Allergic diseases such as bronchial asthma and allergic rhinitis have increased in the pediatric and adults populations in Saudi Arabia. Apart from traditional lifestyle, the hot temperatures force families to spend more time indoors, resulting in high probability of individuals' exposure with the indoor allergy sensitizers. In order to evaluate their impact in the allergic population, a nationwide study of various allergy and asthma sensitizers was conducted simultaneously in several cities of Saudi Arabia including coastal and non-coastal regions, during 2015-2016. A total of 560 house dust samples (HDS) from 164 allergic patients and 396 control homes were collected in sterile ziploc bags, by vacuuming from seven regions. Samples were sieved, extracted in PBS-Ph8 and analyzed by ELISA using seven different antibodies from Indoor Biotechnologies (Cardiff-UK). The targeted allergens included Dermatophagoides pteronyssinus (Der p1), Dermatophagoides farinae (Der f1), Blattella germanica (Bla g1, Bla g2), Felis domesticus (Fel d1), Rattus norvegicus (Rat n1) and Blomia tropicalis (Blo t5). Chi-square test and odd ratio to test the association between patients and controls as well as detection rate in coastal and non-coastal cities were conducted. The analyses of data between patients and controls as well as coastal verses non-coastal regions revealed quantitative variations in their threshold values. Der p1, Der f1 and Blo t5, the three house dust mites (HDM) antigens were higher in the coastal regions compared to non-coastal. While the other allergens viz. Bla g1, Bla g2, Fel d1 and Rat n1, exhibit an opposite trend. Significant levels for Bla g1 in Makkah (p < 0.0001) and Riyadh (p < 0.0006), Rat n1 (p < 0.0001) and Blo t5 (p < 0.0038) for Riyadh were obtained. The results are expected to help physicians, allergists and hospitals in selection of appropriate diagnostic test panels and may further help in therapeutic and preventive approaches on a regional basis.

The fungal flora contains diverse organisms including a large number of fungi, molds, mushrooms, yeasts, rusts, and smuts etc. Airborne fungi are important source of indoor allergens and studies confirm their role in the development of allergic diseases. In order to identify indoor fungal allergens, 539 house dust samples were collected from different regions in Saudi Arabia. Samples were analyzed by culture employing Sabouraud Dextrose and Potato Dextrose Agar. The cultivated plates were incubated at 25°C up to 5 days. Colony forming units (CFU) were enumerated and identified.Various fungal species were identified from the samples. The majority of fungi identified belonged to the allergenic genera. Aspergill us niger constituted 38.5%, A. fumigat us 15.5%, Rhizopus spp 14.5%, Penicillium spp 8%, Aspergill us spp 7.1%, Alternaria spp 4.4%, Yeast 4%, Mucor 3%, Cladosporium spp 2%, Fusarium spp. 1%, and other minor type include A. flavus 2%. The noncoastal cities (n=455) showed a higher percentages than coastal cities (n=84) because of difference in sample collection.Public places, primarily mosque, was included in the study. Out of 104 samples, Aspergill us niger constituted 39%, Rhizopusspp 14%, Aspergill us fumigat us 12%, Alternaria spp 10%, Fusarium sp. 8%, Penicillium spp 6%, As pergill us spp 6%, Ulocladium, Bipolaris and Yeast 2%, Mucor, Cladosporium spp and Drecslera spp. 1%.Exposure to certain fungal species cause sensitization and allergic reactions and may increase severity of asthma symptoms. Therefore, proper avoidance strategy need to be adopted with a regular cleaning of storage area and humidity control measures, if possible.