first step of an HIV test, Elisa, detects the presence of HIV antibodies in the blood.  If the test is positive, a second step is run to confirm the results of the first test.

Western Blot

This second step is used to confirm a positive Elisa test result. This test detects specific protein bands that are present in an HIV infected person. 


This final test detects specific DNA and RNA sequences that indicate the presence of HIV in an infected person.

Once a positive HIV diagnosis has been determined, there are several steps to be taken to determine at what stage of HIV or AIDS a victim has reached.

CD4 Count

CD4 cells are a specific type of white blood cell that are targeted and destroyed by the HIV virus.  A healthy person has a CD4 count well above 500.  Therefore, infection can be determined by a CD4 count of less than 200 cells per cubic millimeter of blood, the level at which the immune system can no longer protect a person from AIDS-defining illnesses and infections (listed below).

Viral Load

This test measures the amount of virus in your blood.  The lower the viral load, the easier it is to combat the illness.

Drug Resistance

The drug resistance test is administered to determine if your strain of HIV is resistant to any anti-HIV medication.

AIDS-Defining Illnesses

AIDS can be determined by the presence of one of many opportunistic illnesses or infections.  Those illnesses said to be AIDS defining include:

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