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The dispersal of rodent-borne strains of Aphanoascus keratinophilus and Chrysosporium tropicum by pellets of predatory birds

Posted on 18. December, 2017.

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Pathogenic species of yeast, yeast-like fungi and moulds have been recovered from faeces, feathers, beaks and cloacae as well as pellets of species of migratory and sedentary birds. Bird pellets, in particular pellets of predatory birds, are an especially suitable model for studies of circulation routes of dermatophytes and other keratinophilic fungi as they contain undigested food remains, which are rich in keratin (e.g. feathers, fur). 


The species composition of keratinophilic fungi in 153 pellets of nine species of predatory birds was analysed. Based on morphological criteria, a total of 439 strains of non-dermatophytic fungi of the Chrysosporium group were isolated and identified. Dermatophytes were not detected. The collection was verified using molecular methods, such as PCR-RFLP (restriction fragments length polymorphism) and two potentially pathogenic species, Aphanoascus keratinophilus and Chrysosporium tropicum, were detected. Pellet colonisation by these fungi ranged between 37.5% and 91.7% depending on the bird species. As the analysis of undigested remains found in the pellets showed, rodents, mostly Microtus, which constituted from 57% to 100% of the birds’ diet, were a chief source of A. keratinophilus and Ch. tropicum strains. It was demonstrated that the survival and dispersal of A. keratinophilus strains was supported by higher pellet moisture while those of Ch. tropicum strains by drying, which was conditioned by the site where pellets were dropped and deposited by individual species of predatory birds. Based on the results, circulation routes of both opportunistic pathogens using pellets of predatory birds as carriers are proposed.

Keywords: Aphanoascus keratinophilus, Chrysosporium tropicum, pellets of predatory birds, occurrence

Authors: Anita Ciesielska, Teresa Korniłłowicz-Kowalska, Ignacy Kitowski, Justyna Bohacz

Read the full article in Avian Biology Research, Volume 10, Number 4, December 2017, pp. 218-230