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Monday, July 15, 2002.. According UNAIDS, "anonymous blood specimens left over from these tests [routine prenatal care tests] are tested for antibodies to HIV," a ritual that usually takes place once a year. The results are fed into a computer model that uses "simple back-calculation procedures" and knowledge of "the well-known natural course of HIV infection" to produce statistics for the continent In other words, AIDS researchers descend on selected clinics, remove the leftover blood samples and screen them for traces of HIV The results are forwarded to Geneva and fed into a computer program called Epi-model: If a given number of pregnant women are HIV-positive, the formula says, then a certain percentage of all adults and children are presumed to be infected, too. And if that many people are infected, it follows that a percentage of them must have died. Hence, when UNAIDS announces 14 million Africans have succumbed to AIDS, it does not mean 14 million infected bodies have been counted. It means that 14 million people have theoretically died, some of them unseen in Africa's swamps, shantytowns and vast swaths of terra incognita. Most of Africa is too disorganized to reliably track death rates and compare the actual numbers to the UNAIDS estimates, but South Africa, where the author lives, does track death rates: It therefore seemed to me that checking the number of registered deaths in South Africa was the surest way of assessing the statistics from Geneva, so I dug out the figures. Geneva's computer models suggested that AIDS deaths here had tripled in three years, surging from 80,000-odd in 1996 to 250,000 in 1999. But no such rise was discernable in total registered deaths, which went from 294,703 to 343,535 within roughly the same period. The discrepancy was so large that I wrote to make absolutely sure I had understood these numbers correctly..... Between these extremes lay a gray area populated by local experts such as Stephen Kramer, manager of insurance giant Metropolitan's AIDS Research Unit, whose own computer model shows AIDS deaths at about one-third Geneva's estimates. In addition to confounding the issue with statistical voodoo, the AIDS numbers also may be inflated due to the testing methods themselves. Instead of confirming a postive ELISA test with the Western blot testing , the AIDS numbers are based on only one ELISA test. This test is not a specific test for AIDS, it’s a test for antibodies to AIDS, and it can be confounded by antibodies to other diseases, say malaria or tuberculosis, both of which are also running rampant in Africa: It seemed something was confounding the tests, and the prime suspect was plasmodium falciparum, one of the parasites that causes malaria: Of the twenty-one subjects who tested positive, sixteen had had recent malaria infections and huge levels of antibody in their veins. The researchers tried an experiment: They formulated a preparation that absorbed the malaria antibodies, treated the blood samples with it, then retested them. Eighty percent of the suspected HIV infections vanished. ....Back in 1994, Max Essex, head of the Harvard AIDS Institute, and some collegues of his observed a "very high" (sixty-three percent) rate of ELISA false positives among lepers in central Africa. Mystified, they probed deeper and pinpointed the cause: two cross-reacting antigens, one of which, lipoarabinomannan, or LAM, also occurs in the organism that causes TB. This prompted Essex and his collaborators to warn that ELISA results should be "interpreted with caution" in areas where HIV and TB were co-endemic. Indeed, they speculated that existing antibody tests "may not be sufficient for HIV diagnosis" in settings where TB and related diseases are commonplace. Essex was not alone in warning us that antibody tests can be confused by diseases and conditions having nothing to do with HIV and AIDS. An article in the Journal of the American Medical Association in 1996 said that "false-positive results can be caused by nonspecific reactions in persons with immunologic disturbances (e.g., systemic lupus erythematosus or rheumatiod arthritis), multiple transfusions or recent influenza or rabies vaccination.... To prevent the serious consequensces of a false-positive diagnosis of HIV infection, confirmation of positive ELISA results is necessary.... In practice, false-positive diagnoses can result form contaminated or mislabeled specimens, cross-reacting antibodies, failure to perform confirmatory tests.... or misunderstanding of reported results by clinicians or patients." These are not the only factors that can cause false positives. How about pregnancy? The U.S. National Institutes of Health states that multiple pregnancy can confuse HIV tests. In the past few years, similar claims have been made for measles, dengue fever, Ebola, Marburg and malaria (again). The author talked to a UNAIDS advisor who naively told him that countries with high false postives would report it to the agency. The author thinks otherwise: High AIDS numbers are not entirely undesirable in poverty-stricken African countries. High numbers mean deepening crisis, and crisis typically generates cash. The results are now manifest: planeloads of safari scientists flying in to oversee research projects or cutting-edge interventions, and bringing with them huge inflows of foreign currency - about $1 billion a year in AIDS-related funding, and most of it destined for the countries with the highest numbers of infected citizens. On the ground, these dollars translate into patronage for politicians and good jobs for their struggling constituents. In Uganda, an AIDS counselor earns twenty times more than a schoolteacher. In Tanzania. AIDS doctors can increase their income just by saving the hard-currency per diums they earn while attending international conferences. Here in South Africa, entrepreneurs are piling into the AIDS business at an astonishing rate, setting up consultancies, selling herbal immune boosters and vitamin supplements, devising new insurance products, distributing condoms, staging benefits, forming theater troupes that take the AIDS prevention message into schools. A friend of mine is co-producing a slew of TV documentaries about AIDS, all for foreign markets. Another friend has got his fingers crossed, since his agency is on the shortlist to land a $6 million safe-sex ad campaign. An AIDS counselor earns twenty times more than a schoolteacher? Could this be true? The damage that can be done by politicizing a disease never ceases to amaze. At least one South African AIDS activist knows what needs to be done to help stem the African problem: "There's a place for AIDS drugs and prevention campaigns," he says, "but it's not the only answer. We need to roll out clean water and proper sanitation. Do something about nutrition. Put in some basic health infrastructure. Develop effective drugs for malaria and TB and get them to everyone who needs them." But will the AIDS activists listen? posted by Sydney on 7/15/2002 07:20:00 AM 0 comments 0 Comments: |
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