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The least expensive way to determine infection by the human immunodeficiency virus (HIV) is to test for the presence of HIV antibodies. Diagnostic testing is done in two stages, a screening test and a confirmatory test. The screening test is done on the initial submitted blood specimen, usually with an enzyme-linked immunoadsorbent assay (ELISA). If non-reactive for HIV antibodies, the screening test
is termed negative and no further testing is done. If reactive or inconclusive for HIV-antibodies, the screening test is repeated but this time with a confirmatory test such as the Western blot, immunoflourescent assay (IFA), or two different ELISA. If the confirmatory test is positive, the person likely has been infected with the HIV virus. Because of the serious nature of this diagnosis and the possibilities of test or laboratory error, persons who are diagnosed HIV positive are typically asked
to return at a later time for another independent diagnostic test.
In the United States, all persons who obtain the HIV test are expected to be counseled, both before the blood specimen is collected and after the results are known. The cost of such testing is high, usually ranging from about $50-75 for a negative test sequence to $150-175 for a positive test sequence. At federally-funded HIV testing centers in the United States, more than 95 percent of persons receiving blood tests are found to be negative. Thus the majority of funds spent by the US government for HIV testing goes to counseling and testing of uninfected persons.
An alternative to blood testing is to use saliva which also contains HIV antibodies, but at lower concentrations. Many investigators have studied and evaluated saliva tests and found them to be almost as valid as blood tests. Validity is measured by sensitivity, the percentage that measures positive with the test among those who truly have HIV antibodies, and specificity, the percentage
that measures negative with the test among those who truly do not have HIV antibodies.
Saliva tests have been recommended and used for population surveys, surveillance programs, and personal screening. The test would be especially useful for rapid screening since the saliva specimen could be tested in the doctor's office, a clinic or even in the privacy of a home, and, if the screening test is positive, the person would be referred to a health care provider for counseling and diagnostic testing with blood. With such a system, the percentage of persons at testing centers who are HIV negative would be greatly decreased, allowing more time and effort to be spent on those truly infected with the deadly virus. Such personal screening programs, however, are not yet legal in the United States because of the higher gravity associated with such systems by the FDA. The situation in the developing world is quite different in that there is a shortage of resources, the populations are less educated and not as accessible for follow-up as in the United States. It is extremely important therefore, to not apply the same criteria for testing adequacy in the developing world from an epidemiological and public health perspective as are applied in the United States.
A summary of all publications on saliva tests that have appeared to date is shown below:
REFERENCES
Please note that ImmunoScience's products are the subject of many US and International patent applications. This document does not convey any rights to develop, manufacture, use or sell anything described herein.
Collection HIV Authors Methods Antibody Assay HIV + HIV - Sensitifity (%) Specificity (%) Parry et. al., 1987 Free Drip GAC ELISA 43 10 100.0 100.0 Free Drip GACRIA 41 10 100.0 100.0 Johnson et. al, 1988 Free Drip Wellcome ELISA 196 460 100.0 99.8 Free Drip Wellcome ELISA 165 405 90.9 99.8 Free Drip Abbot ELISA 184 443 82.1 100.0 Free Drip Fujirebio PA 179 421 97.8 84.1 Holmstrom et al, 1990 Stimulated Drip Vironostika ELISA 36 14 97.2 100.0 O'Shea et al, 1990 Mouth Wash Abbot ELISA 22 -- 90.0 -- Archibald et al, 1991 Free Drip ASQ ELISA 21 -- 95.2 --- Behets et al, 1991 Free Drip Vironostika ELISA 145 313 97.9 100.0 Major et al, 1991 Not Stated Cambridge ELISA 119 429 98.3 100.0 Croffs et al, 1991 Salivette GACELISA 50 50 98.0 100.0 Salivette Abbot ELISA 50 50 88.0 100.0 Coates et al, 1991 Free Drip Cambridge EIA 11 323 100.0 100.0 Van den Akker et al, Free Drip Vironostika ELISA 79 115 100.0 100.0 1992 Klokke et al, 1991 Not Stated GACELISA 42 48 100.0 100.0 Gershy-Damet et al, Free Drip GACELISA 32 43 100.0 97.7 1992 Soto-Ramirez et al, 1992 Orasure Organon Teknika 356 1524 99.4 100.0 ELISA Frerichs et al, 1992 Omni-Sal Cambridge EIA 74 401 90.5 99.5 (Myanmar) Omni-Sal Cambridge EIA 74 400 94.6 99.5 (USA) Omni-Sal Cambridge EIA -- 1025 -- 100.0 (Myanmar) Omni-Sal Cambridge EIA -- 1025 -- 100.0 (USA) Thongcharoen et al, Free-Drip GACELISA 54 55 100.0 100.0 1992 Coveil et al, 1993 Salivette GACELISA 4 94 100.0 100.0 Hunt et al, 1993 Cotton swab GACELISA 8 214 100.0 100.0 Cotton swab GACRIA 18 273 94.4 100.0 Connell et al, 1993 Salivette GACELISA 50 127 100.0 100.0 Chamnarput et al, 1993 Free Drip DB ELISA HIV-1 100 100 94.4 89.0 Free Drip Genelavia 100 100 96.6 100.0 HIV-1/HIV-2 Free Drip Abbott Testpack 100 100 100.0 100.0 HIV-1/HIV-2 Free Drip Recombigen 100 100 100.0 100.0 HIV-1/HIV-2 RTD Holm-Hansen et al,1993 Orasure Abbot EIA 41 244 92.7 100.0 Orasure Abbot Testpack 44 243 100.0 100.0 Orasure Murex SUDS-1 36 230 97.2 100.0 Urgula et al, 1993 Not Stated Sandwich Indirect 50 50 96.0 100.0 Immummoassay Frerichs et al, 1994 Omni-Sal GACELISA 75 1405 100.0 99.9 Omni-Sal Cambridge EIA 75 1405 93.3 99.9 Omni-Sal Abbott HIVAB EIA 75 1405 98.7 99.1 Chassany et al, 1994 Omni-Sal GACELISA 115 451 100.0 100.0 Frerichs et al, 1994 Omni-Sal GACELISA 300 1654 100.0 100.0 Lu et al, 1994 Omni-Sal Abbott EIA 57 52 100.0 100.0 Omni-Sal Abbot Testpack 57 52 100.0 100.0 King et al, 1995 Omni-Sal Cambridge EIA 368 888 97.3 100.0 Emmoris et al, 1995 Orasure Abbott HIVAB EIA 195 198 100.0 100.0 Vall Mayans et al,1995 Omni-Sal GACELISA 133 153 100.0 98.7
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