Can Dirty Mean Healthy?

I must preface this by paraphrasing Star Trek and saying, “Damn it, Jim; I’m a collection manager, not a doctor.” Ask a real one for further guidance.

In the 1950s, scientists noticed a relationship between our North American increasingly cleanliness-obsessed urban lifestyle and a rise in diseases such as asthma, arthritis, multiple sclerosis and diabetes, as well as allergies such as hay fever, most almost unheard of 100 years before. These are known as auto-immune disorders, caused when something triggers our immune system to attack an organ or function inside us as if it were an invading enemy. People living in areas with childhood exposure to a broader range of microbes don’t suffer the same incidence of these syndromes in adulthood. One common thread appeared to be the presence or absence of intestinal worms.

This observation developed into the Hygiene Hypothesis, also known as the Old Friends Theory. I had the opportunity to present the subject and discuss it with the audience at a recent NatureTalks evening, held at the museum on April 16, 2014.

We are learning that the experiment we have been running in the developed world by eradicating many of our “pest” species is not altogether successful. The very species we have tried so hard to avoid may have been conferring a healthy reward for their room and board.

Over millions of years of evolution together with our parasites, by the grace of the much faster generation time of a short-lived worm and the trial-and-error system of natural selection, parasites have refined ways to avoid, evade or alter our immune systems. Early childhood exposure to contagion, through farm animals, pets (interestingly, dogs but not cats) or even older siblings, leads to a dampening down of immune response. We may have “contracted out” this service to our parasites and biologically assumed they would always be with us to perform this function.

An interior view of an intestine.

An interior view of the intestine in a patient with the human whip worm (Trichuris trichiura), a possible future treatment for multiple sclerosis. Image: CDC/Dr. Trenton Ruebush © Public domain; made available by CDC Public Health Image Library (PHIL)

Ongoing trials are testing whether intestinal worms can alter the symptoms of several of these auto-immune syndromes, with impressive results. In early studies, using worms from pigs that don’t live long in humans, nearly 80% of patients with Crohn’s disease reported significant reduction of their symptoms after 24 weeks of treatment. Further tests are determining which species of worms can help patients with other autoimmune problems such as arthritis, multiple sclerosis and asthma.

Pharmaceutical companies would dearly like to find out why and precisely how this works so they can isolate a specific molecule for market, but the mechanism is so complex that scientists still aren’t entirely sure about the human immune system pathways and worm chemicals involved.

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The human hookworm (Necator americanus) is being investigated as a treatment of inflammatory bowel disorders in humans. Image: Jay Reimer © Jay Reimer (shared under licence CC 2.0 https://creativecommons.org/licenses/by-nc-sa/2.0)

Not only have we eradicated our worms, but we have also greatly reduced the number of species of bacteria and fungi which live on and in us. Lower diversity in any ecology is dangerous and can lead to imbalances, sometimes with alarming speed and consequences.

This has become more evident with the rise of antibiotic resistance in bacteria such as Clostridium difficile. Until recently most infections were picked up in hospitals where their durable spores linger in the air or on surfaces but many people now have a small number of “C. diff” bacteria in their gut. Antibiotics taken for an infection wipe out not only the sinus inflammation or bladder infection they meant to treat, but also all the good gut bacteria, freeing C. difficile to run rampant causing painful and persistent diarrhoea.

A bacterium.

The bacterium Clostridium difficile produces toxins that induce painful intestinal symptoms when it infects the human intestine. Image: Jennifer Hulsey © Public domain; made available by CDC Public Health Image Library (PHIL)

Although some people can be cured with more antibiotics, the rate of reoccurrence is very high (20% to 35%), causing long periods of suffering and loss of strength, often fatal in the elderly. The best way of treating C. difficile turns out to be transplantation. Not of body parts, but of body content! The poop from a healthy donor is mixed with water and inserted via a nasal-gastric tube or enema into the infected person, restoring a normal intestinal ecosystem. The success rate is about 90% and patients feel better often within hours. It may sound gruesome, but it works.

There are other experiments underway to help us deal with antibiotic-resistant bacteria. Some proposals are as mundane as adding probiotic bacteria to our water supply to increase our interior diversity. Others are looking at new targets on bacteria and viruses at which we can aim vaccines, and naturally occurring antibacterial agents like host defense peptides and bacteriophages.

In the meantime, the best thing you can do is wash your hands well and often with plain soap and water. Antibacterial chemicals in cleaning products will only select and allow to thrive those bacteria that are resistant to their effects, and often continue to kill good bacteria in the environment after flowing down the drain. Consider buying locally pastured meat raised without antibiotics. Ask your doctor if you really need a prescription for antibiotics or if rest and fluids will help you ride out an infection. Stay home from work or school while sick to help your colleagues avoid contagion. Take advantage of the herd-immunity principle by keeping your vaccinations up to date. Let your kids get good and dirty.

Read more about other NatureTalks events:
Deliberating De-extinction
Hybridization in the Living World
My Thoughts on Thinking Plants

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