The AIDS Physician and the Actuary (Part I)
- Alex
The Perth Group does not claim originality for the invention of heuristic discourses. That belongs to Socrates and scientists such as Giordano Bruno and Galileo.
Doctor: I am sorry to have to tell you but your antibody test has come back positive.
Patient: You’re telling me I have HIV?
Dr: I’m afraid so.
P: Couldn’t the test be mistaken?
Dr: Unfortunately not. The tests we use are extremely sensitive and specific. I have never known them to make a mistake.
P: Doctor can you please explain how this particular test can be so accurate? And how it actually works?
Dr: Certainly. In simple terms the test has detected some antibodies to HIV in your blood. The only way you can get those antibodies is to come into contact with HIV.
P: When you say the antibodies are ‘to’ HIV, what do you mean?
Dr: I mean they are directed against HIV. When your body came into contact with HIV it registered the HIV proteins as something foreign. As a result your immune system was switched on to produce a set of antibodies which specifically combine with these proteins.
P: How do you know these antibodies are actually there? In my body?
Dr : Because when we mix your blood with the proteins in the antibody test kits there's a reaction.
P: How do you know there's a reaction?
Dr: Because when we add your serum to a solution containing the test kit proteins the solution changes colour. We can see that and we can even measure the amount of reaction by the amount of colour change. We get out a number which makes it quite objective.
P: And when you say ‘reaction’ do you mean a chemical reaction?
P: Yes. There is a chemical reaction. That's because the antibodies in your blood recognise the HIV proteins. The shape of the antibodies and protein molecules are complementary. They fit together perfectly. Like a lock and key. That’s what specific means.
P: But this is not a test for the actual virus is it? The virus particles? You haven’t found those in my body?
Dr: No it’s not the actual virus. It’s an indirect test. As I explained, it’s a test that looks for antibodies that are manufactured in response to the presence of the virus proteins. That’s why we call them HIV antibodies. But the virus is there all right. There’s no other reason why your body would produce such antibodies.
P: So if you looked you could also find the virus particles?
Dr: Maybe and maybe not. Not necessarily in your blood. That would be very hard to do because to see them you need millions and millions of particles. In fact no one has ever managed to find HIV particles in a patient’s blood. But we could use your blood to culture the virus. Outside your body. Or we could do the same thing from a small piece of lymph node for example. But these kind of tests are technically demanding. And expensive. And quite unnecessary.
P: Where do you get the HIV proteins from?
Dr: From HIV. They form the major part of the HIV particle.
P: I presume these proteins don’t occur anywhere else then?
Dr: No. They belong to HIV.
P: And nothing else you know of could induce my immune system to make these antibodies?
Dr: The way the tests have been refined and interpreted, no.
P: So you’re sure my body has this virus in it?
Dr: As sure as anyone can be.
A week later.
Patient: Doctor I’ve done a literature search and I’ve looked up some articles in the University library. I’ve made you some copies as well.
Dr: I assume you have a few more questions then? About what we discussed last time? I know it's hard coming to grips with something like this.
P: To be perfectly honest I’m confused. I’d really like to know what you think. For instance, last week you told me the HIV proteins, the ones used to test my blood for antibodies, don’t occur anywhere else except in HIV.
Dr : That’s right.
P: Here’s a paper I found. It’s called “HIV proteins in normal human placentae.1 It’s written by a group of scientists who tested tissue from the placentas of several healthy, pregnant women using antibodies directed against four of the HIV proteins. They found three HIV proteins in women who are not infected with HIV. They were p18, p24 and p120. And here’s another article. This one’s called “Monoclonal antibodies to the human immunodeficiency virus p18 protein cross-react with normal human tissues”.2 In this paper the HIV p18 protein was found in the thymus and tonsils and brains of people who are not infected with HIV. Are you familiar with these papers?
Dr: I’m sorry I’ve not seen these before. And I would have to read them before passing comment.
P: You might have to read quite a few. Here’s another paper where blood from five patients who were HIV negative was cultured and again the p24 protein was found. I’ve got another paper for p32. And several other papers confirming what I’ve already said about the others.1-7 8 9-16 I’m no expert but it seems to me if the antibodies used in these experiments are the same antibodies that are in AIDS patients, or in me for instance, and they specifically recognise the HIV proteins, they should not register anything in HIV negative people’s blood or tissues. Doctor what is going on?
