Aspergillus infections have grown in importance in the last years. However, most of
the studies have focused on Aspergillus fumigatus, the most prevalent species in the
genus. In certain locales and hospitals, Aspergillus flavus is more common in air
than A. fumigatus, for unclear reasons. After A. fumigatus, A. flavus is the second
leading cause of invasive aspergillosis and it is the most common cause of superficial
infection. Experimental invasive infections in mice show A. flavus to be 100-fold
more virulent than A. fumigatus in terms of inoculum required. Particularly common
clinical syndromes associated with A. flavus include chronic granulomatous sinusitis,
keratitis, cutaneous aspergillosis, wound infections and osteomyelitis following trauma
and inoculation. Outbreaks associated with A. flavus appear to be associated with
single or closely related strains, in contrast to those associated with A. fumigatus.
In addition, A. flavus produces aflatoxins, the most toxic and potent hepatocarcinogenic
natural compounds ever characterized. Accurate species identification within Aspergillus
flavus complex remains difficult due to overlapping morphological and biochemical
characteristics, and much taxonomic and population genetics work is necessary to better
understand the species and related species. The flavus complex currently includes
23 species or varieties, including two sexual species, Petromyces alliaceus and P.
albertensis. The genome of the highly related Aspergillus oryzae is completed and
available; that of A. flavus in the final stages of annotation. Our understanding
of A. flavus lags far behind that of A. fumigatus. Studies of the genomics, taxonomy,
population genetics, pathogenicity, allergenicity and antifungal susceptibility of
A. flavus are all required.