Adrien is back on farmacist.info! Today he is presenting the issue of allergies, an increasing problem in our society today.
What are the causes behind this increase in the numbers of allergic patients, how can we prevent/treat them and what to expect from the future? You will find the answers to these questions in our article.
An allergic reaction
An allergy is an immune reaction of normal body defense. Being “allergic” is being overly reactive to often harmless components. Worldwide, 400 million people suffer from allergic rhinitis, half of which have an asthmatic background. Allergies have been ranked by the WHO* as the fourth most abundant chronic disease worldwide.
Allergies have seen a dramatic increase over time. They reign for the title of “Disease of the 21st century!” In the last 40 years, cases of respiratory allergies have been multiplied by 50 times, while food allergies by 4 times in the last 10 years!
Allergic diseases stem from hereditary as well as acquired factors such as allergens and/or environmental factors. Children whose parents have allergies are almost twice as likely to be allergic. By 2050, with the cumulative effects of environmental decay and taking in consideration genetic mutations, it’s estimated that half of the world population will have developed an allergy.
Fig.1 Pollen – one of the most sensitising allergen
Why are there so many allergies now?
The cause lies in the very early exposures to alergens. Everything begins in utero, when the allergies of the mother during pregnancy sensibilise the unborn child. The frequency and degree of exposures has increased during our life-time for all known allergens (See Table 1). For example, climate change has significantly increased the amount of pollen produced (illustration above in Figure 1), associated with pollen seasons becoming longer. Furthermore, rhinopharyngitis during childhood alter the cells of the respiratory mucosa, promoting the passage of other allergens. Moreover, children are exposed to dietary diversification increasingly early, coupled with poor quality of food. As for adults, additives of all kinds (not always indicated on the label of the food we eat), industrialization, the impact of exotic products, insufficient intake of antioxidants, chemical agriculture and intensive farming are suspected of precipitating food allergies. These two major allergen family – ingested and inhaled allergens – generate increasingly cross-allergic conditions with digestive, skin or general symptoms (such as anaphylactic shock).
In addition, there are aggravating factors. For example, diesel particles are dangerous because they can bind to certain chemical compounds and pollens, increasing the risk of allergy. The ozone particles promote allergies by the same mechanism, because the nasal mucosa absorbs 40% of the inhaled ozone. Pollution, along with humidity promote the development of mites and molds within our over-heated and poorly ventilated buildings. The houses are also saturated with various household products (aerosols, etc.) which cab be allergenic.
In blood, some antibodies (IgE**) are evidence of allergic sensitivity. Chronic pollution promotes IgE production and thus increases the risk of allergic reactions.
Finally, there is an “hygienist aspect”, suggested long ago by the Pasteur Institute : lifestyle in developed countries, including the lack of stimulation of our immune systems by certain bacteria due to a very high hygienic level could explain why immune systems are less competent, less educated, and thus react more to external elements that should not be allergenic.
Table 1. Most common allergen and their sources
Acting early to prevent complications
In Europe, the ECDC*** estimates that patients wait an average of seven years before going to consult for their allergies. This is often too late, claim the allergists (medical doctors), recalling that this disease can worsen in time. Seasonal allergies, that comeback with spring, deserve all our attention at the first signs and should encourage us to act promptly to avoid complications. The challenge is to follow 3 simple steps:
1/ develop treatments to alleviate the symptoms
2/ identify allergic situations and involved allergens
3/ desensitize allergic people.
1/ Treating symptoms
We must act as soon as symptoms occur, such as asthma, rhinitis, conjunctivitis, skin reaction, because these signs alter the quality of life and an early allergic reaction can worsen thereafter and endanger patients.
Antihistamines, used since the 1940s are the reference treatment of allergies. These are preventive drugs which block the receptors of histamine, a protein involved in the abnormal immune response that is allergy. The treatment can be continued for several weeks without habituation effect, that is to say without the risk of reducing their effectiveness. There are very few contraindications but caution is always recommended, especially during pregnancy. Some antihistamines are freely available in pharmacies. Finally, adverse effects (drowsiness, mild weight gain, dry mouth, constipation) are mitigated in the second generation antihistamines, the most widely used at present.
2/ Identify involved allergens
Skin tests will allow to identify which substances you are allergic to. Identifying the allergen (pollen, dust mites, cat dander, peanuts, etc.) is an important step in treating allergies and preventing disease aggravation. Blood tests may also be performed to look for specific IgEs which are forme when the body is exposed to a specific allergen. These tests can treat up to 90% of allergies if the source is identified.
Drug treatments only reduce the symptoms, the cannot cure the patient. Allergen immunotherapy, commonly called desensitization, remains the only lasting targeted therapy to treat allergy. It consists in regularly stimulating your immune system with minute doses of allergen, gradually increasing the doses to induce tolerance. This method shows varying effectiveness depending on the history of the disease and the immune background of the patient. Meanwhile, it’s very difficult to anticipate the degree of response to this technique for each patient.
Following these 3 rules and making sure that you test yourself for possible allergens can slow down disease evolution, but, in the end, there are many other changes that humans need to make in order to stop the increasing percentage of allergic patients. Polution, food, environmental changes and many other factors contribute to the allergic background that so many people cary forward with them and onto the next generations.
Dr. Adrien and the pharmacists,
(*World Health Organization, **Immunoglobulin E, ***ECDC European Centre for Disease Prevention and Control, $in Table 1, cosmetics, MIT : methylisothiazolinone)
Sources: WHO, ECDC, Pasteur Institute, French Association for Allergy and Asthma