Dr: You’re jumping to the wrong conclusion. The HIV proteins are not there. It only looks that way. As your second paper says in its title, the antibodies cross-react with some normal human proteins. That occur in brain for example.
P: But aren’t the antibodies they used in these experiments meant to be specific? Don’t they recognise HIV and nothing else but HIV?
Dr: When I explained the test to you last week I did say I was giving you a simplified version.
P: All right but how come these antibodies react in normal people? If there's not a simple answer is there a complicated answer?
Dr: What these papers are describing is not strange or mysterious. And it’s not a secret. The problem is that antibodies aren’t always exactly 100% specific. Sometimes they can and will react with other things besides what they’re meant for. That’s what cross-react means.
P: So you’re saying that HIV antibodies can react with things other than HIV?
Dr: Yes.
P: So if an antibody reacts with something that’s not proof it’s directed against that something?
Dr: It may not be.
P: Are HIV antibodies the only antibodies that can cross-react?
Dr: No. In theory it’s possible for any antibody to cross-react. It’s not a property confined to one type of antibody.
P: Well if HIV antibodies can cross-react with proteins which are not HIV, like in the brain for example, then why can’t non-HIV antibodies cross-react with the proteins you say do come from HIV?
Dr: In theory they can.
P: What about in practice?
Dr: Yes they can. That is reported in the literature.
P: So how do you know the antibodies in my blood, the ones that react in my test, are caused by HIV and not by something else?
A week later.
Dr: I understand this must be causing you considerable distress. So I’ve set aside some extra time to fully go over these tests.
P: I appreciate that doctor. We were talking about cross-reactions.
Dr: I remember. OK. And let me know if I lose you in what I am about to say. Sometimes antibodies to one protein do react with another, different protein. That happens because the fit between the bit of the protein the antibody reacts with, and the antibody itself, although not 100% perfect, is still good enough for a reaction to take place.
P: I understand.
Dr: Now back in 1985, when the HIV tests were being designed, when HIV testing was in its infancy, it was discovered there are people who are not infected with HIV who have antibodies that react with one or even a couple of the HIV proteins.
P: But that wasn’t an infection?
Dr: No, that was cross-reactions.
P: How many people does that affect doctor?
Dr It varies depending on what papers you read. But in one of the types of test we do, it's called the Western blot, can be as high as 25%. It’s certainly at least 15%. The 25% figure is from Australia. From studies of healthy blood donors.
P: 25% of people can have a positive Western blot?
Dr: No. 25% of people can have antibodies that react with one or perhaps two of the ten HIV proteins that are in the Western blot strips.
P: But one or two is not enough to make you positive on the Western blot?
Dr: Correct.
P: How do you know one or two antibodies doesn’t mean infection with HIV? That’s how it used to be. Montagnier said an antibody to the p24 protein was enough. Gallo said an antibody to p41 was sufficient. How do you know one or two antibodies reacting in the Western blot aren’t real HIV antibodies?
Dr: Because these people don’t belong to a risk group. And they’re healthy and they stay healthy. They don’t go on to develop AIDS. And when they donate blood the recipients don’t develop AIDS either.
P: And 25% of the population couldn’t possibly be infected with HIV?
Dr: Exactly. If they were I can’t imagine how many hospitals we would need to treat them all.
P: And for HIV to get that common life would have to be one continuous orgy?
Dr: A very good point.
P: But these antibodies must have come from somewhere?
Dr: That’s true. Something must be responsible. And it’s often hard to know exactly what. Although it really isn't important to know that. Perhaps they’re caused by some other illness or some exposure to something in the environment. But whatever it is, it’s not HIV.
P: I understand.
Dr: Now, I said before, we do have a way to sort out true HIV antibodies from all the others.
P: Yes I remember your saying that. The wheat from the chaff.
Dr: That’s a good analogy. Let me tell you what happens. When we first test you we do what’s called an ELISA test. That is known as a screening test. In the ELISA we test your blood against all the proteins from HIV. All mixed up together. That’s about ten proteins by the way. So we have all the proteins in one test-tube and then we add a few drops of your blood sample. Minus the red blood cells of course. Otherwise we wouldn’t see any colour except red. So we add the serum, where the antibodies are dissolved, not the whole blood. If there’s a reaction the solution changes colour. We can see that. As I said before, we measure the amount of the reaction by measuring the passage of a light beam through the solution.
P: With the spectrophotometer?
Dr: Yes. You’ve obviously been doing a lot of study.
