Last update:
17-Sep-2004

A pernicious group of pathogens, which especially affect immunocompromised individuals are found in the Genus Aspergillus. A series of properties make them extremely successful and dangerous organisms, combined with their worldwide spread. These factors are found primarily in the "peripatetic" form of the fungus, that is in its conidia, which have acquired, through evolution, all the necessary skills and qualities to survive journeys of extra long distances in harsh environment as saprophytes. Metabolic and aerodynamic properties allow the fungus to approach, enter and adhere to the host tissue, to survive, under certain conditions, in a very harsh microenvironment (as is the living human body) and finally to germinate, grow and multiply, producing lifethreatening infections. Another set of properties, which may well have been acquired and passed on through evolutionary pathways, seems to be oriented towards nullifying the immunologic procedures of the human organism. These processes, with differential timing and diverse degrees of success, mainly concentrate around cellular immunity and use, to a varying extent, the various kinds of phagocytes, exploiting an array of predisposing host factors. This by no means implies an absence of alternative virulence determinants and procedures at cellular, sub-cellular and cell-free levels, such as complement, natural killer cells, free radicals, a variety of mutagenic or co-carcinogenic primary and secondary metabolites.

Key words: Aspergillus, Conidial aerodynamics, Immune response suppression, Virulence determinants.