Background:In order to investigate the role of airborne Alternaria spp. in the sensitization of individuals having respiratory allergy symptoms, particularly bronchial asthma, an aerobiologic and clinical (diagnostic) study was conducted at several centers in Saudi Arabia. Materials and Methods: Airborne Alternaria spores were studied at four different centers in Riyadh, Jeddah and Al-Khobar, including three years at one site. Skin prick tests (SPT) were conducted on a total of 616 allergic individuals attending allergy clinics at six different hospitals in Abha, Qassim, Gizan, Jeddah, Hofuf and Makkah regions. Results: Alternaria spores constituted between 1.9%-9.6% of the total fungal air spora, and the maximum concentration exceeded 5x10 2 spores per m 3 of air in Jeddah, followed by 4.9x10 2 spores per m 3 in Al-Khobar. Mean weekly and monthly concentration of Alternaria fluctuated, reaching up to 150 spores per m 3 and 60 spores per m 3 , respectively. Quantitative regional variations were also recorded. IgE-mediated SPT reactivities conducted on allergic patients resulted in an overall 21.6% positive reactions, showing mild, moderate and strong wheal and erythema. Conclusion:The findings reveal that Alternaria spores are prevalent as a major component in the outdoor environment of the Kingdom, with peaks in April and October. The overall 21.6% positive SPT reactions indicate the sensitization level or cross-reactive sensitivity to Alternaria allergens. The study suggests that airborne Alternaria can be a potential allergic sensitizer in susceptible individuals and can be a risk factor in sensitized individuals with symptoms of bronchial asthma and allergic rhinitis in the Kingdom of Saudi Arabia.

An allergological study to evaluate allergenicity to Cladosporium, Burkard 7-Day Volumetric Spore Trap and Personal Volumetric air sampler (viable mode) were employed to conduct air sampling for 12 months in three regions of Saudi Arabia. The study was extended for a continuous 3rd year at one site. Skin prick testing (SPT) was also conducted on 605 allergic individuals using commercial extracts of C. herbarum. Cladosporium emerged to be the most prevalent genus in the outdoor environment constituting up to 25% of all fungal spores in the dry region and 37.1 and 41.2% in two coastal cities respectively. Amongst the species C. sphaerospermum, C. macrocarpum, C. cladosporioides and C. herbarum were noted. Maximum hourly concentrations up to 14 x 10(3) m(-3) were recorded in coastal region during winter months. Morning concentrations were higher at both city sites compared to afternoon concentration. SPT result revealed an overall 19.67% positive reactions with majority showing mild reactions.

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...

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A vast majority of studies investigating cytokine profiles in contact dermatitis (CD)