Is Aids a Myth

Cyrus

Hi Tara,

I see where you are going with this, but since I am not a Biology major, please do.

Also,

What do you say in response to his claim of lots of false positive testing used by clinical researchers in populations that are highly prone to giving false testing results, or the fact that testing positive for AIDs varies from country to country?

But given that these people live in poverty and may suffer from other conditions, isnt it imperative that testing be done to isolate what exactly is the cause of death or illness?

Ivan Seeking

I've heard it argued that African nations often inflate the number of AIDS related deaths because in some sense funding is determined by the death rate.

TaraS

Sure. Many AIDS deniers, for example, use the aforementioned Christine Maggiore's life story as a case in point. She's tested HIV+, but as her organization notes, remains "alive and well." Therefore, HIV doesn't cause AIDS, because she's never developed AIDS.

Of course, if they took a broader picture of infectious disease epidemiology, they'd see how silly this is. With every pathogen known to man (with the possible exception of rabies), we know people who are infected but never develop disease symptoms. Look at tuberculosis, for example--approximately a third of the world is infected with this bacterium. However, only a small fraction of that go on to develop disease symptoms, and only a fraction of those die in any given year. To AIDS deniers, then, because many people carrying TB remain "alive and well," Mycobacterium tuberculosistherefore doesn't cause TB, right? Obviously that's incorrect, but that's one of their big arguments against the current "dogma" that HIV causes AIDS.

However, even medical science doesn't say that all people who are HIV+ will develop AIDS. We know of groups of people who have been HIV+ for years, yet are apparently just fine (even without antiretroviral drugs). These are known as "long-term nonprogressors," and are a group that's actively being studied to see just how they're holding the virus in check--what is it about them that keeps them OK, whereas other people succumb in just a few years if they're not treated? Again, where AIDS deniers sees a group like this and goes, "aha!! These people aren't dying of AIDS, therefore HIV doesn't cause AIDS!", infectious disease epidemiologists, virologists, and immunologists see this as an expected outcome that we see with every other pathogen, and an opportunity to better understand the host/virus interaction.

Similarly, there are people who are repeatedly exposed to the virus, but never seroconvert. Why not? Deniers again cry foul with regard to HIV causation of AIDS, but meanwhile scientists have found factors (such as a mutation in the CCR5 gene, a protein on cells that helps the virus bind and invade host cells) that make a host resistant to infection in the first place. Again, these are things we'd expect with a broader understanding of infectious disease epidemiology, but deniers (wrongly) think it presents a challenge for the HIV/AIDS paradigm.

Again, this is something we see with all diagnostic tests (for any illness, be it cancer, infectious disease, autoimmune disease, etc. etc.)--no test is perfect. All have a rate of false positives or negatives associated with them. With HIV, that's why we use an original screening test, followed by a secondary (more specific) test. The first one will weed out most of the people who are negative (and do so fairly cheaply); the second (more expensive) test will confirm those who are positive.

Deniers like to say that there are all these conditions that will result in false positives. And indeed, a number have been reported in the literature--but do they mention that these reports are typically associated with *one case*? So while they say things like "there are 60 different conditions that have resulted in false positive results," that means that there have simply been ~60 (or heck, I'll be generous and even give them a few hundred) people, with certain conditions, whose condition has been associated with a false positive HIV test (and again, I'll note they are *associated* with this result--not necessarily *causal*). It's a big red herring, because again, we see this with pretty much every diagnostic test. But the HIV test is given to tens of millions of people, and the error rate is very small overall (for the ELISA, on the order of .2% give a false positive; for the Western confirmatory test, false positives occur more like .00001% of the time, with false negatives a bit more commonly at .001% of the time). This is a damn good test, and can additionally be followed up with RT-PCR to determine viral load (even more specific than the protein tests).

