Invasive fungal diseases in immunocompetent adults: emerging patterns and clinical challenges

Invasive fungal diseases (IFDs) have traditionally been regarded as complications of classical immunosuppression. However, IFDs are increasingly recognized in adults who are apparently immunocompetent or non-neutropenic, particularly in the setting of severe viral pneumonia, critical illness, diabetes, structural lung disease, surgery, trauma or burns, injection or inhalational drug use, invasive devices, broad-spectrum antibiotics, and previously unrecognized immune dysregulation.

This narrative review summarizes emerging patterns and clinical challenges of IFD in apparently immunocompetent adults, integrating invasive molds, endemic dimorphic fungi, and invasive yeasts.

The current landscape includes influenza- and COVID-19-associated pulmonary aspergillosis, COVID-19-associated mucormycosis, acute invasive mold disease in critically ill patients, tissue-injury- and trauma-associated mold infections, severe endemic mycoses after relevant environmental exposure, and an expanding spectrum of invasive yeasts. The label "immunocompetent" often conceals situational immune dysfunction or an undiagnosed inborn or acquired immune defect. Cohort data are available for several non-classical host groups, whereas evidence for truly healthy adults remains dominated by small series and case reports.

In adults without classical immunosuppression, IFD should be suspected when clinical deterioration occurs in the setting of acute illness, disruption of skin or mucosal barriers, indwelling catheters, healthcare exposure, unusual clinical syndromes, relevant geographic exposure, or unrecognized immune defects.