Assessment of allergenicity to fungal allergens of Rohtak city, Haryana, India

Fungal spores are known as one of the important bioparticles causing allergic manifestation in human beings. Hence, knowledge of season and prevalence of the airborne allergens to which the patients are exposed is a prerequisite for proper diagnosis and treatment of allergic disorders in hypersensitive individuals. Keeping this in view, aerial survey was performed in the atmosphere of Rohtak city for 2 consecutive years (March 2008-February 2010), using a volumetric petri plate sampler. A total of 45 fungal spore types were recorded during the survey period. In the present study, February-April and July-November were identified as the peak seasons for Rohtak city. Cladosporium was the main contributor to the total fungal load with 25.14% followed by Alternaria (18.05%), Aspergillus niger (7.66%), Curvularia (5.31%), and Epicoccum (5.29%). Fifteen dominant viable fungal spore types were represented in the form of a fungal calendar. An attempt has also been made to assess the allergenicity of some of the fungal types recorded from the atmosphere of Rohtak city. The magnitude of variations observed in markedly positive skin reactions (2+ and above) varied from 17.3 to 2.3%. Penicillium oxalicum showed a markedly positive reaction in maximum number of patients (26; 17.3%) followed by Rhizopus nigricans (23; 15.3%). ELISA was performed with the sera of patients showing markedly positive skin reactions and the sera were classified into four groups based on percent binding. The majority of the sera showed 0-15% binding to different antigenic extracts, while sera showing >60% binding were least in number. Greater than 30% binding was observed against antigens of Rhizopus nigricans, Epicoccum purpurascens, Penicillium oxalicum, Curvularia lunata, Aspergillus flavus, Candida albicans and Neurospora sitophila. The concordance between positive skin reaction and serum-specific IgE antibodies ranged from 16.7 to 69.2%.