Introduction
Madam, Recently a lady aged 32 in her second pregnancy tested HIV antibody positive by the ELISA (enzyme-linked immunosorbent assay) screening test, but negative by the Western Blot assessment (Letters to the Editor, Dawn April 5, 2004), which is a definitive confirmatory test, except if one is infected with HIV during the 3-month window period. That approximately 1.26% of ELISA tests give positive results which are proven false by the Western Blot is well documented in literature, which should be noted by medical practitioners and labs in the country that conduct screening tests in order to counteract traumatic social impasse. ELISA can be HIV antibody false-positive in the uninfected for several reasons, because each individual in life is exposed to plethora of foreign antigens which can initiate poorly-understood cross-reactions1; these include, among others, naturally occurring antibodies, autoimmune disease (e.g. SLE and rheumatoid arthritis), pregnancy in multiparous women2, TB and leprosy, malaria, Flu and upper respiratory infections3, blood transfusions, 13% of alcoholics with hepatitis, liver diseases1, 4% of hemodialysis patients and 19% of those with hemophilia1, or noteworthy, even following recent vaccinations for hepatitis B4, tetanus, rabies and influenza.5
Essa M. Abdulla
Dr. Essa's Lab & Diagnostic Center, Karachi.
References
1. Bylund D, Ziegner U, Hooper D. Review of testing for HIV. Clin Lab Med 1992;12:305-33.
2. Steckelberg JM, Cockerill F. Serological testing for HIV antibodies. Mayo Clin Proc 1988;63:373.
3. Challakere K, Rapaport M. False-positive HIV-1 ELISA results in low-risk subjects. West J Med 1993;159:214-15.
4. Lee D, Eby W, Molinaro G. HIV false positiveity after hepatitis B vaccination. Lancet 1992;339:1060.
5. Mackenzie WR, Davis JP, Peterson DE, Hibbard AJ, Becker G, Zarvan BS. Multiple false-positive serologic tests for HIV, HTLV-1 and hepatitis C following influenza vaccination. JAMA 1992;268:1015-17.
