In immunosuppressed hosts: invasive pulmonary infection, usually with fever, cough, and chest pain. Infection may disseminate to other organs, including brain, skin and bone.
In immunocompetent hosts: Localized pulmonary infection in people with underlying lung disease, allergic bronchopulmonary disease, and allergic sinusitis.
Most commonly, Aspergillus fumigatus and A. flavus. Less common species include A. terreus, A. nidulans, A. niger, and A. versicolor.
Aspergillus is ubiquitous in the environment; it can be found in soil, decomposing plant matter, household dust, building materials, plants, food, and water.
Transmission occurs through inhalation of airborne conidia. Hospital-acquired infections may be sporadic or may be associated with dust exposure during building renovation or construction. Occasional outbreaks of cutaneous infection have been traced to contaminated biomedical devices. The incubation period for aspergillosis is unclear and likely varies depending on the dose of Aspergillus and the host immune response.
CDC’s Healthcare Infection Control Practices Advisory Committee (HICPAC) has developed guidelines for environmental infection control.
A definitive diagnosis of aspergillosis typically requires a positive culture from a normally sterile site and histopathological evidence of infection. Other diagnostic tools include radiology, galactomannan antigen detection, Beta-D-glucan detection, and polymerase chain reaction (PCR).
- Microscopy: Evaluation of respiratory specimens after the application of special stains can allow for visualization of Aspergillus elements. They appear as septated hyphae with acute angle branching. However, definitive identification is difficult to make by this method alone as it is insensitive and even when positive, several filamentous fungi have a similar microscopic appearance.
- Histopathology: Important for documentation of invasive disease. Similar to microscopy, Aspergillus appears as septated hyphae with acute angle branching and can be mistaken for other filamentous molds.
- Culture: Can be done on a variety of sterile specimens and Aspergillus spp. present as rapidly growing molds that are visible 1-3 days after incubation. Culture allows for the microscopic identification down to the species level; however, this method is relatively insensitive, so patients with invasive aspergillosis may have negative cultures.
- Galactomannan antigen test: This test detects a polysaccharide that makes up part of the cell wall of Aspergillus spp. and other fungi. The Platelia (Bio-Rad Laboratories) assay is approved by the US Food and Drug Administration (FDA) for serum and bronchoalveolar lavage fluid. False positive tests have been reported in association with administration of certain antibiotics and cross reactivity exists with other fungal infections, such as those due to Fusarium spp. or Histoplasma capsulatum.
- Beta-d-glucan assay: This test also detects a component in the cell wall of Aspergillus spp, as well as other fungi. The Fungitell® assay has been approved by the FDA for diagnosis of invasive fungal infections, including those due to Aspergillus, Candida, and Pneumocystis. Similar to galactomannan testing, the specificity of this assay is reduced in a variety of clinical settings, including exposure to certain antibiotics, hemodialysis, and co-infection with certain bacteria.
- Polymerase Chain Reaction (PCR): PCR for detection of Aspergillus spp. from clinical specimens, including tissue and bronchoalveolar lavage fluid, is offered by some laboratories.
Risk groups for invasive aspergillosis include persons who have severe/prolonged granulocytopenia, hematologic malignancies, receipt of a hematopoietic stem cell or solid organ transplant, and high-dose corticosteroids or other immunosuppressive therapies.
Risk groups for allergic aspergillosis include persons who have asthma, cystic fibrosis, or other underlying lung diseases.
Surveillance and statistics
Areas for further research
- Developing more sensitive and specific methods for earlier diagnosis
- Improving our understanding of environmental sources and routes of transmission
- Improved availability of advanced molecular typing methods to assist in epidemiologic studies
- Developing surveillance for resistant Aspergillus infections