Ecology of yeast and epidemiology of yeast infections.

In the normal human flora yeasts occur regularly and most of them are potential pathogens. Apart from C. albicans, C. glabrata and P. orbiculare they originate mainly from sources outside man. Thus Cryptococcus neoformans has its main reservoir in pidgeon manure. The epidemiology of yeast infections and more particularly those caused by C. albicans has not been well understood until recently when 3 different methods have been developed that allow for differentiation of strains of C. albicans. These methods are based on sensitivity to various chemicals, results of various biochemical tests and the sensitivity to various killer toxins. The methods have made it possible to trace the source and spreading of C. albicans, and may prove useful also in the differentiation of other yeast species.