Impact of allergy on health
Angel Mazon. MD PhD.
EAACI Website Co-editor
Mary is a 32-year-old woman who always had a good health condition. In the last three years, since she moved from her flat in the city to a house in the country, she has started to have rhinitis symptoms, with sneezing, nasal congestion and itching, and red and watery eyes. From time to time she had a pill of antihistamine, which relieved her symptoms. Last Spring, in a warm but windy day, she was having a walk in the open air with some friends when she started coughing, with a feeling of difficult breathing and “whistling” in her chest. She had to be transferred to the emergency department of the nearest hospital, where she was admitted for 48 hours with an asthma attack.
This situation is not uncommon. Allergic asthma is a condition that can appear at any age. Allergies do not just appear during childhood. Anyone can obtain allergies at an older age, and to usual things that has been previously tolerated. Allergens are the substances that are able to induce allergy. These can be environmental, such as pollens, mites in house dust, mould spores, or dander from pets or other animals. Any food can act as an allergen; the most common ones are cow’s milk and egg during infancy, and seafood or nuts for adults. Someone who has been eating, for example, shrimps since childhood can one day start developing a food allergy and having allergic reactions when eating or even touching or smelling them.
Allergy is a systemic disorder, meaning that it affects the whole body. The manifestations appear mostly in organs exposed to the environment with the symptoms mainly appearing in the respiratory system, causing asthma, rhinitis and conjunctivitis, in the skin, causing eczema or urticaria, and in the digestive system, causing vomits, diarrhoea and abdominal pain. An allergic person can have symptoms in only one organ, or, more commonly, in two or more organs at the same time.
Allergy affects nearly one in four people in developed countries, and is considered one of the epidemics of the 21st century. Allergy was not frequent hundred years ago, but has been steadily rising during the last 25-30 years. There are predictions that if might affect half of the population in 25-30 years more. Although there are some reports that this growth may have stopped in some areas, it has yet to be confirmed. The regions with the highest figures for allergy are Oceania and North America, followed by Latin America. The European, African and Asia-Pacific countries show intermediate figures, and the lowest ones can be found in the Indian sub-continent.
Some people have an inherited predisposition to develop allergies which is called atopy. They tend to become allergic at an early age, and to many allergens, one after the other. There are, however, other people who have no family history of allergy, who become allergic in adulthood, and to only one or to a limited number of allergens, just like Mary. The reasons for the increase of allergy are not fully known. As genetic changes cannot account for such an increase, the reasons must be environmental. Exposure to allergens, molecular changes in these, pollution, the effect of food and nutrients, the type and amount of microbial flora in the human body, and the life style and hygiene are among the factors that are being investigated. Also, the interactions among these factors and with our genes seem to play an important role. In the next few years findings are expected that will help us understand, treat and prevent allergy.