Yeasts in birds

Abstract

Wild animals, particularly birds, play a relevant role in disseminating microscopic organisms, including yeasts and filamentous fungi. The ecology of yeasts associated with birds has been studied mainly for the urban avifauna, and little is known about yeasts associated with wild birds including migratory species. Recent findings on the adaptation and persistence of yeasts in animals suggest that birds can play an important role in the ecology and distribution of yeasts. It has been shown that birds can vector pathogenic fungi by disseminating fungal cells from the cloacae in the environment via their excretions. Wild birds, especially pigeons and their feces, represent a reservoir for pathogenic yeasts, and the genera Cryptococcus and Candida are the most frequently isolated yeast genera from birds. The contact with birds, in particular with their excretions, is considered one of the main causes of cryptococcosis and candidiasis. Dispersal of nonclinical yeasts by birds is important for agriculture because microbial communities affect the quality of food products such as some fermented foods. Insect vectors have been recognized as source of extraordinary large yeast diversity in many studies. Migratory birds are able to travel over large distances and carry yeasts even between continents. Compared to insects, our knowledge of yeasts associated with birds is limited. The present chapter provides an overview on birds as a reservoir for pathogenic yeasts and reviews studies on migratory birds acting as dissemination vectors of yeasts.