Re: Repeat, the "HIV" antibody tests are not diagnostic 21 October 2004
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Peter J Flegg,
Physician
Blackpool, UK

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Re: Re: Repeat, the "HIV" antibody tests are not diagnostic

It would be useful if the Perth Group did not “cut and paste” material in their rapid responses, since this seems to plays havoc with the formatting, but more crucially leaves orphaned references, making it difficult to cross-check their source material (something that is necessary, considering their propensity for misinterpreting the work of others). The recent offering in “Repeat, the "HIV" antibody tests are not diagnostic”, 20th October, provides just one example. Source material for their statements on infant serology comes directly from their un-peer reviewed monograph “"Mother to Child Transmission of HIV and its Prevention with AZT and Nevirapine" (2001).

The cause of the Perth Group’s misconceptions seems to be their interpretation of the timing of maternal HIV antibody disappearance, as Nick Bennett has pointed out. The European collaborative study (1988) judge that 15 months is an appropriate time for this to have happened by, rather than 9 months. Why this has become such a burning issue in the eyes of the Perth Group is hard to say – does it really matter if a study shows it takes longer than 9 months for some maternal antibody to decline? In practice, not really, since alternative methods exist for confirming the presence of HIV. Many other maternal antibody levels may take more than a year to decline, such as measles antibody.

The fact that one researcher using a particular assay showed a more rapid decline in antibody levels does not mean that any child with detectable antibody after 9 months is infected with HIV (particularly if they then lose antibody in the next 6 months). (Oh, and by the way, it is an IgG (letter I) assay and not a 1gG (number one) assay as the Perth Group persists in calling it).

Ref: Mother-to-child transmission of HIV infection. The European Collaborative Study. Lancet 1988: 1039-43.

Competing interests: None declared