As far as differences between countries, I've tried to dig into that, but it's tough to find information out there on that which doesn't come from denialist websites. Different countries may use different confirmatory tests as well, so it's true that there's no universal, worldwide standard as far as HIV diagnosis. In the past, one commenter on my blog has posted standards around the world, and they're not nearly as different as HIV deniers would have you believe. Unfortunately it's tough to search comments and I'm apparently not using the right keyword to find that information right now.

In an ideal world, absolutely. However, the one thing I agree with the deniers on is that these countries are resource-poor, and there's simply not the funds available to do that for every person. Additionally, in some areas, there are cultural traditions that mean that doing autopsies or any kind of post-mortem work violates their beliefs. It's a tough area to work in, and this is why seroprevalence studies of living individuals are carried out instead--to get a snapshot of viral prevalence and disease in a particular area. It's not perfect, but coupled with some trust in the area physicians (as I mentioned previously) and their familiarity with the disease, it's probably as good as we're going to get for right now. (And in this context, keep in mind the thousands of people here in the US, with all our resources, that also die of undiagnosed causes...)

G01

To me the whole agrument of "not ever seeing an HIV virus, just the RNA,etc." is rubbish, considering the paper Moonbear cited.

I'm very skeptical about these videos for this reason and because I'm pretty sure in the first one, one lady call Africa a "country".

LightbulbSun

This is rubbish. Now lets deny air because WE CAN'T SEE IT!

Cyrus

You can see air everyday, its called atmospheric perspective.

Pakbabydoll

WOW no way...., believe it HIV and AIDS are real..

raolduke

I thought that there are two precursors for HIV? I was lead to believe that african/american are more likely to have 1 of these prerequisites?

Mallignamius

Long-term nonprogressors have been studied for years. Has there been any significant progress?

adrenaline

Their cell-mediated immunity is somehow different. Scientists are studying HIV-specific CD4+ Th1 lymphocyte levels and activity, high levels of which seem to the best factor linked to protection in these long term non progressors . I have a small population of these long term non progressors ( Hiv + individuals who maintain a CD4 count of 600 and above without antivirals for at least five years.) One stayed HIV + without progression for 20 years ! All his freinds who went on antiretrovirals died many years before him! He progressed rather quickly to AIDS towards the end of the twenty years and died of herpes encephalitis. He also had crippling rheumatoid and lupus. Off hand I know of three others in my practice who have maintained non progression along with their autoimmune diseases.... almost as if their dysfunctional immune system that causes their body to attack their own organs ( lupus, rheumatid, ankylosing spondylitis, crohns disease etc.) simultaneously keeps their Aids virus in check! Interestingly, there is some data that genetic status such as HLA-B 27 individuals protect from AIDS rapid progression. (These HLA-B27 patients are also more prone to developing such autoimmune diseases that I have mentioned.)

I think right these non progressors are providing a wealth of information for those researchers working on vaccine development.

Anyway, back to the folks discrediting the Aids virus. What did they think was happening to these people's immune system that was making them die from things that just don't kill people with normal immunities, even under the most distressing physical conditions ( ie: starvation)? ( I'm talking about cryptococcal meningitis, toxoplasmosis, PCP pneumonia, etc.) Infections that were almost non existant until the AIDS epidemic. Of course they could try to argue about how these folks died from "normal infections" like cholera, streptococcal pneumonia, malaria etc which also kill non HIV infected folks, but how do they explain these opportunistic infections? MAC colitis ( Mycobacterium avium complex) diarrhea is almost unheard of in those with normal immune systems, and ok, maybe you can argue about chemotherapy induced immune dysfunction ( which predisposes these patients to some similiar opportunistic infections found only in HIV) but I doubt that that many Africans are getting chemotherapy!

I can't do better than Tara on this but let me throw in my measly input. First of all, out of the thousands of medical diagnostic tests out there to diagnose any medical problem, the Aids test ( Elisa followed by western blot which amplifies HIV DNA) is the most sensitive and specific test out there. Tara was right, it's a damn good test in fact,we were taught in medical school that many other diagnostic testing out there don't come close to surpassing the AIDS test in its accuracy! The serum tests that look for Lupus or rheumatoid arthritis or syphllis doesn't even come close to the accuracy of the AIDS test. Why no "conspiracy" about rheumatoid arthritis or lupus or syphillis?

