MedlinePlus notes that in 2008, about 3.4 million people in the world had human immunodeficiency virus, or HIV, or acquired immunodeficiency syndrome, or AIDS. The virus, which spreads through sexual contact or needle exchange or from mother to child, weakens patients' immune systems. Over time, HIV progresses into AIDS. Certain diagnostic criteria exist for AIDS; these help doctors determine the appropriate treatment measures.
Time Frame
Patients can have an HIV infection for many years before it develops into AIDS. The MayoClinic.com explains that patients may have no symptoms for years, with the virus progressing into AIDS 10 years later. Even when a person becomes infected with HIV, it may not show up on an HIV blood test for some time. MedlinePlus points out that it may take up to three months for a blood test to come back positive after exposure to the virus.
CD4 Cell Count
A major criterion for AIDS diagnosis is the patient's CD4 cell count. A type of immune cell, the CD4 cells become affected by the virus. As the disease progresses, the number of CD4 cells diminishes. MedlinePlus explains that a person may receive a diagnosis of AIDS if he has a CD4 cell count of under 200 cells/mm3, even if he does not have an opportunistic infection. The University of California, San Francisco, Medical Center points out that healthy people have a cell count of about 1,000 cells/mm3.
Opportunistic Infections
Another AIDS diagnostic criterion is opportunistic infections, which AIDS patients develop as their immune system gets weaker. Opportunistic infections occur in relation to the current CD4 count. For example, MedlinePlus notes that with a CD4 cell count of below 300 cells/mm3, patients may develop vaginal thrush; with a CD4 cell count of below 100 cells/mm3, patients may develop AIDS dementia. The University of California, San Francisco, Medical Center lists several types of opportunistic infections that AIDS patients may have that qualify them for a diagnosis. Examples include wasting syndrome, cytomegalovirus, Kaposi's sarcoma, mycobacterium tuberculosis and recurrent pneumonia.
Testing
Doctors perform certain tests when diagnosing AIDS. For example, the doctor may draw blood samples to do a CD4 count or to test the amount of the virus in the blood. The MayoClinic.com explains that people who have higher viral loads in their blood do not do as well as other patients. Another diagnostic test is a drug resistance test, which indicates if the antiretroviral medications used to treat HIV and AIDS will benefit the patient. The diagnostic testing may also include tests for specific opportunistic infections.
Considerations
While antiretroviral medications may help suppress the virus' replication, they do not cure the disease. MedlinePlus points out that AIDS is the sixth most common cause of death among 25- to 44-year-old Americans, although this is a drop from the number one spot in 1995. Even once the immune system becomes severely compromised, the antiretroviral medications may still help patients. The MayoClinic.com adds that antiretroviral treatment should begin when the CD4 count drops below 500 cells/mm3.
