One of the most prominent proponents of the claim that HIV is not the cause of AIDS, Peter Duesberg claims in a PNAS article from 1989 the following

The hypothesis that HIV causes AIDS is examined in terms of Koch's postulates and epidemiological, biochemical, genetic, and evolutionary conditions of viral pathology. HIV does not fulfill Koch's postulates

Koch's postulates are the follwing according to Wikipedia:

  1. The microorganism must be found in abundance in all organisms suffering from the disease, but should not be found in healthy organisms.
  2. The microorganism must be isolated from a diseased organism and grown in pure culture.
  3. The cultured microorganism should cause disease when introduced into a healthy organism.
  4. The microorganism must be reisolated from the inoculated, diseased experimental host and identified as being identical to the original specific causative agent.

Are Koch's postulates, formulated in the late 19th century, a valid principle for evaluating if HIV causes AIDS?

  • There is an updated version for the 21st century in the wikipedia article: en.wikipedia.org/wiki/…
    – Tjaart
    Commented Aug 15, 2012 at 6:15
  • Does a virus even qualify as a micro-organism? They can't reproduce without molesting a cell's genetic makeup, they don't have any metabolism, they can't move under their own power, they don't grow, etc etc etc
    – GordonM
    Commented Dec 24, 2018 at 13:22

2 Answers 2


Tellingly, Koch himself eventually abandoned the strict postulates!

Other than that, there are heaps of known virus infections that are exceptions to the postulates. I wouldn't pay that much regard, and it is my understanding that nobody does.

Although I don't think failure to fulfil the postulates proves anything, it turns out there's actually still some debate as to whether or not the HIV->AIDS causation does. I'm afraid I can't read the full article, but clue is in the title :)

  • 4
    That article is an editorial claiming that the accumulated evidence now shows that the HIV -> AIDS connection now fulfills Koch's postulates. They're cheating a tiny bit as they use documented cases for the requirement that HIV introduced into healthy individuals should cause AIDS, instead of doing a study infecting healthy persons with HIV. That kind of experiment would obviously be highly unethical.
    – Mad Scientist
    Commented Feb 28, 2011 at 21:29
  • Thanks for that input, @Fabian! And yes, it would be :) Regardless, I find that to be of less value than the fact that there are many known virus infections that do not fulfil all postulates. It seems commonly accepted that this is not a prerequisite to infer causation. Commented Feb 28, 2011 at 21:51
  • 1
    @Fabian: They can infect non-human primates with SIV.
    – Golden Cuy
    Commented Mar 1, 2011 at 12:54
  • Yea. THey can infect non human primates with SIV. Have this been done.
    – user4951
    Commented Sep 12, 2012 at 9:28
  • Could you post examples of virus infections that are exceptions to the postulates?
    – Stefan
    Commented Sep 13, 2012 at 13:12

Just from reading the Wikipedia page of Koch's Postulates, several flaws in them are immediately identified.

The first postulate ignores asymptomatic carriers, which Koch himself acknowledged. So an argument that some people have HIV but not AIDS shouldn't discount the HIV->AIDS causation.

The second postulate assumes that microorganisms can be grown in a culture. I'm no microbiologist, but I don't believe this is true of viruses - they need to be in living cells to reproduce.

The third and fourth postulates require infecting a healthy host, which is unethical in terminal diseases that affect humans and not lab animals.

  • Viruses are also cultivated in bacteria.
    – user8150
    Commented Aug 12, 2012 at 21:40
  • @user8150 - Yes, but that can only be done with virus that infect bacteria.
    – Pere
    Commented Dec 23, 2018 at 20:17

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