Common Environmental Allergens in the Kingdom of Saudi Arabia and Their Use in the Diagnosis of Allergic Diseases by Skin Test

Much human allergy is caused by a limited number of inhaled small proteins called allergens. Allergens are relatively large and complex molecules, such as pollens, molds, mites and house dust, which are capable of eliciting allergic reactions in susceptible persons. This study was conducted to identify the most common allergens in the kingdom of Saudi Arabia (KSA). Allergens were collected from different areas in the kingdom and used to prepare allergenic extracts to be used as diagnostic kits for diagnosis of allergy by skin prick test. The study included 494 patients diagnosed as truly allergic from five different areas in KSA; Jeddah, Riyadh, Al- Ehsaa, Al-Khobar, and Khamis Mushait. The study revealed that the mean prevalence of allergy in KSA is 24.7%. Using the locally prepared Saudi allergens, the most common allergens in KSA differed from one area to the other. They were Mites DF (49.1%), House dust mite (42.9%), and Mites DP (39.3%) in Al-Khobar, Mites DF (51.5%), Mite DP (48.5%), and house dust mite (39.8%) in Jeddah, Salsola kali (60.7%), Mites DP (52.3%), and Mites DF (48.6%) in Al-Ehsaa, Mites DP (56.7%), Mites DF (53.6%), Cat epithelium (46.4%) in Riyadh, and Salsola kali (54.7%), Mites DP (48%), and Prosopis (42.7%) in Khamis Mushait. These differences were attributed to many variable factors as environmental factors, geographical variation, and general change in indoor and outdoor environments. To assess the validity of Saudi allergenic extracts, they were compared to an imported kit; Canadian Omega kit. Although excellent validity was recorded for some allergens, validity of Saudi allergens was generally ranged from good to poor. This may be attributed to incomplete purity of collected allergens, different method for preparation and manufacturing, or may be due to different Saudi strain of the same allergen from the imported allergen. Adjustment of the methods of extraction, clarification, purification, and concentration of allergenic extracts was recommended. Reevaluation of methods and tools of allergy diagnosis in KSA keeping in consideration the common local allergens in the kingdom together with training of its physicians and doctors were also recommended.