Invasive Aspergillosis

Aspergillus species are ubiquitous molds found in the environment, most abundantly in soil and on decaying vegetation. The genus contains more than 200 species, with more than 30 species now reported to cause infections in humans. Aspergillus infection can present with a range of clinical syndromes, from localized colonization of the respiratory tract to devastating invasive disease. This In Brief focuses on invasive aspergillosis (IA). Although Aspergillus infection in immunocompetent patients is rare, it remains a significant cause of morbidity and mortality in immunocompromised patients. The incidence of IA infections has been increasing, likely related to more aggressive immunosuppressive therapies for certain conditions and increased survival in chronically immunosuppressed patients.

The incidence and severity of IA corresponds directly to a patients’ degree of immunosuppression. Patients with prolonged neutropenia are particularly at risk, with reports of an incidence of up to 70% in patients with neutropenia for greater than 30 days. In pediatric populations, the highest rates of IA occur in patients with hematologic malignancy, especially acute myelogenous leukemia. Hematopoietic stem cell transplant patients have 2 peaks of infection: one in the first 40 days after transplant and another 100 days or more after transplant. Later-onset infections are often related to high-dose corticosteroid therapy for graft-versus-host disease. Also, IA is seen in patients with chronic granulomatous disease and other inherited immunodeficiency conditions.

Aspergillus is transmitted through the inhalation of conidia (spores). Studies suggest that most people inhale several hundred Aspergillus conidia daily, but infection is avoided through the effective action of pulmonary macrophages and neutrophils. In patients who develop …