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RAPID TESTS IN RESOURCE-LIMITED COUNTRIES: HIV testing is a critical component of the WHO Global AIDS and the PEPFAR programs. The recommendation is to perform a rapid screening test followed by a confirmatory rapid test in positives using an assay from an alternative commercial source. Concern for accuracy is based on the multiplicity of different clades and uncertain quality at test sites in the field. The "Rapid HIV Test Evaluation Work Group" from WHO and CDC has reported results with Determine, OraQuick, Uni-Gold and 6 other commercial sources (AIDS Res Hum Retrovir 2007;23:1491). With laboratory testing the median specificity was 100%. With field testing of 735,000 patients with a seroprevalence of 28%, the rate of concordance was 96.8-99.3% for positive specimens and 98.1-99.7% for negative specimens.
SALIVA TEST: OraSure (OraSure Technologies, Inc.; Bethlehem, Pa; 800-672-7873; www.orasure.com), is an FDA-approved device for collecting saliva and concentrating IgG for application of EIA tests for HIV antibody. The OraSure test is also available for screening blood. The OraSure test system for saliva can be used in the medical care setting and it is also available for home testing. The test consists of a specially treated pad used to swab the gums; the swab is then inserted into a vial for 20 minutes and read at 20 to 40 minutes. The amount of IgG obtained from saliva is far higher than in plasma and is well above the 0.5 mg/L level necessary for detection of HIV antibodies. Specimens from 26,066 patients showed a sensitivity of 99.24% and specificity of 99.89% compared to blood tests; there were 56 (0.22%) discordant results (AIDS 2006;20:1661). A cluster of 16 false positives brought the specificity down to 99% at one site (AIDS 2006;20:1655). Several subsequent reports have shown a high rate of false positives with provider read testing (Ann Intern Med 2008;149:130; AIDS Alert 2008;23:81; Intern J STD AIDS 2008;19:665; MMWR 2008;57:660). Potential advantages over standard serologic testing is the use of saliva instead of blood providing better patient acceptance, reduced risk of occupational exposure and availability in places that do not normally draw blood. However, there is no advantage if blood is to be drawn anyway and the high rate of false positives is bothersome. The recommendation is to use fingerstick blood initially or to confirm a positive oral fluid test with a rapid test using blood or standard serology. There is a proposal before the FDA to market an over-thecounter home test (NEJM 2006;354:437).
URINE TEST: Calypte HIV-1 Urine EIA (Calypte Biomedical Corp; Alameda, CA; 877-225-9783; www.calypte.com) is an FDA-approved screening EIA. This test can be adminis tered only by a physician, and positive results require confirmation by a standard serologic test with WB. Reported sensitivity is 99% (88/89), specificity is 94% (49/52) (Lancet 1991;337:183;
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