Are Fungal Spores Relevant Outdoor Allergens?

Abstract

Alternaria alternata spores are important allergens causing "hayfever". Outdoor fungal exposure is primarily associated with increased asthma symptoms and increased risk of asthma exacerbations. In our outpatient-clinic, we investigated patients who presented with symptoms of allergic conjunctivitis and respiratory symptoms in the summertime. We found a sensitisation to Alternaria alternata in about 6 % of the investigated patients. Especially in children and teenagers, the sensitisation is clinically important. The spores of Alternaria alternata are responsible for the development and persistence of nonspecific airway hyperresponsiveness and in a group of patients also for a difficult-to-treat asthma in the summer. We should always bear in mind that prolonged symptoms (after end of June) in grass pollen allergic patients might be caused by additional sensitisation to Alternaria alternata spores or mugwort pollen. In our patients, we were able to show a sensitisation to Alternaria alternata in grass pollen allergic patients rather frequently. In the summertime, high counts of Alternaria spores and pollen often appear simultaneously. Our findings show a considerable effect of Alternaria sensitisation on the asthma morbidity and exacerbations. In this article we refer to the necessity of keeping a patient diary of allergic symptoms and the importance of information from regional pollen traps about the counts of pollen and Alternaria spores. Only then we will be able to differentiate, which allergen is responsible for the severe "hay fever", especially in patients with severe asthma episodes. Before the start of a specific immunotherapy with Alternaria alternata it is recommended to perform a mucosal provocation test, to prove the clinical significance of the sensitisation. It has been shown that also in Germany, there are high counts of Alternaria spores in the summer. The results of the pollen and alternaria count in the year 2009, measured in the regional pollen trap (Treuenbrietzen), are shown in Abb. 1, 2, 3, 4, 5. We have also found broken Alternaria spores. They are associated with increased asthma exacerbations and appear often during thunderstorms and harvesting. An allergen-specific immunotherapy with Alternaria alternata is a safe treatment and it is effective in improving respiratory function. The safety and efficacy is comparable to the one found in the allergen-specific immunotherapy with pollen.