The CBC documentary The Allergy Fix examines the process of allergy desensitization.JOHN COLLINS
For William Comay, a peanut a day keeps a life-threatening food allergy at bay.
Just over a year ago, this six-year-old boy from Oakville, Ont., couldn't ingest 1/100th of a peanut – equivalent to a tiny fragment on a kitchen counter that could end up in a birthday cake – without having a severe reaction that might start with a tummy ache, slurred speech and choking cough.
Fortunately, William is among the first Canadian children to receive immunotherapy, which desensitizes the immune system to the point where a patient can tolerate small amounts of foods that used to trigger anaphylaxic shock.
Researchers working in Canada, Europe and the United States are on the verge of finding effective treatments for allergies to peanuts, milk and other foods, according to The Allergy Fix, a documentary airing Thursday on CBC's The Nature of Things.
In the episode, Vancouver-based filmmaker Bruce Mohun interviews Canadian patients who have undergone the desensitization process, including Avi Segal, who worked his way up to a dose of five peanuts a day, and explores the leading theories for why food allergies have more than tripled in the past two decades.
On the line from Vancouver, Mohun explains why immunotherapy, the peanut patch and even hook worms hold promise for food allergy sufferers worldwide.
How does food allergy desensitization work?
It's training the immune system so that you'd get a very small amount [of the allergen] over a period of time. Once a day, William would have roughly 1/100th of a peanut, or just underneath the level where he would react. He would get that every day for a few weeks and then they'd bump him up to 2/100th of a peanut for a couple of weeks. With the gradual increase, the immune system begins to accept that food as being normal.
Are many Canadian allergists offering this therapy, or is it too experimental?
Most are not. There's been a warning from leading American allergist Dr. Hugh Sampson that this should only be done in a controlled situation in hospitals, not in doctors' offices. Back in the early 1990s, at [National Jewish Health] hospital in Denver, a child died in a desensitization project. But Dr. Gordon Sussman, who desensitized Avi Segal in Toronto, says he has an emergency department in his building and he is confident that he can do this without any danger to his patients. Doctors can try this if they feel that the patient is a good candidate for this kind of desensitization. It's a risk-benefit thing.
How broad is the consensus that desensitization is the best way to treat severe food allergies?
I think it's generally accepted among immunologists worldwide that desensitization will be a successful way of [treating] kids. In a large study that came out of Cambridge University about a month ago, the researchers showed it was successful. But it's not a cure, because it looks like every time you go off the daily dose of the allergen, the allergy comes back.
Why did you look into hook-worm parasites as an allergy treatment? Isn't that way out in left field?
Well, there are two people on this planet who are selling allergy treatments using hook worms. The leading scientist in this area, Dr. David Pritchard at the University of Nottingham, said there's a certain danger related to that. But he is going to use it to treat patients with multiple sclerosis, which is also an immune disease, as a test case. There's a lot of evidence to show that the presence of worms in our bodies is protective against allergies. The solution isn't necessarily that we're going to have those worms put back in our bodies, but we'll understand a lot more about how the immune system works.
Explanations for the rise in food allergies include the hygiene hypothesis, increased pollution, less exposure to farm animals and changes in the makeup of gut bacteria – the microbiome. Are any of these theories winning out?
It's a progression of theories – there's not a lot of controversy in this field. Everybody feels that we need to continue studying how the microbiome affects the immune system and we have to see what antibiotics are doing to the microbiology. There's research on unpasteurized milk – what are the germs that we are killing that might be beneficial to us? And the idea of feeding allergenic foods to children just after they are weaned is linked to that, the idea that we need to expose the immune system to allergens.
Tell me about the peanut patch. It's worn on the skin, like the nicotine patch, but how is it safer than desensitization?
When you give kids an oral dose of something, it goes into the blood stream and that's when the immune system becomes alerted. The patch feeds directly into the immune system. Because it doesn't go into the blood system, it's not spotted as an allergen. That's why it's safe – you won't get an anaphylaxic reaction from the peanut patch feed of [peanut] protein.
How effective is the patch?
It's in a double-blind placebo study, and the results aren't out yet. But [study participant] Jessica Strachan [in Toronto] is now able to eat small amounts of peanut – I think she was on the patch for at least a year – whereas she couldn't at the beginning of the study, so it's looking very promising. I haven't come across anyone who suggests that it won't be a possible solution to this problem of severe food allergy.
Would allergy sufferers have to wear the patch for the rest of their lives?
That's a good question – I don't think the research is at that stage yet.
This interview has been condensed and edited.