Seasonal and geographic variation of environmental burden of dematiaceous fungi in North India

The dematiaceous fungi cause numerous infections in both immunocompetent as well as immunocompromised individuals. The route of infection is either respiratory or subcutaneous/ocular implantation. Despite the rising incidence of these infections, very few studies have been conducted to decipher the seasonal and geographic variation of environmental burden of these fungi. We conducted environmental surveillance (both vegetation and air) to determine seasonal spore burden of dematiaceous fungi in urban and rural regions of North India, namely Punjab, Haryana, Chandigarh and Himachal Pradesh (HP). A total of 1748 environmental samples [soil, plants leaves and decayed vegetation (n=460 each), and air (n=368)] were collected. Mean spore count (x10 3 CFU/m 3 ) of dematiaceous fungi was highest in plants (7.32-39.3) followed by soil (2-32.9), and decayed vegetation (2.33-28.6) and lowest in air (0.07-0.50). The spore count in plant samples was significantly higher in rural areas of HP. Spore burden was noted to be high in summer, being statistically significant in Haryana. Alternaria spp, Curvularia spp, Bipolaris spp, Cladosporium spp, were the predominant species in both air and soil/plants/vegetation . Rare fungi included Cephalotrichum spp , Verruculosa spp, Cladosporium velox, Hawksworthiomyces spp and Fonsaecea spp. Interestingly, we isolated rare pathogenic species of Cladosporium halotolerans, Cladosporium tenuissimum, L. prolificans and Ochroconis mirabilis. The present study showed a high environmental spore burden of dematiaceous fungi in North India. This underscores requisite to further establish the epidemiological link between clinical cases and environmental abundance of spores of these dematiaceous fungi along with effect of air/soil composition affecting the same.