What is an allergy?
An allergy is an exaggerated and inadequate response of our immune system against inoffensive substances in the environment. In a normal situation, our body fights these agents that can cause diseases, such as bacteria or parasites and “tolerates” beneficial substances such as food, the air that we breathe or medication.
For those who suffer from allergies, special antibodies are formed (of the IgE type) that incorrectly interpret an inoffensive substance (an allergen) as an aggressor. These antibodies live in our noses, eyes, bronchi, skin and digestive system, causing intense inflammation, giving rise to the typical symptoms of an allergy.
Why do we become allergic?
A genetic, personal or family predisposition to produce these special antibodies against environmental allergens is referred to as “atopy”.
A child with a parent that suffers from allergies for example, has a 40%-60% risk of also being allergic. If both parents are allergic, the possibility increases to 60%-80%. On the other hand, the risk is quite low (about 5%) if there are no allergies in the family.
Allergic diseases involve multiple factors, which means that they are influenced as much by genetics as by environmental factors. Viral respiratory infections and exposure to pollutants, especially to tobacco smoke, appear to be equally important in the appearance of allergies. Additionally, a sedentary lifestyle, obesity and infrequent contact with nature also appears to contribute towards allergies, an epidemic that sprung up at the end of the 20th Century.
Why are we allergic to some substances and not to others?
As a general rule, we are allergic to common substances in our environment. For example, people who live in the Algarve are allergic to the regional pollens and mites, which are different from those found in the north of Portugal and those found in other countries. Each region has its own particularities.
Which allergens are most prevalent in our population, and specifically in the Algarve?
According to a recent study conducted here in the Western Algarve, the most frequently identified respiratory allergy (in 58% of the cases), was to house dust mites, especially a species known as Dermatophagoides pteronyssinus. Mites are small animals that live in the dust of houses, especially in bedrooms. They feed on flakes of shed skin and prefer warm, humid houses. They mainly grow in mattresses, pillows, carpets, sofas and soft toys, but can live anywhere that accumulates dust.
The most important pollens appear to be those of wild grasses (hay) and of olive trees.
Can you give some general advice to people with allergies?
Besides specific treatment for each disease, allergies can improve significantly with environmental control, as long as we know which substances the sufferer is allergic to.
In cases of dust mite allergy, for example, contact occurs in closed spaces, normally at home or at work. Therefore, it is useful to reduce the number of books or toys strewn throughout the bedroom and keep them on shelves or in closed boxes. Also, avoid flannel sheets and covers. Use synthetic rather than feather duvets. All bed linen should be washed at 60ºC , and ideally waterproof anti-dust covers should be used on mattresses and pillows. When cleaning the house, it is better to use a damp cloth so as not to raise the dust. Carpets and rugs can be “home” for large populations of dust mites, so it is best not to have them in your house. Finally, we recommend that you invest in a vacuum cleaner with a HEPA filter (these do not need to be water vacuum cleaners, which are generally much more expensive) and vacuum mattresses and sofas weekly. In the case of pollen allergies, contact normally occurs outdoors, so they are more difficult to avoid if you go outside. Fortunately, in the Algarve the majority of pollens that cause allergies appear only in Spring. I recommend consulting the Boletim Polínico (on Portuguese Allergology and Clinical Immunology: www.spaic.pt) to learn when the pollen levels are highest. On the hottest and windiest spring days, it is perhaps preferable to avoid open-air activities. On these days, sunglasses can protect the eyes from pollens. Lastly, when airing out bedrooms, avoid opening the windows during the day (there are fewer pollens in the atmosphere during the night).