P: I also did two years of chemistry as an undergraduate.
Dr: OK. But there’s a problem with the ELISA. It’s not that specific. Or at least it’s not specific enough. We can’t do just one ELISA test then look you in the eye and say you’re infected. That would not be considered best practice.
P: So why do you use this test?
Dr: Because it is the most sensitive antibody test. By that I mean it’s guaranteed to pick up every HIV single antibody anyone could ever have—but at a price. It also has a tendency to pick up non-HIV antibodies as well. To use your analogy, it picks up all the wheat OK, every single grain, but along with that some of the chaff. By that I mean antibodies which are not HIV.
P: I still don’t understand why you use it.
Dr : We use it to screen people. The way it works is this: If the ELISA is negative it hasn’t picked up any antibodies. HIV or non-HIV. So the person is not infected. In that case that’s as far as we need to go. So it’s a very useful first up test. It’s used a lot for donating blood. Most people who want to donate blood are negative on the ELISA. In fact most people period are ELISA negative. End of story.
P: And what if a blood donor is positive?
Dr: Then we have to dig deeper. But for the blood bank it means they know straight away they can or can’t use that person’s blood. It’s quick and easy.
P: But what happens to the blood donor who is positive on the ELISA?
Dr: If the blood bank find a positive they hand over the case to an approved laboratory for running further tests. Such as our laboratory. In fact that’s the law in this country. Not just any person or laboratory is allowed to do the further tests. Then it’s really no different from what happened in your case. We dig deeper by doing another test. A test which is different from the ELISA. In most parts of the world the second type of test is the Western blot. The difference is that in the Western blot the ten HIV proteins are not mixed up together. They have been separated from each another along a paper strip about half a centimetre wide. That way we can identify precisely which HIV proteins are reacting. Or if you like, we can tell which antibodies you have to which HIV proteins.
P: How do you read the Western blot?
Dr: By eye. Every place where an antibody reacts with one of the HIV proteins the strip changes colour. So you end up with a series of coloured dots along the strip. We call those bands. The lab technician looks at the strip and reports the names of the bands that light up. Each band is named with a ‘p’ for protein and then a number which is its molecular weight in thousands. I think you’ve already found that out.
P: How does the number of bands determine whether someone is infected or not?
Dr: Well you might have one band or you might have ten bands. If you only have a couple of bands then you’re almost certainly dealing with cross-reactions. But if you have four or more your test is positive and you are infected. Or of course you might have no bands which means you are definitely negative and not infected.
P: So the Western blot is used to work out whether the ELISA is right or wrong?
Dr : Yes. We say the Western blot is a ‘confirmatory’ test.
P: And knowing which bands a person has distinguishes real antibodies from cross-reactions?
Dr: Yes. We know that HIV antibodies cause particular patterns of bands to show up. Kind of like a Lotto ticket. Certain combinations invariably mean a prize and others don’t.
P: What does my Western blot test show? Which antibody bands do I have?
Dr: You have antibodies to p41, p24, p32 and p18. That’s four bands and it’s also one of the several possible band patterns that makes a positive test.
P: I still don’t understand how you can know that some band patterns are caused by HIV and others are not.
Dr: OK. Tell me what you don’t understand.
P: Last week I asked how you know blood donors who have one or two antibodies aren’t infected with HIV. You told me it’s because they aren’t sick or in a risk group.
Dr: And they don’t go on to develop AIDS.
P: OK. But if I had only one band on the Western blot you’d say that was not an HIV antibody?
Dr : You can have up to three bands not caused by HIV antibodies. Or at least the chances are very slim. Of course it might also be that you haven’t produced all your antibodies yet. It’s early days. You are on the way but your infection was only a few weeks ago. In some people it can take a couple of months for all their antibodies to show up. The bands don’t appear simultaneously. It’s called the window period.
P: I could have as many as three antibodies and not be infected?
Dr: Yes. As many as that. And as long as you don’t get any more.
P: So I could have three bands and not have HIV while the next patient you see today could have the same three plus one extra band. And that extra one produces a pattern you say is caused by ‘real’ HIV antibodies.
Dr: That’s quite possible.
P: Then the three bands he shares with me must be real HIV for him but not for me. So that extra band makes all the difference?
Dr: Precisely.
P: I don’t get it. Why should just one extra band be ‘real’ when the others on their own aren’t? How can a number or combination determine which antibodies are real and which aren’t? I mean if you have three pieces of fruit that aren’t apples and then you add a fourth that is an apple, does that make four apples?
