Airborne alternaria spores: potential allergic sensitizers in Saudi Arabia

ABSTRACT

In order to investigate the role of airborne Aternaria 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. 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. Alternaria spores constituted between 1.9%-9.6% of the total fungal air spora, and the maximum concentration exceeded 5xl0[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 Aternaria 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. 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 Aternaria allergens. The study suggests that airborne Aternaria 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