The rapid ELISA test has a sensitvity and specificity of over 99%. (The sensitivities and specificities close to 100% really make the test very reliable in the right clinical setting.) I don't know of any other medical diagnostic serum testing that is so sensitive or specific. . And yes there are false postives and negatives. However, if you look at the fact that the most common malaria test has only a sensitivity of 88% and specificity of 95 %, the malaria testing has a much higher rate of false positives! Hot dang, there must also be a conspiracy about the malaria epidemic!

Mallignamius

Thank you for the update.

For curiosity, what vectors are being considered for inducing cell-mediated immunity to HIV1? And have any vaccine candidates passed phase II yet?

adrenaline

You better let a biologist answer the first half. as for phase III trial one was done in 1993 that was not too promising ( efficacy of 20% and the vaccine consisted of 7 shots, ouch!) here are the details

http://www.medscape.com/viewarticle/452480

I haven't really heard of any new ones down the pipe. I'll ask my ID folks here and post later.

Curious3141

The ELISA detects antibodies to HIV +/- p24 Antigen (in the case of 4th generation assays). It is a highly sensitive and highly specific assay, but is capable of giving significant numbers of false positives in a low prevalence population (where the pre-test odds are low). This is a common pitfall : low prevalence compromises positive predictive value in any test with less than 100% specificity.

The Western Blot (or immunoblot) detects specific antibodies to weight sorted HIV-1 proteins belonging to the 3 classes (gag, pol, env). It is a less sensitive but more specific assay than the ELISA, and is often used for confirmation and disease follow-up. The Western Blot pattern can be positive, negative or indeterminate and there are different criteria for reading them (CDC/ASTPHLD, American Red Cross, CRSS etc.) The pattern can evolve with disease progression. HIV-2 specific WBs are available.

Nucleic acid tests are the most sensitive, most specific and most expensive. They are difficult to perform with expertise (if done improperly, false negatives due to sample matrix inhibition and false positives due to sample-sample carryover contamination abound). They are uncommonly used in routine clinical diagnosis and are generally reserved for screening blood products prior to human transfusion. They are also sometimes useful in testing neonates with vertically acquired maternal antibodies to HIV. You can test for viral RNA or proviral DNA (which is the form that integrates into human cells). You can use different assay methodologies (PCR for DNA, RT-PCR for RNA and bDNA (branched chain DNA assay)).

adrenaline

very true which is why no medical test should be ordered unless the pretest probability for the disease is high and the local prevalence of the disease is taken into consideration. Ordering a HIV test in a virginal nun is probably not a good idea. ( ELisa with reflex western blot if positive). For that reason I don't order CA 125s at all for ovarian cancer screening, the sensitivey and specificity suck. However, compared to any singular medical diagnostic test I have yet to find any medical diagnostic test ( both serological as well as say, radiographic ( ex helical cat scan for pumonary embolism where senstiviites and specificities range from 57-95% and 78%-98% respectively depending on the study and type of cat scan) that comes close to the HIV test! There is no doubt under the right circumstance it can produce false positives and negatives but there is no other medical diagnostic test that I can recall offhand that has such a good specifcity and sensitvity ( Thus the potential to diagnose a blood clot in the lungs is fraught with much more false negatives and positives.) (I was sleep deprived yesterday so I meant to say DNA isolation vs amplification). Thats why this guy bringing up the rate of false positives and false negatives as the main thrust of his argument is way off base. He has no idea that almost all other medical diagnostic testing are far less sensitive and specific!

Curious3141

The Western blot is an immunologic (antibody) test. It is not a nucleic acid (DNA/RNA) assay at all.

I agree with the rest of the stuff about sens/spec. etc.

adrenaline

you are right, i keep thinking of pcr and my lack of sleep is making me3 punchy.