Dr: I agree but we have evidence. I said it before. We know which band patterns are caused by HIV because we’ve analysed which groupings of bands distinguish people with AIDS from those who remain healthy. It’s really not that difficult.
A week later
P: I’ve been thinking about what you told me. I’m sorry but I still have problems.
Dr : Well we better keep talking. Fire away.
P: I have a cousin in the US who works for a biotechnology company. He sells antibody test kits to several New York hospitals. He faxed me a packet insert for the ELISA and Western blot. One of each. Which I read last week.
Dr : And what did they say?
P: They confirmed what you said. With the ELISA you can distinguish most people with AIDS from healthy people. If you use a combination as you said, an ELISA followed by a Western blot, the distinction is almost perfect.
Dr: Then doesn’t that put the matter to rest?
P: Maybe. Maybe not.
Dr What’s the difficulty?
P: The biotechnology companies want their tests to be highly specific. In other words, they don’t want their tests to react in someone who’s not infected with HIV. And neither I guess do the doctors. And certainly not the patients. So, as you said, they try their tests out on healthy blood donors. To see how good they are. They assume, quite rightly I suppose, those sorts of people don’t have much chance of getting AIDS or being infected with HIV.
Dr : That’s right. They’re extremely unlikely to be infected with HIV. That’s been proven time and time again by millions of tests at the blood banks.
P: Yes doctor but when the biotechnology companies test their tests on blood donors they go further. They actually define the blood donors as not infected. The World Health Organisation does the same thing.
Dr: That’s correct.
P: Well that’s one of the problems. When I read about healthy blood donors, not being in a risk group and all the rest, I asked myself, who are these people? Where do they live? What kind of people are they? What are their habits? Where do they hang out? And you know who it reminded me of?
Dr: No.
P: It reminded me of me. I’m healthy. My friends regularly tell me how well I look. I only got HIV tested because I need life insurance. I’m not gay, I’m not a haemophiliac, I’m never been a drug taker. I’ve not been promiscuous. I haven’t been an angel but since getting married my only sexual partner has been my wife. And because we were about to start a family, a couple of months ago, unbeknown to me, my wife had an HIV test. And she’s negative.
Dr: What point are you making?
P: Doctor I could easily be in a group of people the manufacturers of antibody tests use to determine how accurate their tests are. And when they tested me I’d be positive all right but they would have already defined me as non-infected. To me that’s a false-positive. Don’t you agree?
Dr : To be perfectly frank I think you are somewhat in denial over this. Believe me I'm not having a go at you but that’s what people often do when the news is not good. You realise there are other tests we could do to settle this matter?
P: You mean the viral load test?
Dr Yes.
P: But according to my packet inserts, when biotechnology companies and the WHO investigate their tests, they don’t do that. They don’t go checking the antibody positive people with viral load tests. So why do it to me?
Dr: To reassure you?
P: There’s a man I talked to this morning in the waiting room. He told me he’s had a positive antibody test since 1987. He didn’t have his first viral load test until 1992. In fact I know there were no such things as viral load tests in 1987. And this man didn't have a viral load test to prove his antibody test is correct. It was to do with his drug treatment. If that man didn’t need a viral load test to diagnose him in 1987, why do I in 2004?
Dr : Because most of the people who come to this clinic have clearcut reasons for being infected. Their cases are straight forward. I’m sure from all your reading you wouldn’t be surprised to know most of our patients are either gay or drug users.
P: But doctor three weeks ago you told me I was infected with HIV. You didn’t say I was a difficult case. You didn’t tell me I would need another test to sort out my antibodies. And if I’d come to you fifteen years ago with a positive test, before there were viral load tests, surely you wouldn’t have told me I wasn’t infected. That’s not what happened to the man in the waiting room. And if it wasn’t for me and the Internet we wouldn’t even be having this conversation. And I understand what you are saying about gay men and drug users. But to me that just makes the problem worse.
Dr : I’m beginning to think you must be reading some very unusual material.
P: All I’ve read is what’s at PubMed. To find the paper on HIV in the normal placenta I just entered “HIV p24 protein”. Up it came. Along with about 3000 others. So it took a bit of work. I assume PubMed is where doctors do their literature searches. And I’m sure you know that PubMed only list journals which are indexed and the vast majority of those are peer reviewed.
