House Dust Mite Allergens in Saudi Arabia: Regional Variations and Immune Response

Abstract

In order to assess the causative extrinsic allergic factor(s) in school-age children diagnosed as having bronchial asthma and allergic rhinitis, and to qualitatively and quantitatively evaluate the presence of house dust mites (HDMs) in the homes of these children in Saudi Arabia, a study analyzing mite contents in 165 samples collected from patients' indoor environment was conducted. The dust samples were collected from four regions of Saudi Arabia, showing variation in their geography and climate. Immunochemical assays were performed using ALK reagents by ELISA technique. A total of 462 children were also tested using skin prick test (SPT) method for IgEmediated reactions to HDMs. The samples from the Central dry region revealed a very low amount of the potent house dust mites (Dermatophagoides pteronyssinus and D. farinae, the two dominant species in various parts of the world). The samples from the Southern mountainous region contained a very high concentration of Der p I (84,000 ng/g of dust), while the Western coastal region showed a high concentration of Der ƒ I (up to 22,000 ng/g). The mid-Western agricultural region did not exhibit any significant level of either Der p I or Der f I. The maximum level of D. pteronyssinus detected in the Central dry region was 106 ng/g of dust. The data exhibit both qualitative and quantitative variations of HDMs in the three regions and may be attributed to variation in geography and climate, particularly humidity of the regions, which vary significantly. Riyadh in the Central region is considered to have low humidity (<40%), while humidity in the Western coastal region, Jeddah, and the Southern region of Abha is comparatively higher, which helps house dust mites thrive. SPT results in these regions with house dust mite allergens (in addition to other common inhalant allergens) also revealed a considerable number of IgE-mediated reactions, consistent with the frequency of house dust mites in the region. Though more data are being accumulated on the subject to conduct a statistical comparison and more skin tests are underway in the Southern region, the study suggests the presence of at least two HDMs as well as qualitative diversity and quantitative variation of house dust mites in Saudi Arabia. The study also indicates, with a considerable number of IgE-mediated reactions, the possible influence of mites in the allergic manifestations of many patients, which is not only common, but increasing in parts of the country. Ann Saudi Med 1997; 17(2):156-160. The species of house dust mites (HDMs), Dermatophagoides pteronyssinus and D. farinae, as well as other animal-origin allergens such as airborne pollen, fungal spores, cat dander and saliva, and cockroach fecal particles, have been implicated as a cause of respiratory allergies in humans. Both species of mites are known to be prevalent indoors and are considered to be potent allergens in many parts of the world, especially in humid climates.The role of mites (family Pyroglyphidae) as an important source of house dust allerg...

The fauna and distribution of house dust mites in residential homes of Bandar Abbas District, Southern Iran

“…Another study aimed to assess the extrinsic allergic factor(s) in school children with bronchial asthma and allergic rhinitis, and to evaluate the presence of HDM in the homes of these children in Saudi Arabia, mite contents of 165 indoor samples were studied. Skin prick tests in regions with HDM allergens revealed a considerable number of IgEmediated reactions, consistent with HDM frequency (Al-Frayh et al 1997).…”

Skin Test Reactivity to Indoor Allergens Correlates with Asthma Severity in Jeddah, Saudi Arabia

“…Alferah and colleagues conducted a study to analyze HDM content in samples collected from asthmatic patients' indoor environments in four regions of Saudi Arabia [15]. The humid western region showed a high concentration of HDM (particularly more Der f I).…”

“…The principal HDM species are the pyroglyphid mites ( Dermatophagoides pteronyssinus [ Dp ], Dermatophagoides farinae [ Df ], and others), which usually account for 90% of mite species in house dust in temperate regions [9,14]. According to some local studies, similar allergens have been isolated from the homes of asthmatic persons living in different regions of Saudi Arabia [15]. …”

The Saudi Initiative for asthma

“…[109110] Most of the interventions to reduce exposure to these triggers, are helpful, but likely alone, will not help to achieve asthma control. The most important indoor air pollutant is related to tobacco exposure.…”