Emerging pathogens

The ever increasing numbers of immunosuppressed individuals has led to a si gnificant increase in the incidence of opportunistic infections, particular ly those caused by fungi. The epidemiology of infections caused by the comm on fungal pathogens such as Candida albicans. Cryptococcus neoformans and A spergillus fumigatus has been well documented. However, in addition to thes e, a number of species which have previously been unrecognized (e.g., C. du bliniensis) or have previously been assumed to be non-pathogenic (e.g., Sac charomyces cerevisiae, Scedosporium spp. and Fusarium spp.) have emerged as agents of human disease. Since these species have only been identified rec ently as human pathogens, their role in disease is poorly understood. In mo st cases, identification of these species is problematic and therefore thei r epidemiology has yet to be elucidated adequately. In addition, several of these species fail to respond to conventional antifungal therapies. In thi s article, we describe the emergence of two separate yeast species (C. dubl iniensis and S. cerevisiae) and two separate groups of moulds (Scedosporium prolificans and Fusarium spp.), as human pathogens. It is apparent from wh at we already know, that much work has yet to be performed before we have a clear understanding of how these species cause disease and most importantl y how they can be controlled.