Why the "AIDS Test" doesn't work in Africa

Townsend Letter for Doctors and Patients,  April, 2002  by Christine Johnson

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In light of the summer of 2000 events at the 13th International AIDS conference in Durban, and South African President Thabo Mbeki's refusal to adhere to the "conventional wisdom" on AIDS, it has become even more crucial to reevaluate all aspects of AIDS in Africa.

It is widely believed that Africa is being devastated by a plague of AIDS. This is in spite of the fact that, according to the World Health Organization's (WHO) Weekly Epidemiological Record, 19 years' worth of AIDS cases for the entire continent of Africa has amounted to only 876,009. (In the US, more people than this die in one year of heart disease.) Africa is generally blamed as being the origin of AIDS, yet statistics point towards a more likely source of this disease: The United States.

It was not until 1997 that the cumulative number of AIDS cases in Africa surpassed those in the United States. The most current stats (as of November 2000) show that the cumulative tally stands at Africa 876,009 and the United States 733,374--not much of a difference considering WHO's estimate that 25.3 million Sub-Saharan Africans have HIV/AIDS, whereas in the United States it is well below one million. Why this huge discrepancy? The main reason is that lots of Africans test positive on HIV antibody tests -- while very few Americans do - and few HIV-positive people in any country go on to develop AIDS.

Researchers originally began looking to Africa as the source of AIDS for three rather feeble reasons: (21) 1) Robert Gallo's discredited theory that AIDS was caused by HTLV-1, another retrovirus similar to HIV, and thought to be endemic in Africa; 2) the prevalence of Kaposi's sarcoma in Africa (even though Kaposi's sarcoma was a new disease in American gay men, it had existed in Africa since ancient times, and hence could not indicate a brand-new disease there); and 3) a small number of AIDS patients of African origin who were living in Europe.

When researchers began taking HIV antibody test kits to Africa around 1985, they immediately found verification of the above ideas. Small groups of Africans were tested and found to be positive on these tests, and these numbers were extrapolated to the entire population. On this basis, and although only a few thousand AIDS cases had been reported in Africa at that time, the WHO immediately began estimating that millions of Africans were infected with HIV and that Africa would have to contend with an imminent plague.

In the mid-80s when HIV antibody tests first became available, it immediately became apparent that there were problems associated with using these tests in the African population. (1-5) In 1985, Hunsmann found that positive HIV (then called HTLV-III) ELISA tests had a low frequency of confirmation using a different type of antibody test, the immunoprecipitation method. This led him to question the specificity of ELISA in African blood samples. (1)

Biggar found correlations between positive HIV antibody tests and age and poverty. (2) He also found correlations with malaria and parasitic diseases in Africans (but not in Asians or South Americans). Labius Mutanda of the Ugandan Public Health Service and guest lecturer at St. Louis University (US) in 1991 reported that "existing ELISA and Western Blot assays may not always be able to reliably ascertain HIV infection in many African individuals." (3) Mutanda told me that his experience with both ELISA and Western Blot in Uganda was that often an individual could be positive if tested with the test kit from one manufacturer and negative if tested with the kit of a different manufacturer.

Serious questions have arisen as to whether HIV antibody tests are specific in any population, (6) although mainstream AIDS researchers still believe they are accurate, and considerations of test failure in Africa have never prevented the tests from being used there for many purposes including estimating HIV infections. Mulder in 1994 demonstrated that HIV positive Africans died at a much greater rate than HIV-negative Africans, and offered this as definitive proof that HIV causes AIDS. (7) In reality, the only thing Mulder proved was the utility of HIV antibody tests when employed as generalized indicators that something is wrong, i.e., they can be used as surrogate markers of AIDS risk.

The ELISA test contains a mixture of broken-up HIV proteins called a "whole viral lysate." In theory, if a person's blood contains any HIV antibodies, the ELISA will react. The Western Blot is more sophisticated (and much more expensive). The HIV proteins are separated into bands on a strip. That way, if any antibodies cause a reaction, it can be determined exactly which HIV protein they are reacting to. The most important HIV proteins are p24, p32, gp4l, gpl2O, and gp160.

In the US, ELISA is considered to be very inaccurate, and no diagnosis of HIV infection is allowed to be made without a Western Blot (considered to be more accurate) as confirmation. Interestingly, in the UK, just the opposite is true and Western Blots are considered to be inaccurate!