It's that time of year again, when along with warmer weather, millions of Canadians are welcoming the sniffling, sneezing and itchiness of seasonal allergies.
The number of people who suffer from these airborne allergies, a condition known as rhinitis, has been on the rise in recent decades, especially in northern areas like Canada, where pollen is sticking around for longer than usual.
"The spring pollen seems to be earlier than it was 15, 20 years ago," says Estelle Levetin, an aerobiologist at the University of Tulsa. She also notes that one study, which included data from Canada, showed the ragweed season in the fall was lasting longer, too.
Fortunately, for allergy sufferers across the country, there is hope.
For those who suffer from grass and ragweed allergies, sublingual immunotherapy, which exposes the body slowly to small doses of an allergen before and during allergy season, is a new treatment option.
So are — still pricey — injections of antibodies that block the communication pathways that bring on inflammation.
And researchers at McGill University in Montreal are working on a vaccine, which shows promise with mice and may teach the body to respond to a variety of foreign substances without raising an allergic reaction.
How allergies work
Nobody really knows why people develop allergies while others don't — although there are some interesting theories floating around. But scientists do know what's happening inside the body once the allergy starts.
An allergic response is caused by what's called an allergen — for people with seasonal allergies, that would be be pollen (specifically, the proteins in them) from trees, grasses and weeds.
When that pollen makes it into the nose of an allergic person, their immune system mistakes it for a harmful foreign invader and goes into overdrive.
It releases antibodies to attack the allergen, which prompts cells in the person's nose, throat and lungs to release chemicals such as histamine, which is what leads to that sniffling and sneezing, or in more severe cases, asthma attacks.
There is no cure for seasonal allergies, so treatments have typically focused on managing the symptoms or avoiding allergens in the first place.
"We're still recommending things like keeping the window closed, keeping the furnace clean, keeping car windows closed, and not smoking in the home, because that aggravates allergies," says Paul Keith, an investigator at AllerGen, a network of Canadian allergy experts, and an associate professor at McMaster University in Hamilton.
Other advice: Use a dehumidifier, wash your linens often, and change your clothes as soon as you get home.
For medicinal treatments, the two usual standbys are antihistamines, such as Benadryl or Allegra, along with steroid nasal sprays like Flonase or Nasacort.
A new nasal spray, Dymista, contains both antihistamines and steroids, and became available in Canada just last year.
For those who suffer from grass and ragweed allergies, tablets containing small doses of the allergen are dissolved under the tongue either daily or a few times a week for a period before and during allergy season. It's based on the idea that by exposing the immune system to small doses of the allergen, you can make your cells more tolerant to it.
"This is a whole new type of desensitization which works in principle the same as allergy shots. But they are easier to take, probably safer, and it's done at home" instead of the doctor's office, says Dr. Susan Waserman, an allergist and professor at McMaster University.
"It makes it quite easy for children and people who don't like needles to desensitize themselves."
Some studies also suggest that after about three years of daily treatment, sublingual immunotherapy provides a long-lasting effect for many people, basically reprogramming the body to be more tolerant of the allergen.
Although the only tablets currently available are for grass and ragweed pollen, Wasserman says that there are others on the way for people with tree or dust mite allergies.
Unfortunately, this kind of treatment has little or no effect on at least a third of allergy sufferers, with only about 40 to 60 per cent getting good results.
Another type of treatment, specifically for people with severe asthma, blocks the communication pathways in an allergic response. A patient would receive a shot of antibodies that target the "communication molecules" that lead to inflammation.
"But it's an injection so it's a big deal," says Christine McCusker, an associate professor of pediatrics in the Meakins-Christie Laboratories at McGill University.
Omalizumab, known by the brand name Xolair, requires an injection every two to four weeks — at roughly $750 for a 150 mg dose, it could cost up to almost $20,000 a year.
That cost may be reasonable for people with severe allergies or asthma, but probably doesn't make sense for the casual allergy sufferer, McCusker says.
Other antibody treatments that work the same way, but target different molecules, are currently being reviewed by Health Canada and could be on the market by later this year, says Paul Keith.
New research out of McGill University in Montreal is showing some early promise for a potential allergy vaccine. The treatment works by essentially teaching the immune system how to respond to allergens in a normal way.
Using a nasal spray, researchers administered a molecule to newborn mice who hadn't yet developed any allergies. When they exposed the mice to these allergens later on, the molecule stopped an allergic response from being triggered.
"So basically what you've done is — despite the genetics and despite all the things you can try and do to drive an immune response — that once the immune system has learned that the pollen is just a pollen you don't need to create a big inflammatory response," says Christine McCusker, who led the study.
Unlike other immunotherapies that only work on specific allergens, the molecule would be effective for all of them — so it wouldn't matter if you're allergic to pollen, dust, cats or dogs.
Previous studies also showed that researchers could use the molecule to reprogram the immune systems of mice who were already allergic to pollen, a finding that could eventually pave the way towards finding a cure.
The treatment is still in animal testing phase and has a long way to go before it even reaches human clinical trials, but McCusker is hopeful. She says that with the right funding and if everything goes smoothly, the nasal spray could hit the market in five to 10 years.
"It's a huge potential management for allergies," she says. "It's just one spray [every month], and your allergic symptoms are stopped."