Dr: Yes but why do you say the problem is worse in gay men and drug users?
P: Doctor I’m an actuary. I have a PhD in mathematics. From Oxford. I came to Australia six years ago because my wife is a top notch forensic scientist. She was head hunted by your National Crime Commission. My field is statistics. I understand probabilities and the like. That’s what I’m paid to do. If you tell me a few things about yourself I can tell what chance you have of getting any disease you name and living to any age you care to say. If you want to know the chance your wife will outlive you by a certain number of years I can also tell you that.
Dr: I’m not questioning your competence in your field. But you seem bent on questioning me in mine. Please tell me what problems do you see with gay men and drug users.
P: You tell me any antibody molecule can cross-react. It can pick off some protein it’s not destined for. So let’s assume that each individual antibody molecule has some probability of a cross-reaction. I have no idea what it is. Do you?
Dr: No. I don’t think that kind of data is available.
P: OK but if healthy people with a normal number of antibodies have a ¼ probability of reacting with one of the ten HIV proteins the probability can’t be small. If a healthy person has say ten thousand different antibodies, and a target of ten HIV proteins, you have a hundred thousand combinations to try. That’s a lot of locks and keys. If you double the number of antibodies you have two hundred thousand combinations. And that’s just on numbers. I don’t know how variety affects the maths. So the more antibodies you have and the more things you’re exposed to and the more likely you will generate an antibody that can cross-react in these tests. Or in any test for that matter. And that’s the problem. At least the way I see it.
Dr You’ll have to explain.
P: Let’s ask ourselves, what kind of people are likely to have the greatest number and variety of antibody molecules? In general. Surely the people in the AIDS risk groups must head the list? What about all the germs and foreign substances that gay men and drug addicts are exposed to? And haemophiliacs who get infused with foreign proteins that come from thousands of blood donors. And what about Africans? Who have all manner of diseases such as TB and fungal and parasitic infections which also cause antibodies? And the organisms that cause these diseases just happen to be representative of the commonest AIDS defining diseases in Western AIDS patients. Who don’t actually come from Africa. So the groups of people with the greatest probability of having cross-reacting antibodies, antibodies that will confuse these tests, are the very groups in which you say the tests rarely make a mistake. It just doesn’t add up doctor. I’d say it would be a miracle if any of the antibodies in AIDS patients were genuinely HIV.
Dr: I honestly don’t follow your logic. You told me that the laboratory test inserts your cousin sent from America confirmed the antibody tests can separate patients with AIDS from patients who are healthy. Isn’t that right?
P: Yes there we agree. And we agree they do this very accurately.
Dr: Surely then if a positive antibody test distinguishes between AIDS and healthy people then HIV must be involved in one group, the AIDS patients, and not in the other group? The healthy people.
P: Why?
Dr: Because HIV causes AIDS. If the test distinguishes between AIDS and not having AIDS then it automatically distinguishes between having the cause of AIDS and not having the cause of AIDS. Which is HIV. It’s just another way of saying the same thing. It doesn’t matter which way around you say it.
P: No you cannot deduce that doctor.
Dr : Why not? It can’t be any other way. Unless of course you say HIV is not the cause of AIDS. Surely you’re not suggesting that? Not seriously? Have you been reading some of the dissident junk on the Internet?
P: Have you read any of that junk doctor?
Dr: No of course not. Look, this is getting out of hand. There are important things we must discuss and the sooner the better. We seem stuck on what really shouldn’t be a problem at all. I respect your right to ask questions and I’ve tried my best to answer them but obviously I’m not able to satisfy you. Perhaps you would prefer to talk to one of my colleagues?
P: No that will not be necessary doctor. I have every confidence in you. And in this clinic. Another doctor would only increase my confusion. Let’s call it a day. I’ll try and come to come to grips with it next time.
Dr: Very well. We certainly need to move on.
A week later.
P: Doctor I think I’ve worked out a way to explain my misgivings.
Dr: I’m glad to hear it.
P: Let’s talk about tests in general terms. What actuaries do for example. It’s not too different from our last discussion.
Dr: OK.
P: Actuaries are interested in how long people live. Which is another way of saying when people die. So we collect data about large groups of people who have something in common. People who have say heart disease or diabetes. We work out whether having or not having one of these diseases will affect a person’s chances of being or not being alive at some future date. In a statistical sense of course.
Dr: Go on.
