The aim of the study was to assess the concentration of the major airborne pathogenic fungal spore over paddy fields with an object to identify the fungal allergen which are causing respiratory allergy among farmers, by immune-clinical techniques.
Method:Volumetric assessment of airborne culturable and non-culturable fungal spores was performed in the experimental site (North 24 Parganas, West Bengal, India) for 2 consecutive years (November 2011–October 2013) by using an Andersen Two Stage volumetric sampler and a Burkard Personal Slide Sampler for trapping culturable and non-culturable types of fungal spores. Culturable fungal spores were sub-cultured in medium for isolating and identifying individual species. The fungal antigens were prepared from the prevalent culturable types of selected fungal spores in Y-cell lysis reagent (buffer). The allergenic potential of the antigens were evaluated on atopic farmers by SPT (in vivo) followed by ELISA & IgE-specific Immunoblotting (in vitro). The antigens resolved in 11% SDS PAGE and IgE-reactive allergen were identified by western immunoblotting.
Result:A total of 34 types of fungal spore and 24 types of viable colony-forming fungal spores were recorded. The major perennial cultured fungal spore types included Aspergilli group, Fusarium oxysporum, Cladosporium cladosporioides, Nigrospora oryzae, Helminthosporium oryzae, Alternaria alternata, Drechslera sp. etc. showed higher sensitivity in SPT. Among these fungal spores Aspergilli group (A.niger, A. fumigatus, A. flavus, A. clavatus, Penicillium claviforme) showed highest (23.7%) reactivity followed by Fusarium oxysporum, Helminthosporium oryzae, Alternaria alternate, Cladosporium cladosporioides, Nigrospora sp. in SPT carried out in 214 adult agricultural field workers with respiratory disorders. Total fungal protein of A.niger, A. fumigatus, A. flavus, A. clavatus, Penicillium claviforme, Fusarium oxysporum, Helminthosporium oryzae, Alternaria alternate, Cladosporium cladosporioides, Nigrospora sp. resolved into 11,15,17,13,16,12,10, 18,13 and 12 distinct bands respectively in 11% SDS PAGE and in immunoblotting 5, 6, 4, 6, 7, 3, 4, 4, 5 and 3 IgE reactive allergens were identified respectively.
The airborne fungal spores not only cause the pathogenic infection to rice plants but also cause respiratory allergy among the paddy field farmers. Western immunoblotting revealed the major IgE reactive fungal allergens. The finding indicates that occupational allergy to fungal spores is an important health hazards among farmers of West Bengal.