William Parker er en svært erfaren forsker med hundrevis av vitenskapelige publikasjoner. Han har spesielt utpreget seg som en ledende ekspert på koblingen mellom invollsormer og menneskelig helse og har argumentert for at noen former for slike makroorganismer ikke er skadelige, men snarere ønskelige, naturlige elementer av den menneskelige biota, som kan ha en terapeutisk virkning i visse sykdomstilfeller. I dette intervjuet, gjennomført i 2017 av Eirik Garnås, deler han av sin ekspertise.
1. Who are you? What’s your profession and educational background?
I’m an associate professor at Duke University Medical Center. I’ve been studying inflammation in Western Society for the past 15 years. Although my PhD is in chemistry, my work for most of my scientific career has focused on immunology.
2. How and why did you get interested in Darwinian/evolutionary medicine and the human biome?
When we look at inflammation in Western society, it is obvious that we have done something to our environment to induce illness. This amount of sickness is not “natural” or “normal” for any species. This comes down to a fish-out-of-water model of disease (evolutionary mismatch).
3. What’s the main focus of your research?
We have a couple of things going. We are really interested in all of the modern factors which lead to inflammation. Most of our work focuses on “biota alteration” or “biome depletion”, or alterations in the community of symbionts of the human body. We have done some work with chronic stress, and vitamin D deficiency is something that we are becoming more interested in.
4. A large body of evidence suggests that a loss of biodiversity from the human superorganism (biome depletion) is a root cause of many human diseases and health problems. Can you briefly explain the core principles of the biome depletion theory?
The basic idea is that we have lost “keystone species” in the ecosystem of the human body. Without these species, our immune systems are not properly trained and are unstable. While processed food and antibiotics affect the microbes to a substantial degree, other factors such as toilets, refrigerators, and water treatment facilities have essentially exterminated helminths in our society. These changes, these alterations to our biome, are one of the key factors underpinning inflammation-related diseases in Western societies.
5. In 2013 you published an article entitled «Evolutionary biology and anthropology suggest biome reconstitution as a necessary approach toward dealing with immune disorders«. Could you briefly summarize the main points of that article?
That article was a spinoff of an earlier, shorter article published online in the Evolution and Medicine Review. Both articles explain the concept of biome depletion. Both articles advance the idea that public health cannot be achieved until we as a civilization recognize the importance of our symbionts for health and actively cultivate and protect those symbionts.
6. The microscopic (e.g., bacteria) part of the human biome has received a lot of attention lately. Besides microorganisms, which other organisms are a natural part of the ecosystem that has co-evolved with the human body?
Helminths and protozoans. We know that helminths are important, but the role of protozoans is a bit foggy. Protozoans could be classified as microbes based on their size, but they are being driven out by Western culture and are not generally considered in modern studies of the microbiota.
7. Not all worms and parasites do us good. Which ones are considered “old friends”?
Jeff Ollerton and I (Evolution, Medicine, and Public Health, 2013:89-103) point out that whether a helminth is beneficial or not to its host is dependent on a variety of factors. If a Westerner has multiple sclerosis, then a helminth might alleviate their life-threatening disease without causing any adverse effects. If someone in a developing country is on the edge of starvation, then the same helminth could end their life. In one case the helminth is a mutualist (beneficial), and in the other case it’s a parasite (harmful).
8. What are helminths?
Generally, intestinal worms. Sometimes people will refer to worms that live outside of the intestines as helminths, so the context is important.
9. How do we know for certain that worms were a part of the ancestral human biome?
There are two ways. First, we can look at non-human primates and find helminths there. Second, we can look at human cultures which are not yet Westernized and find helminths there. The studies with non-human primates are probably the most compelling, since modern non-Western cultures live in much more crowded conditions than did our hunter-gatherer ancestors, and that may have affected the transmission of helminths.
10. What happens when we lose touch with macroorganisms that have co-evolved with us for millions of years?
Based on all available information, it looks like the result is increased inflammation leading in turn to allergy, autoimmunity, neuropsychiatric disorders, and digestive problems. However, it’s important to keep in mind that other factors in Western culture (inflammatory diets, sedentary lifestyles, chronic psychological stress, and vitamin D deficiency) also drive the immune system toward this inflammatory posture.
11. Which role do helminths play in human health and disease? Why isn’t it sufficient to harbor a diverse, balanced microbiota? What functions do worms serve that microbes don’t?
It is fascinating that you asked this question. We are just now in the process of publishing a paper on this very question. In a nutshell, it seems that the microbiome is necessary to stimulate the development of the majority of the immune system, and that helminths are important for refining that system.
12. In your opinion, which non-microbial organisms are the most important with regards to human health and well-being? Have all of these been lost from the human biome?
It’s hard to say which are most important, and yes, they have all been lost. Maybe everybody needs a few roundworms (namatodes) as well as a flatworm (cestode) or two, or maybe just any helminth is fine for prophylaxis. Maybe protists (protozoans) would also work for immune regulation, but that’s speculative.
13. How can we reconstitute the human biome? Which strategies do you think would be feasible and effective?
At present, it looks like the most straight-forward course is to domesticate a benign helminth and artificially introduce that helminth into the population. Of course, we also need to take care of our microbiota. A healthy diet is key for that.
14. Do you think worm therapy will be a routine part of the treatment of some health conditions in a not so distant future? If so, which diseases do you think will respond well to this type of intervention?
Based on available evidence, treatment works best for autoimmune conditions and neuropsychiatric conditions that are episodic. Persistent conditions may be harder to treat, and allergies may only be treatable if the patient is not regularly exposed to the offending antigen. But of course we won’t know until definitive studies are conducted.
15. Do you think drugs containing helminths and other macroscopic organisms will soon become available on the market? If so, when can we expect this to happen?
It is our published viewpoint (Medical Hypotheses,77:494-504) that attempts to make a drug from helminths are misguided. It is impossible to recapitulate system/system interactions with drug/system interactions.
16. Besides efforts aimed at reconstituting the human biome, which other interventions do you consider to be essential for improving public health?
We need to deal with all five of the big five problems. Besides biota alteration, chronic psychological stress, sedentary lifestyles, inflammatory diets, and vitamin D deficiency need to be the highest priorities for our health care system. If we don’t address all of these issues, the best we can ever hope for is a sick-care system that treats disease, not a health care system that protects the population health.
17. Anything else you’d like to add?
Thank you very much for the opportunity to express my views!
Mer fra William Parker…
Utvalgte vitenskapelige arbeider
- «Intestinal worms eating neuropsychiatric disorders? Apparently so.«
- «A model for the induction of autism in the ecosystem of the human body: the anatomy of a modern pandemic?«
- «Got worms? Perinatal exposure to helminths prevents persistent immune sensitization and cognitive dysfunction induced by early-life infection.«
- «Evolutionary biology and anthropology suggest biome reconstitution as a necessary approach toward dealing with immune disorders«
- «Reconstitution of the human biome as the most reasonable solution for epidemics of allergic and autoimmune diseases!«