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Seasonal allergies seem to be on the rise

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Published: 14 May 2004

MUHC experts offer information and advice

MUHC experts offer information and advice

A runny nose, sneezing and congestion may seem like a spring cold, but is it? It’s allergy season again—that time of the year when Montreal’s alder, birch and oak trees unleash a noxious dust that transforms many people into drippy-nosed, itchy, coughing and congested zombies.

More than five million Canadians show symptoms of hay fever at some point during the year. In Montreal, trees pollinate from mid-April to early June, followed by grasses in June, and ragweed between mid-August and the first frost. "Some people are allergic to them all, others just one," says Bruce Mazer, a pediatric allergist at the Montreal Children’s Hospital of the McGill University Health Centre (MUHC).

Allergies, including hay fever, are orchestrated by the body’s immune system, which identifies and reacts to different allergens. When an allergen, such as ragweed or tree pollen, enters the body of someone predisposed to allergies, it triggers an immune reaction and the production of allergen-specific antibodies called IgE. These antibodies then migrate to mast cells lining the nose, eyes and lungs. The next time a pollen particle drifts into the nose, mast cells release a slew of chemicals that irritate and inflame the moist membranes lining the nose (allergic rhinitis) and produce the symptoms of an allergic reaction.

Seasonal allergies seem to be on the rise, and many experts suspect that our cleaner lifestyle is to blame. Antibacterial soaps crowd the kitchen sink and antibiotics more readily available than twenty years ago. Without regular priming, the theory goes, the immune system gets bored and overreacts to pollens, or other allergens.

Genetics also plays a role in developing allergies. Children born to parents with allergies are more likely to suffer from allergies. Tom Hudson, the head of McGill University’s Genome Quebec Innovation Centre, is one of many researchers trying to determine which genes influence allergies.

Children commonly come down with their first bout of allergic rhinitis around four years of age, and many may also get hives. "It’s an important disease because these kids are miserable," says Mazer. "They can’t function, they’re often tired, and they’re on medication." Children’s symptoms generally become more aggravated until adolescence, at which point they can either improve or worsen some more.

Dr. Joseph Shuster, a MUHC immunologist, says about 5,000 adult patients visit the allergy clinic at the Montreal General Hospital annually. Of that, about one-third come in with seasonal allergy complaints. "They are often the parents of children with allergies," he says. "It’s a familial illness."

Allergies can’t be prevented, but they usually can be controlled. Identifying and avoiding the allergen is the best way to keep symptoms at bay. Pollen’s ubiquity does make it hard to dodge, but small lifestyle changes can often make a big difference. Mazer recommends allergic individuals keep their windows and doors shut in both your house and car, especially in the evening, when ragweed and most trees tend to release their pollens. If the symptoms persist, immunotherapy or medication is the next step.

Regular allergy shots (immunotherapy) can help allergic individuals build up a tolerance to particular allergens. The doctor injects a small amount of the allergen, increasing the dose over three to five years, reducing symptoms for many patients. But it isn’t a perfect solution for everyone: regular shots don’t fit the schedules of people who travel frequently and children don’t like injections. "Thirty to forty percent get fantastic results," says Shuster. But immunotherapy has little to no benefit in another thirty percent.

Over-the-counter and prescription medications can also control the symptoms and antihistamines can calm many symptoms, but many cause drowsiness. "The things that work best are those that you can put in the organ that is bothering you," says Mazer. Nasal sprays are available by prescription and can manage allergy symptoms without drowsiness.

Many people with allergic rhinitis also develop asthma, and have trouble breathing. According to the American Academy of Allergy Asthma and Immunology the incidence of asthma among people with allergic rhinitis may be as high as 38 percent. And a recent study showed that there were more asthma hospitalizations in Canada as airborne pollen and spore counts rose.

"Montreal is a bad place for hay fever," says Mazer. "We get big peaks because everything blooms at the same time. It’s a short but intense misery."

Allergy Symptoms

  • sneezing
  • stuffy or runny nose
  • itchy nose, throat or ear canals
  • ear congestion
  • itchy, watery eyes
  • shortness of breath
  • coughing or wheezing

Preventing hay fever

  • know what you are allergic to and try to avoid it
  • keep windows closed, use air conditioning instead
  • clean filters on heating and air ducts regularly
  • choose your outdoor activity time carefully
  • start treatment early
  • choose the right treatment: antihistamines work for itch and swelling, but not on nasal blockage, and they can cause drowsiness

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