To Worm or Not to Worm, That is the Question

Are we too clean? Are we leaving our immune systems compromised by not challenging them enough with dirt, bacteria, and parasites such as the Hygiene Hypothesis postulates? Allergies have doubled since the 1970’s leaving 54% of the population in the U.S. with at least one allergy according to researchers at the National Institute of Health as published in the August issue of  the Journal of Allergy and Clinical Immunology. The lead researcher, Samuel Arbes, stated there has even been a period where asthma increased 74%.  There is also a  significant difference between the allergy and asthma rates of those living in Urban areas as compared to rural areas and under developed countries…people in urban areas have much higher rates of allergies and asthma. Studies show that worms and parasites might be the answer to keeping the ever-increasing autoimmune disease epidemic in developed countries, and in fact, are currently being used to treat ulcerative colitis and Crohn’s disease.

Worms of endearment

Issue 2 of Cosmos, August 2005

By Abbie Thomas

There’s an allergy epidemic sweeping the Western world. Could eating worms save us?It seems that everywhere you go, you hear the sound of sneezes and wheezes. From peanuts to cats, house dust mites to grass, horses to cockroaches, an epidemic of allergies is going around.

Credit: Sonia Krestchmar/COSMOS

Yet the change is alarmingly recent: in the space of only 50 years, as many as 40 per cent of Australian children now have an allergy to something; one in five school-aged Australians has chronic asthma. And it’s a picture repeated around the affluent world.

A century ago, cholera or diphtheria might have been the rising threat, but these have been largely banished by antibiotics and sanitation. Now allergies are on the rise – ironically, a threat that may be an unintended consequence of the triumph over the infectious diseases.

They may be the diseases of the modern era: but there could be a solution that goes back to our most primitive lifestyles.

The ‘hygiene hypothesis’, an idea put forward in 1989 by David Strachan from the London School of Hygiene and Tropical Medicine, attempts to explain the cause of this allergy tsunami. It argues that the human immune system is no longer suited to our modern, hygienic world.

 “Our immune system evolved in the presence of infections and found an optimal way to live with it,” said parasite researcher Anita van den Biggelaar from the University of Western Australia. “This was a balance between immune responses that protect against infections, versus responses that down-regulate hyper-reactivity [in order to avoid allergic reactions such as asthma].

 “Allergens only became as issue when people started to live in an infectious-free environment, when our immune system no longer matched the environment it was made for,” she said.

Consequently, when we breathe in an innocuous object – like a pollen grain or flake of cat skin – many people have a dramatic allergic reaction, far in excess of the danger posed by the allergen.

There are scant clues for why some people develop asthma and allergies while others don’t. But if you spent time in child care, grew up on a farm or were not the first born child, you are far less likely to be a sufferer.

While these links have been known for some time, a new and bizarre clue to the puzzle of the allergy epidemic in Western society is emerging from studies of African children.

Dr van den Biggelaar has found that Gabonese children infested with worms seem to have fewer allergies. Could the worms be protecting these children against allergies? To find out, she wormed some of the Gabonese children, then tested them for sensitivity to house-dust mite every six months for five years.

Those children who had been treated for worms became much more sensitive to house-dust mites, which suggested the worms were dampening allergic reactions: preventing hypersensitivity to allergens such as dust mite as a ‘side-effect’ of the suppression of the host’s immune system that is essential to their survival.

But how? “That is something we unfortunately have not shown yet,” says van den Biggelaar. One thing she has established is that worm-infected children tend to have a lot of interleukin-10, a chemical produced by certain cells, which suppresses the immune system.

Interleukin-10 (also known as human cytokine synthesis inhibitory factor, or CSIF), is a small protein that exhibits anti-inflammatory properties by virtue of the fact it helps inhibit synthesis of inflammatory signals between immune system cells.

Another theory is that T-cells in the immune system may be suppressing other cells normally responsible for attacking invading organisms. While this may sound contradictory, if you have to live with a chronic worm infestation for years, you don’t necessarily want to have constant inflammation, or you could end up with an autoimmune disease.

The immune system might therefore be dampening itself down in order to ‘damage control’ the side effects of a long-term worm infestation.

So the question arises: could worms be used to treat asthma and allergies? The evidence is growing in support of this proposition; several eminent scientists think so.

 For the past several years, Alan Brown of Britain’s University of Nottingham has relieved his chronic hay fever by allowing a modest community of hookworms to live in his gut. While they do cause anaemia, he says, a healthy western diet more than compensates for the loss of nutrients.

 Meanwhile in the U.S., parasitologist Joel Weinstock from the University of Iowa is using pig whipworms (Trichuris suis) to treat a chronic bowel disorder called ulcerative colitis. People with this disease have immune systems that are so overactive, they literally attack and breaks down the gut – as if they were ‘allergic’ to themselves.

Every three weeks, Weinstock’s patients drink a glass of tonic with some worm eggs mixed in. These hatch and attach to the lining of the intestine, where they force the immune system to produce cells that dampen immune reactions, reducing the inflammation that makes this disease so painful.

The worm infection can’t get out of control because the pig whipworm doesn’t reach adulthood in humans.

Another treatment based on this worm species is being used for ulcerative colitis and Crohn’s disease, another chronic inflammatory disease of the digestive tract. Called TSO (short for Trichuris suis ova), it is being sold by Ovamed, a German pharmaceutical company.

Ovamed says the treatment is seeking drug approval from the European Agency for the Evaluation of Medicinal Products, after which it will be distributed in Europe, Australia and New Zealand by another German company, Dr Falk Pharma.

Infectious diseases expert Phillip Cooper from St George’s Hospital in London has also found that worms confer some resistance to allergies, after studying the effects of worming Ecuadorian children against the roundworm Ascaris. However, he believes that the use of live worms for treatment is unlikely to become widespread “because of problems with cultivating and preserving adequate quantities of viable larvae and eggs”. Never mind the gross-out factor!

But Cooper does say that understanding how worms control allergic reactions could help develop drugs that target specific pathways in the allergic response.

Van den Biggelaar agrees that worm-allergy studies are most valuable where they improve our understanding of the mechanisms of infection – the research has shown, for example, that immune-response deregulation is involved.

There are also lessons for treating people in developing countries. It would be a disaster if worm infections were eradicated, only to result in an epidemic of allergies like that seen in the West. New vaccines are needed, van den Biggelaar suggests, that control infection while still allowing the immune system to do its job of preventing allergies. This will, however, be complicated by the fact that some vaccines don’t work in people who are infected with worms.

Not everyone is convinced. “I think the evidence that worms protect you from allergic disease is pretty soft … when you make an observation, there are other explanations,” said asthma specialist Ray Mullins from the John James Medical Centre in Canberra, Australia.

“With allergic diseases, the die is cast early in life. If intervention were to occur, it would have to happen during infancy,” said Mullins. “It’s not sufficient to say, ‘Hey, this is the Holy Grail’. If we start giving our kids worms when they are born, I think that’s a bit simplistic.”

To worm or not to worm? It will take some time to be certain whether the science holds true. But it can’t hurt to keep studying those critters.

Thomas, Abbie.  “Worms of Endearment”.  Cosmos.  26 September 2006.  Web. 29 September 2011.

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