David R. Snydman, Section Editor

Invasive fungal infections are common and deadly in recipients of blood and marrow transplants. Current diagnostic tech-niques do not allow accurate early diagnosis, especially of infection with mould pathogens, and delays in diagnosis are associated with treatment failure. This lack of early diagnosis has provided the impetus for the development of antifungal prophylaxis. Fluconazole prophylaxis is highly effective for the control of invasive yeast infections and associated with few breakthrough infections. The development of antimould prophylaxis in this patient population is a high priority. THE NATURE OF THE PROBLEM Invasive fungal infection has always been a major cause of morbidity and mortality in recipients of blood and marrow transplants (BMTs). As transplantation practices have evolved to include potent immunoprophylaxis regimens, which result in more-prolonged immunodeficiency after transplantation and in association with greater use of mismatched transplants, the incidence of invasive fungal infections is increasing, even in the face of measures taken to reduce their impact. Today, invasive fungal infections pose the chief infectious challenge to the BM