HIV POSITIVE ? DEPENDS ON WHERE YOU LIVE...

THE HIV WESTERN BLOT TEST


The HIV Western blot consists of a thin nitrocellulose strip in which are embedded proteins claimed to be unique to HIV. Each protein is labelled with a 'p' followed by its molecular weight in thousands. Serum is added to the strip and if there are antibodies to a particular protein this band will 'light up'.

The HIV Western blot is not standardised and thus around the world different combinations of bands are considered positive. Hence a positive test in one country is not positive in another. An African would not be positive in Australia. A person from the MACS would not be positive anywhere in the world including Africa. Yet the HIV Western blot is considered to be highly specific and is considered synonymous with HIV infection.

According to data presented in Lundberg et al. (JAMA 260:674-679) when the US FDA criteria are used to interpret the HIV Western blot less than 50% of US AIDS patients are HIV positive whereas 10% of persons not at risk of AIDS are also positive by the same criteria.



AFR = Africa; AUS = Australia; FDA = US Food and Drug Administration; RCX = US Red Cross; CDC = US Center for Disease Control; CON = US Consortium for Retrovirus Serology Standardization; GER = Germany; UK = United Kingdom; FRA = France; MACS = US Multicenter AIDS Cohort Study 1983-1992.

Source: Val Turner

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