Replies

Unreliable Tests

A September 2004, San Francisco Chronicle article considered the "beauty" of testing. It told the story of 59 year-old veteran Jim Malone, who'd been told in 1996 that he was HIV positive. His health was diagnosed as "very poor." He was classified as "permanently disabled and unable to work or participate in any stressful situation whatsoever."

In 2004, his doctor sent him a note to tell him he was actually negative. He had tested positive at one hospital, and negative at another.

Nobody asked why the second test was more accurate than the first (this was the protocol at the Veteran's Hospital). Having been falsely diagnosed and spending nearly a decade waiting, expecting to die, Malone said, "I would tell people to get not just one HIV test, but multiple tests. I would say test, test and retest."

In the article, AIDS experts assured the public that the story was "extraordinarily rare." But the medical literature differs significantly.

The Numbers

In 1985, at the beginning of HIV testing, it was known that "68% to 89% of all repeatedly reactive ELISA (HIV antibody) tests [were] likely to represent false positive results." (New England Journal of Medicine. 1985).

In 1992, the Lancet reported ("HIV Screening in Russia") that for 66 true positives, there were 30,000 false positives. And in pregnant women, "there were 8,000 false positives for 6 confirmations."

In September 2000, the Archives of Family Medicine stated that the more women we test, the greater "the proportion of false-positive and ambiguous (indeterminate) test results."

The tests described above are standard HIV tests, the kind promoted in the ads. Their technical name is ELISA or EIA (Enzyme-linked Immuno-sorbant Assay). They are antibody tests. The tests contain proteins that react with antibodies in your blood.

False Positives

In the U.S., you're tested with an ELISA first. If your blood reacts, you'll be tested again, with another ELISA. Why is the second more accurate than the first? That's just the protocol. If you have a reaction on the second ELISA, you'll be confirmed with a third antibody test, called the Western Blot. But that's here in America. In some countries, one
ELISA is all you get.

It is precisely because HIV tests are antibody tests that they produce so many false-positive results. All antibodies tend to cross-react. We produce anti-bodies all the time, in response to stress, malnutrition, illness, drug use, vaccination, foods we eat, a cut, a cold, even pregnancy. These antibodies are known to make HIV tests come up as positive.

The medical literature lists dozens of reasons for positive HIV test results: "transfusions, transplantation, or pregnancy, autoimmune disorders, malignancies, alcoholic liver disease, or for reasons that are unclear..." (Archives of Family Medicine. Sept/Oct. 2000).

"[L]iver diseases, parenteral substance abuse, hemodialysis, or vaccinations for hepatitis B, rabies, or influenza..." (Archives of Internal Medicine, August 2000).

The same is true for the confirmatory test the Western Blot. Causes of indeterminate Western Blots include: "lymphoma, multiple sclerosis, injection drug use, liver disease, or autoimmune disorders. Also, there appear to be healthy individuals with antibodies that cross-react...."
(ibid).

Pregnancy is consistently listed as a cause of positive test results, even by the test manufacturers." [False positives can be caused by] prior pregnancy, blood transfusions...and other potential nonspecific reactions." (Vironostika HIV Test, 2003).

Inflated Africa Numbers

This is significant in Africa, because HIV estimates for African nations are drawn almost exclusively from testing done on groups of pregnant women.

In Zimbabwe last year, the rate of HIV infection among young women decreased remarkably, from 32.5 to 6 percent. A drop of 81 percent overnight. UNICEF's Swaziland representative, Dr. Alan Brody, told the press that, "The problem is that all the sero-surveillance data came from pregnant women, and estimates for other demographics was based on that."
(PLUS News, August, 2004).

Flawed Samples

When these pregnant young women are tested, they're often tested for other illnesses, like syphilis, at the same time. There's no concern for cross-reactivity or false-positives in this group, and no repeat testing. One ELISA on one girl, and 32.5 percent of the population is suddenly HIV positive.

The June 20, 2004 Boston Globe reported "the current estimate of 40 million people living with the AIDS virus worldwide is inflated by 25 percent to 50 percent." It said that HIV estimates for entire countries have, for over a decade, been taken from "blood samples from pregnant women at prenatal clinics."

But numbers about "AIDS deaths, AIDS orphans, numbers of people needing antiretroviral treatment, and the average life expectancy" are all taken from that one test.

I've certainly never seen this in a VH1 ad.

At present there are about six-dozen reasons given in the literature why the tests come up positive. In fact, the medical literature states that there is simply no way of knowing if any HIV test is truly positive or negative:

"[F]alse-positive reactions have been observed with every single HIV-1 protein, recombinant or authentic." (Clinical Chemistry. 37; 1991). "Thus, it may be impossible to relate an antibody response specifically to HIV-1 infection." (Medicine International. 1988).

Ambiguous Results

And even if you believe the reaction is not a false positive, "the test does not indicate whether the person currently harbors the virus."
(Science. November, 1999).

The test manufacturers state that after the antibody reaction occurs, the tests have to be "interpreted." There is no strict or clear
definition of HIV positive or negative. There's just the antibody reaction. The reaction is colored by an enzyme, and read by a machine called a spectro-photometer.

The machine grades the reactions according to their strength (but not specificity), above and below a cut-off. If you test above the cut-off, you're positive; if you test below it, you're negative. So what determines the all-important cut-off? From The CDC's instructional material: "Establishing the cutoff value to define a positive test result from a negative one is somewhat arbitrary." (CDC, 2003)