P: So what we do is very similar to your antibody tests and AIDS. Your take people with or without a positive antibody test and contrast that with the risk of having or getting AIDS or staying healthy.
Dr: Yes.
P: Now this is where I think the medical profession or the laboratory scientists or whoever decides these things have gone beyond their data. The outcome actuaries seek is whether a person is dead or alive. And one of the ‘tests’ we use, is what diseases they have or don’t have at various times before they die. So our tests are diseases and our outcome is death. Clear and unambiguous. You’re either dead or you’re not.
Dr: Go on.
P: We don’t use a substitute for dead bodies. We don’t count the numbers of death notices in the papers. We don’t tally up how much timber undertakers order. Or how small the forests are becoming. We don’t ask Centre Link how many pensions they’ve cancelled. We go straight to the real thing.
Dr OK.
P: When it comes to the antibody tests the medical profession doesn’t deal with the real thing.
Dr: I don’t follow.
P: You told me the antibody tests diagnose HIV infection.
Dr: That’s right.
P: But you haven’t produced any evidence for that. What you’ve described is a test for AIDS. Or, more accurately, of diseases which the medical profession defines as AIDS. None of these diseases are new. They’re just been bundled together because in the early 1980s gay men in large Western cities started to get them more frequently than ever before. Isn’t that right?
Dr: Yes, that is right.
P: So it’s AIDS that measure the antibodies against. The biotechnology companies and the WHO say it too. You say it’s a test for HIV but you measure it against AIDS.
Dr: I already explained that…
P: I know. You say you can use AIDS as a substitute for HIV. And not having AIDS as a substitute for not having HIV. Well I don’t think you can do that.
Dr: Why not?
P: Several reasons. First: AIDS is not HIV. They’re totally different. AIDS is 30 diseases. HIV is allegedly a virus. Second: The AIDS diseases have been around for hundreds, maybe thousands of years. Long before we had AIDS. There’s an account of Kaposis’ sarcoma in the Ebers papyrus. From ancient Egypt. Dating from 2500 BC. So if HIV is really a virus and does cause the AIDS diseases it’s not the only cause. It’s not unique. How about tuberculosis? TB has been found in Egyptian mummies. Would you use an Egyptian mummy as a substitute for HIV?
Dr This is beginning to sound ridiculous…
P: You can use AIDS as an HIV substitute if and only if the sole cause of these 30 diseases is HIV. Which it isn’t. There’s no way around that. If you want to say AIDS can be substituted for HIV then actuaries can substitute death for the number of cancelled pensions.
Dr Hold on…
P: The other faulty piece of logic is to use an antibody test as part of the AIDS diagnosis. If a positive antibody test is part and parcel of having AIDS it stands to reason there will be a perfect correlation between these antibodies, wherever they come from whatever they are, and AIDS. But that would be a man made correlation.
Dr: Look we may diagnose AIDS with an antibody test now but that was not what we did when the HIV tests were developed. They were verified against AIDS. A clinical diagnosis of AIDS. By that I mean history and examination. Plus a few test like X-rays. But not antibody tests. But when we did an antibody test, as an experiment if you like, that’s when we discovered all AIDS patients have these antibodies. And if you don’t have these antibodies you don’t have AIDS. And that has been found time after time. That’s why an antibody test is now part of the diagnosis.
P: Doctor that doesn’t prove the antibodies are caused by HIV. It just proves that AIDS patients have some antibodies which react with these proteins in the test kits. Which you say could be cross-reacting and therefore not HIV. So what you have is a blood test for AIDS. Or a blood test that predicts an increased likelihood you will get sick from certain diseases. That’s fine if that’s what you want. But that’s not the same thing as proving the antibodies are caused by a virus.
Dr:???
P: There’s more doctor. Third: A couple of weeks ago I suggested I was a false positive. You didn’t agree. That means you want to have things both ways. If you’re a biotechnology company you want to use people like me as stand ins for being HIV free. You can read it in their inserts. The one I have says ‘Random donors are assumed to have a zero prevalence of HIV antibody”. So that’s the rule. Once you set up the rules you can’t break them. Which means anyone in this group who’s positive must be recorded as a false positive. But the same person sitting in your clinic the next day is truly infected. That could easily apply to me.
Dr: I really think all your reading has made you quite confused.
P: What I understand doctor is this: If biotechnology companies and the World Health Organisation are quite happy to use people without AIDS including healthy people as HIV-free substitutes to verify their tests then there can be no epidemic of HIV.
