Exposure to birds and rural areas can protect children from asthma

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According to research published in the journal AllergyFor example, children from rural China had lower rates of asthma and atopic disorders than children from urban Hong Kong, indicating a protective effect of rural lifestyle.

Asthma is one of the most common chronic diseases in childhood, and its prevalence has increased in recent decades. One of the most consistent epidemiological findings is that children living in an agricultural environment are protected from developing asthma and allergies. Based on these data, the purpose of the study was to compare the incidence of asthma and related atopic disorders in children from Conghua and Hong Kong, rural and urban areas in China, respectively, using validated ISAAC Phase III questionnaires. The researchers also aimed to identify environmental factors that may provide protection against the development of asthma in Chinese rural areas.

also read: Having a dog or cat in early childhood is not associated with school-age asthma

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A cross-sectional community-based epidemiological study was conducted. Asthma and allergy symptoms as well as environmental exposures were controlled.

Written ISAAC Phase III questionnaires were distributed to all children aged between 5 and 8 years at the invited day care center / schools and were completed by the parents (or guardians) at home. The questionnaire was developed based on the ISAAC Phase III questionnaire translated into Chinese using a standardized protocol. “Current” symptoms refer to symptoms within the last 12 months; “ever asthma” was defined as having been diagnosed with asthma by a physician in life; other atopic and diagnostic symptoms such as “allergic rhinitis (AR)”, “rhinoconjunctivitis” and “bending eczema” were defined according to previous studies. “Asthma ever” was used as a outcome variable, and its association with various environmental and lifestyle factors was evaluated.


The study involved 14,118 children from Conghua (mean age 6.6 years; 53.5% boys) and 3,145 children from Hong Kong (mean age 6.5 years; 52.6% boys), all aged 5 to 5 years. 8 years.

Survey results showed that the incidence of current wheezing (in the previous 12 months) was significantly lower in rural Conghua than in Hong Kong (1.7% against 7.7%, p <0.001). A lower incidence of asthma was also reported in rural children compared to their urban counterparts (2.5% against 5.3%, p <0.001). In addition, 3.4% of urban children and 0.5% of rural children had sleep-disturbing wheezing (odds ratio [OR] 7.1; P <0.001).

Compared to rural children, urban children also had higher rates of exercise-induced wheezing (10.5% against 6.9%), symptoms of rhinoconjunctivitis (22.2% against 2.7%), bending eczema (8.4% against 4.3%) and use of asthma medication (14.8% against 1.7%) in the previous 12 months (all, P <0.001). Children in urban areas also had higher rates of asthma diagnosis during their lifetime (5.3% against 2.5%), history of wheezing (16.9% vs. 5.8%), allergic rhinitis (39.9% against 8.7%), eczema (28.7% against 21.7%) and use of asthma medication at some point in life (25.5% against 4%) compared to children living in rural areas (all, P <0.001).

The researchers observed that fewer children lived on a farm against children who have never lived on a farm were diagnosed with asthma (2.1% against 3.1%; OR = 0.67; P <0.001). Children living on a farm were also less likely to have used asthma medication (3.7% against 4.6%; OR = 0.81; P = 0.01) and were less likely to have allergic rhinitis (OR = 0.59; P <0.001) compared to those who did not live on a farm. Moreover, compared with children who were never exposed to a farm, even children in the countryside who were only exposed to farms visiting their neighbors had a significantly lower lifetime prevalence of allergic rhinitis (10% against 12.8%; OR = 0.75; P <0.001) and use of asthma medication (4% against. 5.2%; OR = 0.77; P = 0.03).

After adjustment for confounders, exposures to agriculture (odds ratio adjusted [aOR] 0.74, 95% confidence interval [IC 95%] 0.56–0.97) and poultry (0.75, 95% CI 0.59–0.96) were the main factors associated with the protective effect of the disease in rural areas. Further analyzes adjusted for the propensity score indicated that such protection provided by rural life was primarily due to exposure to birds.

The use of foam pillows (aOR = 2.12; 95% CI, 1.14-3.93) and humidity in the home (aOR = 1.58; 95% CI, 1.27-1.98) showed the increased risk of asthma among children in Conghua. Other risk factors for medically diagnosed asthma in this population were synthetic fiber bedding, antiparasitic medication use, and carpet floors.


The study confirms a markedly lower incidence of asthma in Chinese rural children compared to children in Hong Kong cities. According to the researchers, exposure to poultry and agriculture or to unmeasured factors related to them may explain the lower incidence of asthma in children in rural children. For them, the data would complement the results of different rural populations around the world. However, the authors state that further studies are needed to determine the potential biological mechanisms that explain the protection afforded by exposure to birds.


Asthma is a chronic disease that affects millions of patients across the planet. This study opens the door to new avenues for a greater understanding of the disease, which will enable the development of better and more practical strategies for primary prevention and better quality of life.


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