AIDS - Diagnosis

HIV infection can be difficult to diagnosis. Its symptoms are often similar to those of other diseases. To aid doctors in diagnosing the disease, the CDC has drawn up a list of thirty-four conditions to look for. These conditions can be used to decide which of three categories a patient falls into. Those categories include the following:

• Definite diagnosis with or without laboratory evidence of HIV infection.
• Definite diagnosis with laboratory evidence of HIV infection.
• Probable diagnosis with laboratory evidence of HIV infection.

Many symptoms discovered during a physical examination suggest the possibility of HIV infection. Some of these are more reliable predictors than others. Hairy leukoplakia of the tongue and KS are examples of strong predictors of HIV infection.

The presence of HIV infection is always confirmed with one or more blood tests. The first of these tests is called an enzyme-linked immunosorbent assay (ELISA). A person who tests positive on an ELISA test is then given a second blood test. That test is called a Western blot or immunofluorescence (pronounced im-yuh-no-flur-ES-uhnts) assay (IFA). A combination of the ELISA and Western blot test is 99.9 percent accurate in diagnosing HIV infection. In rare cases where doubt still exists, a third test is available, the polymerase (pronounced POL-uh-muh-raze) chain reaction (PCR) test.

A variety of tests are available to track the course of HIV infection. Among these are blood counts that measure the number and kind of white blood cells present. Tests also track the development of opportunistic infections, such as damage to the nervous system, and cancers.