Dr: How on Earth do you come to that conclusion?
P: Because most people on Earth with a positive antibody test don’t have AIDS and in fact most are healthy.
Dr: You’re telling me all those people, millions of them, 30% of some African countries, aren’t infected with HIV? They’re all false positives?
P: It’s not me saying that doctor. I’m only drawing a conclusion based on the rules you and the WHO recommend and approve. I don’t make up the rules. I’m just saying you should stick to them.
Dr: Is there anything else?
P: Have you ever read a packet insert?
Dr : No. I don’t do the tests. They’re done by the laboratory staff.
P: Do they read the packet inserts?
Dr: I don’t know.
P: Don’t the agencies that approve the tests read them?
Dr: I don’t know that either.
P: Can I read you something else from my packet insert?
Dr: Sure.
P: Both my packet inserts say “At present, there is no recognized standard for establishing the presence or absence of antibodies to HIV in human blood”. What’s your opinion on that statement doctor?
Dr: I’d like to hear your opinion.
P: OK. My opinion is that biotechnology companies employ a lot clever people. And if a biotechnology company was developing a pregnancy test someone in the organisation would know the recognised standard for pregnancy is whether or not a woman has a baby. So it’s not rocket science to know that the recognised standard for a test to diagnose HIV is whether or not the person has HIV. If that’s what the test is for that’s what it should judged against. Which means the biotechnology companies know these tests are not being judged against HIV itself. Otherwise their lawyers wouldn’t be telling them to put that sentence into the test kit packet inserts.
Dr: So you do not accept what I explained before?
P: Doctor I’m commenting on a packet insert. I’m offering my opinion that the biotechnology companies must know HIV is the gold standard method for validating the antibody tests but that it’s not being used. Why this is so I don’t know. And why test manufacturers repeatedly warn whoever reads their packet inserts about this I don’t know either. But I’m going to try and find out.
Dr: So what would actuaries have us do?
P: I can only speak for this actuary doctor. You’ve already told me that cross-reacting antibodies can react in the HIV test. You said that in the Western blot one or two antibodies are most likely caused by cross-reactions and not HIV. When I asked how you know that you said it’s because of the band patterns the antibodies form. I don’t see how patterns or numbers distinguish between real and cross-reacting antibodies. I don’t believe you can know what something is just because there’s more of it. That’s why I said maybe all antibodies in these tests are cross-reacting and not HIV. Or maybe they really are all HIV. Well there’s an easy way to find out.
Dr: And what’s that?
P: Use the virus. Do an experiment comparing the antibodies against the virus itself. After all, that’s what the test is for. It’s a test for HIV. It’s not a test for AIDS.
Dr: And how would you do that?
P: Take say a thousand people. Some with AIDS, some with other diseases like AIDS, some with diseases which are not AIDS and some healthy people. You can’t restrict your choice of non-AIDS people to those who are healthy. If you do you’ll be avoiding the problem of cross-reacting antibodies. The non-AIDS group must include sick people because these are the people who are likely to have generated increased amounts of different antibodies that might confound the test. If you only use healthy people you don’t expose the test to enough cross-reacting antibodies. Then you compare having or not having a positive antibody test with having or not having HIV. As proven by virus isolation. But, as the test manufacturers tell us in a round about way, this has not been done. And it should have been done long before the tests were used on the general population.
Dr: Well what are you going to do about your tests?
P: For the next three months I’m going to try and forget I have a positive test. Actually I’m encouraged by something else I read in the packet insert. “The risk of an asymptomatic person with a repeatedly reactive serum sample developing AIDS or an AIDS-related condition is not known”. So it seems no one is very sure what a positive test means outside a risk group. Meantime I’ll go to my GP to make sure I haven’t got TB or something else that might set these tests off. I got immunised for ‘flu and tetanus about three months ago. Maybe that’s the reason. I know I could be wrong so my wife and I will put off having a baby and we’ll use condoms. And I’m going to spend a lot of my spare time in the library. Working out a few things. Including why the HIV proteins occur in normal, healthy people. In fact I’m going to read all the original papers on HIV isolation and find out exactly what evidence international scientists published to prove there is a virus called HIV. Then I’m going to ask you to repeat my test.
Dr: And what if your test is still positive?
P: Then whatever caused it must still be operative. But that won’t prove it’s HIV.
TO BE CONTINUED..
ENDNOTES
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