From the Spring 2006 issue of Allergy Today. For more articles like this, subscribe to Allergy Today, click here.

Did you know that the material spread by sneezing can travel 2-3 metres, at a speed of around 150 km/hour? An interesting piece of trivia for most of us, but not for hay fever sufferers. Inga Stünzner reports

Here’s looking achoo

Sneezing may seem like a trivial topic – except to those with allergic rhinitis. Did you know when you sneeze, your nerve impulses travel from your nose to your brain, then back to other nerves that control the muscles of your abdomen, chest, diaphragm, neck, face and eyes as well as the mucous glands and blood vessels in your nose? These muscles work together in the right order to blast out whatever is irritating your nose. That’s a lot of effort, so it’s little wonder those with severe hay fever are left feeling miserable and exhausted.

Trigger happy?

We generally divide triggers into indoor triggers and outdoor triggers. Indoor triggers (house dust mites, cats, dogs and moulds) are typically all-year round but out-door triggers (generally grass, weed and tree pollens) are seasonal .

“Tree season in New Zealand is relatively short compared to Europe, where the birch season in Europe is several months long. Here it is a month or less,” explains Associate Professor Rohan Ameratunga, Allergist and Clinical Immunologist at Auckland Hospital. “So tree allergy here is less of an issue compared with grass allergy, which is an extremely severe problem because its season goes from August/September through to March.”

That makes New Zealand’s pollen season a nine-month nasal marathon! And the bad news is that if you are allergic to one type of grass pollen, you are likely to be allergic to the whole family of grasses because the pollen cross-react. Allergy New Zealand has just released its latest Pollen Calendar, which details specific pollens from trees, grasses and weeds and when to avoid them. For more information, contact Allergy New Zealand.

The reaction

How does something as tiny as pollen cause an allergic reaction? Like any other allergy, allergic rhinitis is an immune system over-response to a protein – such as inhaled pollen or a mould spore. Antibodies are supposed to protect our bodies, but the immune system of a person predisposed to allergy can mistakenly identify a certain protein as an invader and begin to create antibodies against it.

These antibodies, which are called Immunoglobulin E or IgE, attach themselves to mast cells, which are abundant in the nose, eyes, lungs and gastrointestinal tract. When the offending pollen is again encountered, the IgE antibodies grab it, triggering the mast cells to release powerful chemicals, including histamine. This causes the allergic reaction and its symptoms: swelling, redness, itchiness and secretion of mucous.

The burden

Recent estimates have found that 10 per cent to 30 per cent of adults and up to 40 per cent of children have allergic rhinitis. This may be an underestimate, as many patients do not seek medical help for this condition. In the US, it is the sixth most prevalent chronic illness.

It has been labelled by some as an epidemic, as studies have found that in each of the last three decades there has been a 100 per cent increase in its prevalence in developed countries. There have been many theories to explain this increase, including the hygiene hypothesis and environmental factors, but experts are yet to completely explain it.

The overall burden of allergic rhinitis is better understood when one considers that 50 per cent of patients experience symptoms for more than four months per year and that 20 per cent have symptoms for at least nine months per year.

And the actual cost is staggering. Latest US figures estimate about $US1.8 billion a year are spent in direct costs, which include physician visits and medications. About $US3.8 billion per year are spent in indirect costs, which include the result of lost productivity. For children, there are approximately two million lost school days per year due to allergic rhinitis.

Complications

Worryingly, hay fever is often considered a nuisance rather than a major disease and most people will self-treat with natural remedies and over-the-counter medications. Dr Ameratunga cautions that severe hay fever is nothing to be sniffed at.

“If you don’t treat hay fever properly there is usually a significant reduction in the quality of life because people never get a good night’s sleep because they are so congested they can’t breathe through their nose. Or they are constantly gagging and choking because they have a post-nasal drip, which causes their saliva to pool in the back of their throat, ” he explains.

Severe hay fever also predisposes the sufferer to infections because they have difficulty in clearing their mucous, which acts as a good culture medium for viruses and bacteria. If these recurrent infections are not treated, they can lead to surgery.

“I can think of one young woman in Year 13 who was having multiple infections and missing a lot of school as a result. She came in for an evaluation of her infections and it turned out she had undiagnosed hay fever. When the hay fever was fixed, she had a normal quality of life. So it can make a huge difference for some people.”

Infections are predominantly sinus infections, he says, and there is new evidence making a link between salicylate sensitivity — which presumably perpetuates the inflammation in the nose, lungs and sinuses — nasal polyps and asthma. This is called Samter’s Triad.