Autism is more than a parasite deficiency

The New York Times Sunday Review had an article this week linking autism with the hygiene hypothesis. Written by Moises Velasquez-Manoff, the piece is part of the Times' opinion coverage, not reported news. It was also one of those sort of stories that comes across as highly persuasive ... until you start looking at the details. About halfway through reading it yesterday, it occurred to me that Velasquez-Manoff was making a lot of big statements—"perhaps 1/3 of autism, and very likely more, looks like a type of inflammatory disease", for example—without citing the sources to back those statements up.

That's easy to do when you're writing a relatively short article summarizing the contents of a much bigger book, as Velasquez-Manoff seems to be doing here. But the problems go deeper than that, according to biologist and science writer Emily Willingham. In a must-read blog post, she goes through the NYT piece and points out many flaws in argument and detail. The main problem, though, is a pretty simple one: Moises Velasquez-Manoff presents what seems to be a largely speculative hypothesis as sure-fire truth. To make that case as persuasive as it is, he leaves out lots of evidence that doesn't match up with his thesis.

First, he appears to describe autism as a “parallel epidemic” with autoimmune diseases, even though a careful review of the literature shows that there likely isn’t an “epidemic” of autism. I'm also having trouble finding any data to confirm an epidemic of autoimmune diseases (he provides no sourcing), although I find that incidence rates in general seem to go up with improvements in diagnostic tools, a scenario that is common with application of new technologies in many diseases and disorders. Without that parallel or even confirmation of either "epidemic," his carefully constructed, fragile “if that, then this” scenario suffers from that point on.

...Velasquez-Manoff then asks, “What has happened to the modern immune system?” and goes on to assert that the concepts underlying the “hygiene hypothesis” also underlie autism and correlations between autism and maternal autoimmune disorders or asthma. An “evolutionary answer,” he says, is that we are no longer sufficiently riddled with parasites and microbes (we actually still have our microbes), so our immune system, twiddling its presumably heroic thumbs, casts its roving eye elsewhere--i.e., on ourselves. See, people who still live with parasites, he says, “don’t suffer from inflammatory diseases as much as we do” (italics mine). “We,” I assume, being the clean people of the western world. No sources given, and that assertion does not dovetail with, for example, what we know about asthma rates in Latin America (really high) versus Western Europe (not so high), although in places where things like leprosy, parasitic worm infections that include river blindness, and nasty bacterial eye infections are high, type 1 diabetes is low. Raise your hand if you're willing to make that tradeoff. And then he says, “Autism also follows this pattern” and “seems to be less prevalent in the developing world.”

... when you’re dealing with intestinal parasites and their friends, you and your government may not really have the time to go around carefully diagnosing developmental disorders. I suffered through his unsourced dismissal of epidemiologists who say as much, and I just about had a coronary when he cited “at least one (unnamed) Western doctor” (the best kind, you know) who had found autism was “nearly nonexistent” in a Cambodian population “rife with parasites and acute infections.” Um… if, as Velasquez-Manoff seems to argue, maternal infection sets the stage for maternal immune dysfunction and presumably autism, how is it that a population rife with acute infections evades autism? He doesn’t ever name the “Western doctor,” but autism does exist in Cambodia, and while we’re at it, here are a few other things Cambodian children must endure because they’ve got this great “evolutionary”-based existence that 'protects' them against autism.

Willingham's basic point: There is an atmosphere of desperation and panic surrounding autism, which has lead some parents to try a range of risky interventions in the hopes of "curing" it. Given that, maybe it's irresponsible to claim that a hypothetical factor in autism is the absolute cause. Especially when the proposed treatment—intentional infection with parasitic whipworms—comes with its own downsides, including growth retardation in children, anemia, and even rectal prolapse.

Read the New York Times op-ed

Read the rest of Emily Willingham's response


  1. As much as parents would like to cure autism or prevent seemingly healthy newborns from “catching” it, I thought the current consensus is that:

    1) Autism is innate – children are born with it but it only shows up in later development – similar to schizophrenia. 

    2) A proximate “cause” of autism is a large excess of neurons in the brain. Children are born with the excess neurons which only cause problems as they develop.

    3) Any search for environmental (and  maybe genetic) causes of autism should focus on the health of the mother not the child.

        1. Are you unable to use teh Google?

          DBAD.  You made the claims, you’re responsible for supporting them.

    1. Yeah, citations would be appropriate here given the subject of the OP.  Also, (2) sounds fishy to me…all human beings are born with an excess of neurons which are then “pruned” during the course of development.

