Infectious Disease Postdoc Clinician
Department of Pediatrics, University Hospital, Syracuse, NY
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In reply to Anita Allen:
One wonders why the same test inserts are repeatedly quoted: e.g. the first ever HIV antibody test which states, correctly, that at the time the test was created (and the paperwork written up) no other standard existed for establishing infection. Also quoting a monitoring test that states it cannot be used for screening purposes. Why not look at some of the other tests in their correct context?
The COBAS ampliscreen test (A PCR-based donor screening test) for example includes the following language.
"The COBAS AmpliScreen™ HIV-1 Test, version 1.5 (v1.5) is a qualitative in vitro test for the direct detection of Human Immunodeficiency Virus Type 1 (HIV -1) RNA in human plasma."
"This product is intended for use as a donor screening test to detect HIV-1 RNA in plasma samples from individual human donors, including donors of Whole Blood and blood components, Source Plasma and other living donors."
"Human Immunodeficiency Virus (HIV-1) is the etiologic agent of Acquired Immunodeficiency Syndrome (AIDS). HIV-1 infection can be transmitted by sexual contact, exposure to infected blood or blood products, or by an infected mother to the fetus."
Rather more concrete language, one must agree.
The Vironostika package insert (an ELISA-based test) states:
"The Vironostika HIV-1 Plus O Microelisa System is intended for use as an aid in diagnosis of infection with HIV-1."
"Published data indicate a strong correlation between the acquired immunodeficiency syndrome (AIDS) and a retrovirus referred to as Human Immunodeficiency Virus (HIV).<snip> Both HIV serotypes have been isolated from patients with AIDS and AIDS- related complex (ARC), as well as from apparently healthy individuals at high risk for AIDS."
The Reveal Rapid Antibody test states:
"Human Immunodeficiency Virus (HIV) causes Acquired Immune Deficiency Syndrome (AIDS)."
"The Reveal™ Rapid HIV -1 Antibody Test is intended for use as a point-of-care test to aid in the diagnosis of infection with HIV-1."
The Cambridge Biotech Western Blot kit states:
"The Enzyme-Linked lmmunosorbent Blot Technique (“Western Blot”), has been used to detect antibodies to Human lmmunodeficiency Virus Type 1 (HIV -l), which has been recognized as the etiological agent of the Acquired lmmunodeficiencv Syndrome (AIDS)."
The throwaway line that "how can epidemiologic studies be consider as scientific evidence?" amazes me, since if we are to reject all such standards then we have no need to perform clinical trials on drugs! They are, after all, an epidemiological study - just with an intervention rather than purely observational. The papers cited in any case are not epidemiological, but rather virus culture observations.
Also Ms Allen seems to confuse the viral load tests with the CD4 T cell counts, which are entirely different. A CD4 count that low is almost exclusively seen in HIV infection, but she is wrong when she states that HIV infection is inferred. Serological and viral load testing is done prior to commencing antivirals (which would be indicated at that low a CD4 count, because the risk of an opportunistic infection in people in the same situation historically was so high). She also says that the tests are either diagnostic or research, when third and fourth roles exist - those of screening and monitoring. It is these latter roles that the PCR- based tests are largely used in.
Ultimately of course no test is ever going to diagnose anything - that decision rests with the clinician, using the patients history, examination, and test results. Faced with the knowledge that a person has anti-HIV-1 antibodies, and knowing that HIV is a life-long infection, the obvious conclusion (and diagnosis) is of HIV infection.
I hope this clears up some of the points she made.
Nick Bennett email@example.com
Competing interests: None declared