Asthma, Airway Symptoms and Rhinitis in Office Workers in Malaysia: Associations with House Dust Mite (HDM) Allergy, Cat Allergy and Levels of House Dust Mite Allergens in Office Dust.

Fang Lee Lim,Leslie Thian Lung Than,Jamal Hisham Hashim,Dan Norbäck,Zailina Hashim,Salmiah Md Said,Maosheng Yao

doi:10.1371/journal.pone.0124905

Abstract

A prevalence study was conducted among office workers in Malaysia (N= 695). The aim of this study was to examine associations between asthma, airway symptoms, rhinitis and house dust mites (HDM) and cat allergy and HDM levels in office dust. Medical data was collected by a questionnaire. Skin prick tests were performed for HDM allergens (Dermatophagoides pteronyssinus, Dermatophagoides farinae) and cat allergen Felis domesticus. Indoor temperature and relative air humidity (RH) were measured in the offices and vacuumed dust samples were analyzed for HDM allergens. The prevalence of D. pteronyssinus, D. farinae and cat allergy were 50.3%, 49.0% and 25.5% respectively. Totally 9.6% had doctor-diagnosed asthma, 15.5% had current wheeze and 53.0% had current rhinitis. The Der p 1 (from D. pteronyssinus) and Der f 1 (from D. farinae) allergens levels in dust were 556 ng/g and 658 ng/g respectively. Statistical analysis was conducted by multilevel logistic regression, adjusting for age, gender, current smoking, HDM or cat allergy, home dampness and recent indoor painting at home. Office workers with HDM allergy had more wheeze (p= 0.035), any airway symptoms (p= 0.032), doctor-diagnosed asthma (p= 0.005), current asthma (p= 0.007), current rhinitis (p= 0.021) and rhinoconjuctivitis (p< 0.001). Cat allergy was associated with wheeze (p= 0.021), wheeze when not having a cold (p= 0.033), any airway symptoms (p= 0.034), doctor-diagnosed asthma (p= 0.010), current asthma (p= 0.020) and nasal allergy medication (p= 0.042). Der f 1 level in dust was associated with daytime breathlessness (p= 0.033) especially among those with HDM allergy. Der f 1 levels were correlated with indoor temperature (p< 0.001) and inversely correlated with RH (p< 0.001). In conclusion, HDM and cat allergies were common and independently associated with asthma, airway symptoms and rhinitis. Der f 1 allergen can be a risk factor for daytime breathlessness.

Highlights

Malaysia is a tropical country with warm and humid climate throughout the year
One Malaysian study showed that Blomia tropicalis (8,934 mites/g), Dermatophagoides pteronyssinus (4,553 mites/g) and Malayoglyphus intermedius (1,020 mites/g) were three most common in home dust [2], while in Malaysian schools, levels of house dust mites (HDM) (Der p 1 and Der f 1) and Blomia tropicalis (Blo t) allergens in school dust were low [3]
We examined the correlations between HDM allergens levels and indoor environmental variables

Summary

Introduction

Malaysia is a tropical country with warm and humid climate throughout the year. Continuous warm and humid environment will facilitate the growth and proliferation of both house dust mites (HDM) and storage mites. The mites have the ability to build up large populations as they can complete at least 12 life cycles per year [1]. Clinical studies in patients demonstrated that allergy to HDM and cat allergens were the most common allergies in Malaysia [4,5,6,7]. We found no previous population based epidemiological study from Malaysia investigating associations between HDM allergens in office dust and the prevalence of asthma, airway symptoms and rhinitis in office workers

Objectives

Methods

Findings

Conclusion