Materials and Methods
Study area: Boyer-Ahmad County, with over 300,000 population, is located in Kohgiluyeh and Boyer-Ahmad Province in southwestern Iran. The geographical coordinates of this region are between 30◦ 40’ 5.66” N and 51◦ 35’ 16.66” E. The high average annual rainfall in Boyer-Ahmad County (almost 354 mm) has made this area one of Iran’s most important hubs of agriculture and animal husbandry (8).
Patients and Sampling: This case-control study was conducted in Boyer-Ahmad County in southwest Iran between June to October 2021. Two hundred allergic asthma children (aged 1-15 years) admitted to Emam Sajjad Hospital in Boyer-Ahmad County, having at least one allergic asthma manifestation, whom a pediatrist diagnosed according to the International Study of Asthma and Allergies in Childhood (ISAAC) criteria (9). The diagnosis of asthma was made if all the following criteria were met: (I) Recurrent episodes of one or more of the following symptoms : wheezing, cough, breathing difficulties, and chest tightness, particularly at night or in the early hours of the morning; (II) Respiratory symptoms improve spontaneously or after treatment (bronchodilators associated or not with corticosteroids); (III) Presence of triggers or aggravating factors such as exposure to allergens or irritants, physical exercise, weather changes or emotional stress. Individuals with a genetic predisposition to allergic asthma were excluded.
Furthermore, 208 children were enrolled as healthy subjects with non-allergic conditions based on the abovementioned criteria. Control subjects were individually matched regarding age, sex, and residence. Five mL of fresh blood was taken from each individual, and the sera were separated and stored at -20°C until serological tests were performed. The informed consent form, along with a structured questionnaire containing sociodemographic information and related risk factors for toxocariasis such as close contact with dog or cat, \RL pica disorder, consumption of unwashed vegetables or contaminated water, allergic asthma risk factors including parental asthma, as well as the contact with soil was questioned and filled up by parents of participants.