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| Farber | HIV tests detect footprints, never the animal itself. These footprints, antibodies, are identified by means of molecular protein weights, and were limited to two in 1984, when the first test was developed and patented, but over the years expanded to include many proteins previously not associated with HIV. Like most Americans, Hafford thought that a single HIV-positive test meant that she “had” HIV—a surefire death sentence. But a majority of HIV-positive tests, when retested, come back indeterminate or negative. In many cases, different results emerge from the same blood tested in different labs. There are currently at least eleven different criteria for how many and what proteins at which band density signal “positive.” The most stringent criteria (four bands) are upheld in Australia and France; the least stringent (two bands), in Africa, where an HIV test is not even required as part of an AIDS diagnosis. The U.S. standard is three reactive bands. It has been pointed out that a person could revert to being HIV negative simply by buying a plane ticket from Uganda to Australia. |
| Gallo | In footnote one, Farber makes various false statements about HIV tests. She comments that HIV tests are not even required for an AIDS diagnosis in Africa. She also claims most HIV tests come back indeterminate or negative when redone. She supplies no references. Most people in the industrialised world, as well as many developing countries, have at least two different HIV antibody tests to confirm they are HIV-positive, as part of the HIV testing protocol. HIV tests are highly accurate. It is false that when most people are retested they test indeterminate or negative. Even the risk of a single HIV ELISA test giving a false positive is less than 1% with today's tests. HIV tests are required for an AIDS diagnosis in South Africa. They are also standard in Botswana, Kenya, Uganda and many other clinics throughout Africa. An AIDS diagnosis cannot be considered definitive without an HIV test. Farber's comment about hopping on a plane from Uganda to Australia to change HIV diagnosis is simply silly hyperbole. |
| RA | HIV not required for AIDS in Africa Farber is perfectly correct that an HIV test is not required in Africa. Quoting from the WHO’s 1994 AIDS Case Definition (the most recent WHO definition listed at who.int/hiv/strategic/surveillance/definitions/en): For the purposes of AIDS surveillance an adult or adolescent (>12 years of age) is considered to have AIDS if at least 2 of the following major signs are present in combination with at least 1 of the minor signs listed below, and if these signs are not known to be due to a condition unrelated to HIV infection.Major signs…Advantages of the WHO case definition for AIDS surveillance are that it is simple to use and inexpensive since it does not rely on HIV serological [antibody] testing. Limitations of this case definition are its relatively low sensitivity [i.e. it misses people with AIDS] and its low specificity [i.e. it is prone to false positive diagnoses] particularly with respect to tuberculosis… It is also not completely correct to note that HIV tests are required for an AIDS diagnosis in South Africa. It is true that HIV testing is performed, but to a much lower standard. A nationwide survey of South Africans [1], relied on two positive ELISA tests, while in North America generally three ELISA tests are performed, followed by a confirmatory test such as Western Blot. This will obviously result in more false positive test results. Another South African survey [2] used only a single ELISA test. Accuracy of HIV tests Since 1985 different sorts of biochemical tests have been licensed and used in laboratory-based clinical procedures known as ‘algorithms’. These algorithms are used by public health authorities to identify what have been thought of as antibodies to proteins of the human immunodeficiency virus (HIV). Case definitions by public health authorities (e.g. CDC) of the Acquired Immunodeficiency Syndrome (AIDS) refer to the results of these HIV antibody tests in order to define AIDS. These biochemical antibody tests were developed from the original laboratory algorithms first used to identify what were thought of as antibodies to HIV proteins. Two common antibody-based methodologies used today are the enzyme-linked immunosorbent assay (ELISA) and the Western blot (WB), both used for the screening of human populations for ‘HIV antibodies’. Manufacturer literature document that these tests produce false or indeterminate results because the interpretation of the test result is based solely upon the statistical probability of infection as opposed to the positive/negative isolation of a biological entity. In addition the biochemical laboratory identification in these tests of what are thought of as HIV proteins is known to be highly problematic, time-intensive and so requires ‘surrogate’ techniques. This is because direct isolation of the biological entity of any retrovirus in the laboratory is not possible. In other words, no HIV test has ever had its results correlated with detection of actual virus, so nobody actually knows if any positive HIV results are true positives. Across the world, public health officials use different algorithms for testing of humans for the presence of what are thought of as ‘HIV proteins’. These algorithms aim to balance test specificity and sensitivity by using variations of the original test methodologies and differing commercially available tests. However, they all are premised upon the health professional’s perception of the ‘exposure risk’ of the client/patient, which is determined during pre-test dialogue in the clinic: how the test subject is positioned by the professional as ‘high’/‘low’ risk within a hierarchy of exposure categories. This means that the results of these tests are not based upon the identification of any biological retroviral entity, or even the biochemical reaction in the laboratory, but they are based on interpretation of the laboratory test signal in relation to the client’s/patient’s perceived probability of infection. The interpretation of indeterminate results is problematic given the possibility of false results, which are ruled out by estimating the risk of exposure (‘window period’) and the seroprevalence in the ‘risk population’ of the test subject based on what ‘risk behaviour’ the subject discloses to the health professional or which the latter surmises during the clinic interview. Since 1985, experience with these test algorithms has shown that the interpretation of the test ‘result’ is not wholly ‘objective’ i.e. the interpretation of the test result is not determined by what happens in the laboratory because it relies upon classifying the test subject as being ‘at risk’ during pre-test dialogue rather than the biochemical signal reaction in the ELISA or WB. This sort of information is generally not known by many health professionals who do not understand how ‘HIV tests’ are conducted and the premise of probability upon which they are based. An example of problems with the tests comes from the 1980s, before the algorithms were fully standardized, at a time when intermediate results were still sometimes reported. The researchers studying a large low-risk population stated that “Although exact percentages were not routinely recorded and calculated, approximately 1% of all initial screening ELISA were reactive [positive], 50% of repeat [second] ELISAs were reactive, and 30% to 40% of first Western blot assays were reactive and diagnostic” [3]. Today, algorithms for HIV testing do not specify duplicate Western blot assays, so many false positives, perhaps still the majority of tests, go unrecognized. It is also important to note that standards vary around the world, especially for interpretation of the Western Blot ‘Confirmatory’ test. Eleven radically different interpretations have been documented for use in different countries and by different organizations. |
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