      Also, on (1)…it’s my understanding that childhood schizophrenia is EXTREMELY rare (I think there was a recent BB post on a case) — it usually develops between 18 and 22. ASD folks seem to exhibit symptoms very early in life. Source (This does reinforce your third point.)

      1. My understanding is that while it is extremely rare to see a child with full-blown schizophrenia, we are getting better and better at identifying children who are predisposed to the disease.  However, I do have to disagree with MonkeyBoy that it is innate.  Research is beginning to show that stress management techniques and prophylactic medication can prevent the initial psychotic break that leads to schizophrenia –

        1.  I wasn’t arguing that it wasn’t innate; I think a lot of heritability studies are bullshit but the data on schizophrenia looks pretty sound.  I was just pointing out that “ASD is a lot like schizophrenia” is a bit of a stretch.

    2. 1) the fact that it’s “innate” doesn’t preclude it being cured.   Congenital defects and molecular defects can be effectively “cured”.  ASD and PKU are two common examples. 2) that’s one finding, and one theory, it’s not been determined to be the most significant effect of causation.   3) conditions can be a combination of environmental stresses on mother and autism.  Schizophrenia is a good example of a condition where both the child and the mother’s environment have been posited to have a contribution.

      1. > ASD and PKU are two common examples. 

        Two “common examples” of what? The validity of the word “cure” in autism is hotly debated. It’s not a “common example” of anything — it’s a very idiosyncratic example of a condition diagnosed by subjective clinical observation, with no gold-standard biomarker, so yes, while many children “lose the diagnosis” over the years, that doesn’t mean that their underlying neurology has been transformed, as the word “cure” implies.

        1. I thought it odd that the original poster was focused on autism being innate vs. acquired postnatally, as if that had ramifications for something being curable.  I gave two examples of innate or congenital issues that were curable.  In PKU, the underlying neurology in prevented from being transformed.  It is unclear if there will ever be anything similar in autism. 

  2. It’s just a journalism problem, where science stories are seen as having a beginning, middle and end, nicely wrapped up. Every week brings a new cure for cancer. The truth is messier than that

  3. Inflammation seems to be the latest fad cause of all medical problems.  I’ve heard radio commercials advertising special krill oil supplements that have more anti-inflammatory power than any other omega supplement!!!!

  4. I don’t know much about the parasitic infections these people are giving to their children, or the conditions involved (though I’m dubious), but it’s worth pointing out that these and similar infections are a huge problem in the developing world, stunting and strangling not only individuals but effectively whole societies.

    For more information, see

  5. Best i can tell, autism has always been with us. But with the industrial revolution, and the drive towards sitting still and taking orders, the non-obvious end of the spectrum (hello Aspergers) have become obvious. I wonder how many lonely farmers out on the edge of the village, or frontiersmen beyond the edge of western civilization were on the aspie end of the autism spectrum.

    1. If those people are anything, it’s on the asocial end of the neurotypical spectrum. Asperger’s isn’t a quirk, it’s a clinically significant deficit. If you merit a diagnosis, it’s not to cover up being awkward, or to proclaim your smarts (WTF, Zuckerberg?!?), or to justify being rude and insensitive.

      If you meet and spend time with kids in the mild/moderate part of the spectrum, you gain a much clearer understanding of Asperger’s; I think it’s harder to see the line when you start from the fat part of the bell curve.

      1. And with the world becoming more and more about face time and marketing oneself, no wonder it starts to stick out like a sore thumb.

      2. What’s the difference between “insensitive dick,” and “Asperger’s syndrome?” Just a checkbox on a diagnostic form? 

        I’m not saying that we should assume that kids diagnosed with Asperger’s or autism are “just being dicks,” but perhaps when you run into someone who seems to be an insensitive jerk, you might consider he just doesn’t see things the same as you?

        Reminds me of a documentary I saw on Mark E. Smith, wherein someone who knew him was describing his behavior to a psychiatrist friend, who responded that he was describing textbook case of schizophrenia – then the man added that Smith had recorded over forty albums and successfully managed an income stream from a series of bands, and the psychiatrist immediately recanted, saying that, by definition, no schizophrenic can be that successful. 
        Similarly, there are people, who definitely fit most of the definitions of Asperger’s or somewhere on the autism spectrum, but they’re too successful to actually get a diagnosis.

        1. That is exactly my point: if you actually have these problems, you are likely burdened with tremendous difficulty functioning on a day-to-day basis.
          The high-functioning Aspies who are driving the neurodiversity movement are perhaps at the edges of the zone of overlap — it’s not my area of familiarity and I expect that many of those folks have compensated greatly for their differences.
          If you are successful at neurotypical behavior, then you’re likely not diagnosed, or shouldn’t be. After all, if you’re in that fat part of the curve — figure 2sd from the mean, at least, you’re effectively “normal but quirky.” (Cf. the notion that we all have cancer but very few of us have tumors.)
          There’s a real qualitative difference in people suffering from biological disorders and those with poor social skills from other causes.

