Laboratory testing for HIV
is a two step process.
-
First is the screening immunoabsorbant
assay (ELISA).
- Now have and oral HIV screening test
for saliva.
-
If the sample is positive, the
more specific Western blot is done.
Although the ELISA screening
test is pretty reliable (99%), there is a low percentage error rate.
False Positives
-
Antibody against human tissues
(smooth muscle, mitochondria, T-Cells)
-
Anti-Hepatitis A IgM
-
Anti-Hepatitis B core IgM
-
Positive Syphilis serology
-
advanced liver disease
-
Renal failure
-
Cross reacting viruses (HIV-2,
HTLV)
-
Passive acquired antibody (transplacenta,
immunoglobulin)
-
Malignancy
|
False Negatives
-
B-Cell dysfunction (severe HIV
infection)
-
Hypogammaglogulinemia
-
Test drawn during "window" period
-
Malignancy
-
Immunosuppressive therapy
-
Bone marrow transplant
-
Heat inactivation of antibody
in sample while waiting for test to be performed.
|
Mr. Baldwin's ELISA screening
test is positive. But before saying anything, we need to be sure by checking
the Western Blot |