Department of Medical Physics, Royal Perth Hospital, Western Australia, 6001,
Valendar F Turner, John Papadimitriou, Barry Page, David Causer, Helman Alfonso, Sam Mhlongo, Todd Miller, Christian Fiala
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Diagnosing “HIV” infection in neonates
In his rapid response “Neonatal HIV”, 28 September 2004 Nicholas Bennett wrote “Mr Bartlett is quite right about the maternal antibodies being a problem. DNA-based PCR can be used (as opposed to the less specific but more sensitive RT-PCR of viral load) as well as viral culture, but that latter technique takes several weeks to get a result”.
Nicholas Bennett’s view in regard to the use of PCR for the diagnosis of neonatal “HIV” infection is not shared by other British researchers. In their view DNA based PCR is less specific than the antibody tests. According to Philip Mortimer,” Other diagnostic methods, e.g. p24 antigen testing, and proviral DNA and RNA amplification exist, but these innovations in HIV diagnosis need to be matched against the anti-HIV [ANTIBODY] test.1 According to researchers from the University of London, “The use of polymerase chain reaction (PCR) for the diagnosis of HIV infection is becoming more widespread and although not yet entirely reliable compared with serology…"2 Yet another British researcher states “Those laboratories which undertake HIV screening and confirmation assays understand fully the technical problems associated with PCR and other amplification assays and it is precisely for those reasons that PCR is NOT used as a confirmatory assay (as discussions with any competent virologist would have informed them)”3 (emphasis in original). Researchers from the USA wrote “Our investigation produced two main findings. First, the false -positive and false-negative rates of PCR that we determined are too high to warrant a broader role for PCR in either routine screening or in the confirmation of diagnosis of HIV infection”.4
Nicholas Bennett wrote “Negative infants are followed up until their antibodies disappear, usually at 9 months”.
In regard to maternal antibodies disappearing by 9 months would Nicholas Bennett please study the findings of the European Collaborative Study and the Ariel Project, summarised in our monograph “Mother to Child Transmission of HIV and its Prevention with AZT and Nevirapine”- pages 44- 45 (Reference 5). In brief the argument is as follows: The European Collaborative Group Study,6 is the only study providing a detailed analysis of the post partum loss of infant “HIV” seropositivity. The authors reported approximately 23% of children became seronegative between birth and 9 months. However, 59% became seronegative between 9 and 22 months. Since the latter cannot be due to loss of maternal antibodies, the only explanation is that either: (i) the antibody test is non- specific or; (ii) the children managed to clear "HIV" infection without treatment. If 23% of children test positive because of maternal antibodies, and in 59% the test is non-specific, how can one be certain that the remaining 18% of children will not also serorevert after 22 months? If the test is non-specific in 59% of children one must also question whether such a test can be “extraordinarily accurate” when applied to the diagnosis of HIV infection of mothers, as well as to fathers and adults in the general population. See graph at www.theperthgroup.com/PRESENTATIONS/EuroStudyGp.ppt
Could Nicholas Bennett please let us know if he agrees with our interpretation of these data. If not could he please provide an alternative explanation.
1. Mortimer PP. Ten years of laboratory diagnosis of HIV: how accurate is it now? J Antimicrob Chemother 1996;37:B. 27-32.
2. Boriskin YS, Booth JC, Roberts MM, Carrington D, Coates ARM. HIV primers can amplify sequences of human satellite DNA. AIDS 1994;8:709-711.
3. Chrystie IL. Screening of pregnant women: the case against. Pract Midwife 1999;2:38-39.
4. Owens DK, Holodniy M, Garber AM, Scott J, Sonnad S, Moses L, et al. Polymerase chain reaction for the diagnosis of HIV infection in adults. A meta-analysis with recommendations for clinical practice and study design. Ann Int Med 1996;124:803-15.
5. Papadopulos-Eleopulos E, Turner VF, Papadimitriou JM, Alfonso H, Page BAP, Causer D, et al. Mother to Child Transmission of HIV and its Prevention with ATZ and Nevirapine. Perth: The Perth Group, 2001. http://www.theperthgroup.com/MONOGRAPH/MTCTJuly24.pdf
6. Mother-to-child transmission of HIV infection. The European Collaborative Study. Lancet 1988;ii(8619):1039-43.
Competing interests: None declared