          1. One can pass for NT, but it will drain mental and physical resources fast by doing so. And with a workplace that offer less and less chance to retreat and recharge, well…

  6. I actually found the Times article a lot more persuasive than the so-called debunking of it by Willingham. The Times article didn’t read like a junk science article — it was a reasonable, interesting and somewhat optimistic attempt to connect a lot of dots to find a broad theory for autism. It isn’t Valazquez-Manoff’s fault if crazy people take his science and use it for their own crazy purposes. (Meanwhile, I find Willingham’s statement that autism isn’t actually an epidemic a lot more questionable than anything in the Times article. Valazquez-Manoff addresses the likelihood of over-diagnosis, while Willingham pretends that over-diagnosis is the whole story.) For another thing, Valazquez-Manoff’s idea that autism is caused partly in the womb has popped up in other studies, including one that noted a higher incidence of autism among fraternal twins than normal siblings. 

    Willingham also blames the article for attitudes it doesn’t display, such as “blame the mother” (which it doesn’t) and “Let’s all put worms in our bodies!” which the article proposes as one intriguing possibility, but doesn’t necessarily advocate. The article certainly doesn’t embrace a fantasy-land in which people in Third World countries are actually healthier. I actually found Willingham’s attack on the article strangely defensive. Willingham’s basic argument was, “This guy isn’t sure he’s 100% correct but writes like he is!” Isn’t that what happens when anyone proposes any new big theory? 

    1. It’s not “overdiagnosis” when people who wouldn’t have qualified under the old criteria qualify under the new criteria. And that’s a huge chunk of it – nobody’s keeping stats on “just the subset who would have qualified under the old criteria”, and the new criteria is broader.

      You can’t compare the two numbers. It’s like saying “Well, this census from 1920 says that 20% of the population were over 65, and this years census says 45% of the population are over 50! Oh god, there’s an epidemic of senior citizens!” Well, no. The two numbers aren’t comparable at all – the folks over 50 aren’t all senior citizens, the seniors are just a subset of that. You can’t tell if there’s more people alive over the age of 65 with that metric.

      And the broader diagnosis is the only modern metric we have stats on.

      You can’t claim epidemic based on no stats. That’s scaremongering, right up with yelling “FIRE” because I can’t prove there isn’t a fire.

      Willingham’s basic argument was, “This guy isn’t sure he’s 100% correct but writes like he is!” Isn’t that what happens when anyone proposes any new big theory?

      Um, actually, no. No, that’s not what happens when “anyone” proposes a new big theory. When a sane, sensible, scientist proposes a new big hypothesis, he says “I think it might be X but I’m probably wrong, because wow that’s a big jump. Can someone double check my numbers?”

      This isn’t a theory yet.

      1. Have you read the Times article? The exact phrasing the author used was, “At least a subset of autism — perhaps one-third, and very likely more — looks like a type of inflammatory disease.”  Saying something “looks like a type of inflammatory disease” (not that it “is” a type of inflammatory disease) sounds like a reasonable statement of a hypothesis to me. It is Willingham who accuses the author of denying the existence of any counter-arguments. That’s why I’m inclined to be more skeptical of her attack on the article than the article itself — because her attack is a misrepresentation of the original article.

    2. > Willingham pretends that over-diagnosis is the whole story

      Even beyond your loaded use of the verb “pretends,” Rachel, this is simply incorrect.  As the mother of an autistic child, Willingham is hardly a partisan of the notion that autism is currently “overdiagnosed.” The word you’re looking for is not “overdiagnosis,” but “diagnosis.” 40 years ago, diagnostic categories like Asperger’s syndrome and PDD-NOS didn’t even exist in the DSM. In other words, the huge numbers of people who are now diagnosed with those conditions would have been misdiagnosed with something more like schizophrenia or neurosis. The role of those numbers in the overall “spike” in autism diagnoses is what people like Willingham and many others are talking about.

      1. Actually, you just cleared up something for me. I didn’t know that Willingham had an autistic child, so I found her tone about the article weirdly defensive. Now it makes more sense. When the author of the Times op-ed implied something might be going on in utero to cause autism, Willingham took this to mean the author was somehow indirectly “blaming” her and other mothers for her child’s condition — a pretty serious and emotional charge. 

