Understanding Allergies, What Is An Allergic Reaction?
Allergy – A Sensitive Mistake
The immune system starts overreacting to environmental things that are normally harmless. The result: things that pose no threat of disease – such as mould, weeds, food, grasses, feathers, dust mites, pollen grains or flakes of dog or cat skin – become fearsome enemies that throw the immune system into high gear.
Although rarely fatal, allergies are chronic and costly. Experts estimate that workdays lost by people who must stay at home to nurse their misery cost Australia and New Zealand together more than $1000 million annually.
Many more allergy sufferers, including children, manage to go to school or work, but they may underperform at daily task because their symptoms or medications make it so difficult for them to stay alert and concentrate.
When do Allergies Occur?
Allergies are tricky. In a susceptible person, the first exposure to a particular allergy-causing substance, or allergen, may set the stage for a lifetime of annoyance. But not always, so allergies can develop at any age.
What’s more, the first time an allergen triggers an immune reaction, no symptoms appear.
Instead, the body becomes sensitized to the allergen, so the white blood cells manufacture antibodies against it. This causes the immune cells to sense the allergen’s presence if it returns days, even years, later.
The immune system then responds with overkill. A cascade of irritating chemicals is released and any or all of the familiar allergy symptoms appear – sneezes, coughs, hives or wheezing.
In rare cases, the reaction leads to anaphylactic shock, a life-threatening attack characterized by the swelling of body tissues, including the throat, and a sudden fall in blood pressure.
People who know that they are at risk of suffering anaphylactic shock, which goes hand-in-hand with allergies to insect stings, certain medications and foods, should carry kits that include adrenalin to counteract these serious symptoms.
Are allergies Inherited?
So are allergies inherited? Very often, the answer is ‘Yes’. If either parent has allergies, your chances of being affected are much greater. But an inherited tendency, called atopy, is rarely the whole story.
A lot depends on which allergens you encounter in life and on other factors, such as the age at which you are exposed to an allergen.
It’s possible for a person to come from a long line of allergy-prone ancestors and remain allergy-free for ever. Or the reverse can happen: for example, no one in your family has ever sneezed in response to a cat, but the moment you step into a cat owner’s home, you can’t stop achooing.
One thing is clear: allergies are on the rise.
The number of diagnosed cases of asthma, a very common and potentially serious allergic disorder, is more than 2 million in Australia and 500,000 in New Zealand and the numbers are doubling every 15 years.
One factor in the increase is the widespread construction of tightly sealed, energy-efficient homes, in which allergens such at house dust mites and other irritants may activate full-blown allergic responses that might otherwise have been avoided.
If your office is similarly sealed and perhaps air-conditioned, it may provoke a similar reaction.
Psychological factors may contribute to allergies, too. The emotions caused by stress have long been thought to trigger allergic attacks or to make symptoms worse.
Also, someone who is anticipating an allergic reaction to a particular substance will, quite often, have the expected reaction – even when the substance is a fake. For example, hypnotized subjects sometimes develop a rash to ordinary ivy after being told that it is poison ivy.
Uncertain of Allergy
Some people who think they have allergies are sensitive to such substances as cigarette smoke and paint fumes, which can cause lookalike symptoms. Even stepping into cold air can trigger wheezing.
Respiratory symptoms may be due to a chronic cold, rather than allergies. Always see a doctor if your symptoms are long lasting or severe.
The Path of an Allergic Reaction
Allergens – pollen grains, for example – enter the body through the eyes, nose or mouth. The grains land on mucous membranes where they are detected by T-cells and identified mistakenly, as being harmful.
Excited T-cells signal B-cells to produce IgE antibodies, which then latch onto the pollen and tag it as foreign.
The IgE antibodies bind strongly to certain cells in the skin and airways. Now primed for the next exposure to the same type of pollen, these cells will quickly release histamine and other inflammatory chemicals.
Tissues swell. The nose becomes clogged, the palate itchy. Eyes turn watery and red. Sneezing may ensue. These classic symptoms ranging from mild to severe, will reappear with every future encounter with similar pollen grains.
If allergy symptoms are severe and A allergen has been identified, immunotherapy may be an option in some cases. In this treatment (also referred to as allergy shots or desensitization), you will first be thoroughly investigated by an allergy specialist.
Then you will be given injections of small amounts of the substance to which you are allergic.