During a medical check-up for a new insurance policy, a 60-year-old grandmother is found to be positive in the ELISA screening test for antibodies against HIV-1. She has no known risk factors for exposure to the virus. Which of the following is the most appropriate next step?
|A||Immediately begin therapy with azidothymidine.|
|B||Perform the screening test a second time.|
|C||Request that a blood culture be done by the lab.|
|D||Tell the patient that she is likely to develop AIDS.|
a. Because HIV cannot be safely isolated and grown in the standard medical center diagnostic laboratory, diagnosis of HIV infections relies on detection of antibodies against the virus.
b. The standard screening test is done by ELISA (enzyme-linked immunosorbent assay).
c. ELISA test formats are quite reliable and accurate and can be used for antibody or antigen detection. By definition, however, screening tests are not 100 percent accurate for sensitivity and specificity.
d. HIV infection, especially, is a tragic infection that requires utmost accuracy in laboratory diagnosis results to aid the physician in counseling the involved patient and family.
e. Under the conditions described in Question, no known risk factors for HIV contact are claimed or identified.
f. For this situation and any other requiring diagnostic laboratory testing for HIV infection, extra effort is taken to ensure accuracy and correct results.
g. Because it is widely accepted that HIV ELISA screening is not 100 percent sensitive and specific (about 98% accurate, however), a second blood sample is collected for retesting by ELISA.
h. If both ELISA results are positive, a second confirming test is done. This is usually a Western blot technique. If the Western blot test is positive, then HIV infection is confirmed and related to the patient.