HIV, or human immunodeficiency virus, is a sexually transmitted disease that results in the deterioration of the person's immune system. While HIV does have visible symptoms, the only way to diagnose an HIV infection is through a blood test. The ELISA/Western blot combination is the most effective, but a white blood differential is another option.
ELISA/Western Blot
According to the National Institutes of Health, the ELISA test requires a blood sample taken from either the inside of the elbow or the back of the hand. Before the blood is drawn, an antiseptic wipe is used to clean the injection site. An elastic band may be put around the upper arm to increase pressure and ease drawing the blood. After the blood is collected, it is stored in an airtight vial. Then the blood sample will be screened for the presence of anti-HIV antibodies. If the ELISA test comes back positive, it is then followed by a Western blot. The Western blot will be able to confirm the presence of HIV.
Possible Difficulties
False positives can occur from the ELISA test. Lyme disease, syphilis and lupus can result in a positive on the ELISA, but the false positives will be ruled out by the Western blot. Even if the patient has HIV, the test can come back negative if the infection was recent. High-risk persons should have an HIV test every 6 months.
Blood Differential
According to the National Institutes of Health, another option to test for HIV is the blood differential, though this is not an HIV-specific test. Like the ELISA test, blood is drawn and put into an airtight vial. A drop of blood is smeared on a glass slide, and then a special dye is added that detects white blood cells. Five types of white blood cells are detected with this dye: lymphocytes, neutrophils, monocytes, eosinophils and basophils. A decreased percentage of lymphocytes can indicate an HIV infection. While a blood differential can note the abnormality, it cannot be used alone to diagnose HIV.