        I didn’t take read article that way at all, because I have no personal horse in this race — but I can see why that would make her read the article in such a hostile way — and take from it a tone that seemed so different from the tone and spirit in which I read it. She’s certainly not an unbiased scientific observer of a study that traces autism to something that’s possibly preventable (at least in theory) in the mother.And for what it’s worth, it’s still obvious autism has genetic roots, of course. But perhaps the genetic roots involve a susceptibility to certain increasingly common conditions. Frankly, I think people are so used to the idea that “we don’t know what causes it” that a non-quack possible cause makes some people angry.

        1. Yes, I’m sure her reaction is entirely because she feels blamed by the article for having an autistic child and thus she is much more biased than someone who writes a one-sided article about their germ theory hypothesis they will expand on in their upcoming book (that maybe you should buy!) that ALL the evidence shows is true, contrary to the entire history of scientific observational studies in every single field.

          She’s the biased one, because autism.  

          1. Let me give an example. The Times op-ed piece says, more or less, “A Western scientist noted that autism is virtually unknown among children in Cambodia who have substantial parasites.” (Not that such children were healthier overall, just that they had less reported autism, according to one Western scientist.) So Willingham replies, “There is autism in Cambodia!” and provides a link. So I looked at the link, assuming it would provide substantial data, and it was a single reference to a single Cambodian child on an adoption website, and the Western adoption agency claimed that they thought the child might have autism. 

            This suggests to me that Willingham was frantically googling anywhere she could in order to create a point-by-point retraction of the original opinion piece. So yes, I think she’s the less trustworthy source, here, and that she was reacting emotionally. Citing a single case of a possibly autistic child as “proof” is not evidence of strong scientific reasoning. If she’d said, “This is an interesting argument, but it’s unlikely, and here’s why,” I’d have trusted her reasoning a lot more.

          2. Your criticism is simply that she wasn’t scientifically rigorous in illustrating why the article which presents itself as science is not scientifically rigorous. It’s not an interesting article because it’s almost complete junk cobbled together into a Frankenstein’s reminiscent of the vaccine debacle that autism is STILL fighting after twenty years.

            You are literally holding her to a higher standard than you are holding the article because she has an autistic child instead of a book to sell.

    3. Yeah, that was my take too.  Willingham also seems to suggest that because he’s using the phrase “inflammation” in the same paragraph as autism, he’s a anti-vaccine.  No.  The inflammation model of autism is just one theory, it doesn’t hinge on vaccine being the cause.  Mainstream scientists, like Zimmerman of Johns Hopkins and Kennedy Krieger are pursuing it. 

  7. For Rachel:  Not surprising you found it “persuasive”.  It’s an opinion piece, and it reads like one.  Not like a piece persuading you with actual good, well documented science, but with sweeping statements and generalizations without having to provide evidence or balance.  That is Willingham’s point – it is opinon masquerading as science, so she is holding it to the standards of scientific writing.   And it fails.

  8. Willingham’s piece suffers from the EXACT same flaw that she criticizes in the NYT piece.  When she says autism exists in Cambodia, like this somehow is proof that the NYT author’s point is faulty, she fails to support her assertion with any actual data.  

    The idea that people in populations with higher incidence of parasites would have zero incidence of autism is not proposed in the NYT piece where they suppose (without cited proof or evidence) that 1/3rd of the cases of autism are caused by some kind of misfiring maternal immune response.

    I agree that the NYT piece glosses over the science.  

    If you want the scholarly work on the topic of autism and immune dysfunction, it’s relatively easy to find.  And it’s plentiful. 

    I just think it’s an interesting idea…that we work better with some parasitism…or perhaps symbiosis?  

  9. We do know that about 1/3rd of the rise in Autism is probably due to the age of the father at conception, which has also been rising.

    And, no, this isn’t like the ‘Pirates cause global warming’ correlation .. there’s a nice paper in ‘Nature’ on the subject.  The cause in those cases seems to be an increased rate of de novo mutations.

    I don’t have a link to the study – but here’s a summary of some of the findings:

    1. That is completely NOT what that study is saying.  It describes a correlation found between a specific type of mutation and autism. It then looks at other possible correlations to exclude them as possible explanations for their data. “To determine whether factors other than diagnosis of ASD could explain our findings, we examined a variety of potential covariates, including parental age, IQ and sex.” It then said that even though there was a correlation between paternal age and the mutation, it did not alter their results. That study is absolutely NOT saying that paternal age is CAUSING autism. Or anything remotely close to that.

  10. Of course, Moises Velasquez-Manoff wouldn’t stand to gain from penning this op/ed piece via sales of his new book.  Oh, wait…

Comments are closed.