Hygiene Hypothesis and Occupational Asthma to Vegetable Textile Dusts: A Pilot Study

Background: Over the last decades, the prevalence of allergic manifestations has increased significantly. To explain the increase in the prevalence of asthma, Strachan advanced the Hygiene Hypothesis, which states that decreased exposure to infectious microorganisms in infancy may have contributed to changes in the maturation of the immune system during childhood. To the best of our knowledge, no analytical studies detailing the links between the Hygiene Hypothesis and occupational allergy have been carried out to date. Objective: To study the relations between the factors involved in the Hygiene Hypothesis and the occurrence of occupational asthma (OA) to vegetable textile dusts. Methods: A case-control study was conducted from September 2017 to September 2018. The cases and controls were enrolled from the occupational medicine department of the University Hospital "Farhat Hached" of Sousse (Tunisia) among patients attending from 2009 to 2016. The case group was composed of patients diagnosed with OA to vegetable textile dusts. Controls were age and gender matched, working in the textile sector and not suffering from any allergic diseases. Results: A total of 57 OA cases and 112 controls were enrolled. Four factors involved in the Hygiene Hypothesis were independently associated with OA to vegetable textile dusts: the lowest rank in siblings (p=0.037; ORa=0.14; 95% CI= [0.02-0.90]); contact with animals (p =0.006; ORa=0.22; 95% CI= [0.08-0.65]) especially cats; history of parasitic and/or mycotic infections in childhood (p=0.004; ORa=0.035; 95% CI= [0.004-0.35]) and history of viral infections in childhood (p<10(-3); ORa=0.028; 95% CI= [0.01-0.14]). Other factors had a protective effect, such as the parents' low socioeconomic level and the father's occupation as a farmer. Conclusion: The microorganism-rich environment during childhood is an important model for understanding the mechanisms involved in the development of allergic asthma. Our data suggest that prevention of OA in adults might require early intervention in childhood.