Introduction
Allergy, one of the most common types of hypersensitivity diseases,
typically includes asthma, hay fever, atopic eczema and food allergies
and may cause symptoms such as eye redness, sneezing, runny nose and
even death. In recent decades, the incidence of allergic diseases has
increased annually worldwide 1-3. For example, the
estimated rates of food allergies increased from 3.5% to 6% in the
United Sates 4. The prevalence of asthma in American
adults increased from 7.21% in 2000 to 8.52% in 2009, and one study
speculated an increase in the number of patients aged older than 14
years with asthma in mainland China 5. In addition to
affecting the quality of life, a significant economic burden of these
diseases was transferred to society and the national health care system4. Allergy is caused by exaggerated immune sensitivity
to certain environmental substances (called allergens), which are
usually food, plants, animals, insects and so on. Therefore, the study
of the prevalence of sensitization to allergens is key for preventing
and treating allergic diseases.
Many studies have focused on the prevalence of allergens and found an
increase in the prevalence of allergies. The increase was found to be
associated with economic improvement, lifestyle, climate change, and
geographical and seasonal variations 6, 7. China is a
large country with a rapidly developing economy, wide geography, and a
diverse climate and diverse lifestyles. Although a series of studies
have explored the prevalence of allergen sensitization in China, the
majority of them focus on one part of geography in China8, 9. In 2009, a study was conducted to estimate the
prevalence of 13 common aeroallergens among patients with allergic
asthma and/or rhinitis in mainland China 6. Although
the study investigated the differences in the prevalence and pattern of
allergen sensitizations in four regions of China, it only paid attention
to aeroallergens and did not consider food allergens. In this study, the
skin prick test (SPT) was used to detect the sensitization to allergens.
The method has low accuracy for positive results because it is heavily
affected by certain factors, such as the skill of the tester, reagent
used, interpretation of results and so on 10.
Furthermore, dividing China into only four regions may neglect detailed
information about the characteristics of sensitization prevalence in
different places in China. Therefore, our research has the following
different characteristics compared with previous studies: 1) covering a
variety of allergic diseases, 2) exploring both aeroallergens and food
allergens simultaneously, 3) including a large set of data from seven
regions of mainland China, and 4) using an internationally recognized
method of sIgE testing, ImmunoCAP, to detect sensitization. The above
advantages may help us obtain more accurate and reliable results and
conclusions.
In this paper, we explored the prevalence and patterns of sensitization
to the four most common food allergens and five aeroallergens among
patients with allergic symptoms in all the seven geographic regions of
mainland China. The influences of seasonal and age variations on
prevalence were also investigated. Furthermore, we specifically explored
the factors that influenced these variations. Allergen sensitization
patterns in different population demographics may contribute to
improving the diagnosis and prevention of allergic diseases and then
reducing economic losses.