Allergy - 21 century disease
Allergy is certainly not uncommon. From its various forms suffers from a third man, and in the past 20 years, the number of allergies is growing especially rapidly.
The international study (ISAAC) showed that the frequency of occurrence of allergic rhinitis is 20-25% of the population, and in the past 25 years, it has tripled.
The increase of allergic diseases, around the world, is explained by factors external environment, and change behaviors and habits. This explains why the frequency of allergy varies in different countries and even in different cities.