An invasive fungal disease (IFD) is a life-threatening infection that is almost exclusively diagnosed in immunocompromised hosts. The most common invasive mould infection is caused by Aspergillus species and called invasive aspergillosis (IA). Patients with acute myeloid leukaemia who are treated with intensive chemotherapy and hematopoietic stem cell transplant recipients are at highest risk for IA. Incidence rates of IA vary substantially and depend on host and environmental factors but also the modalities of allogeneic stem cell transplantation recipients as well as the use of antifungal prophylaxis. Without prophylaxis the incidence of IA in these populations can be as high as 10–20%.1–3 IA does not only lead to a higher overall mortality and morbidity but also to substantially higher medical costs.4 The case fatality rate of IA is estimated to lie between 20–38%, six to twelve weeks after diagnosis but this as well varies substantially between populations.5 Therefore, optimising the management of IA is key in order to reduce the burden of this devastating complication in the immunocompromised host. For more than fifteen years voriconazole, a drug of the triazole class, has been the recommended treatment for this life-threatening infection after a pivotal randomised trial showed an improved survival with voriconazole compared with amphotericin B deoxycholate. However, also with voriconazole and improved diagnostic tests, the overall 6-week mortality is still unacceptably high at 25–30%.6 A troublesome emerging problem in patients with IA is the increasing incidence of infections with triazole-resistant A. fumigatus. Although limited by numbers, case series have demonstrated that the overall mortality of patients infected with triazole-resistant A. fumigatus is very high (50–88%).7,8 This thesis focuses on risk factors for and the diagnosis of invasive aspergillosis. Additionally, the management of azole-resistant aspergillosis is addressed. The thesis consisted of several chapters. You can read all chapters in the digital version of the thesis. We briefly summarise the most important findings in every chapter.

(BELG J HEMATOL 2021;12(8):353–4)