- Clinical science
Aspergillosis is the collective term for diseases caused by mold species in the genus Aspergillus. Aspergillus spores are ubiquitous but do not usually cause infection in immunocompetent individuals. Risk factors for Aspergillus infection include immunosuppression (e.g., HIV, hematologic malignancies, transplant recipients) and underlying pulmonary conditions (e.g., cavernous tuberculosis, COPD). Infections may be localized, causing asymptomatic pulmonary aspergilloma, or symptomatic, complicated infiltrates (e.g., with cavitation, fibrosis, or necrosis). In immunocompromised patients, invasive aspergillosis is common, which manifests as severe pneumonia and septicemia with potential involvement of other organs. In patients with pre-existing bronchopulmonary conditions (e.g., asthma, cystic fibrosis), Aspergillus may cause allergic bronchopulmonary aspergillosis (ABPA), which presents with asthmatic symptoms or sinusitis. Elevated serum IgE levels and eosinophilia indicate a fungal infection. Tissue biopsy followed by histopathology and culture are used to confirm the diagnosis. Medical treatment for aspergillosis infection includes voriconazole, caspofungin, or amphotericin B. An aspergilloma, on the other hand, must be surgically removed. ABPA is primarily managed with glucocorticoid therapy. Immunocompromised patients should receive prophylactic posaconazole.
Transmission: airborne exposure to mold spores
- Aspergillus spores are ubiquitous indoors, as they enter with the normal flow of air.
- The spores can also settle on easily accessible sources of nutrition (e.g., water), dust, cellulose (e.g., in wallpaper), and indoor plants Aspergillus spores can germinate and grow when conditions are optimal – e.g., at temperatures between 20–25°C or 68–77°F, with humidity at around 80%.
- Aspergillus spores may also be found in intensive care units
- Risk factors
- Chronic exposure to Aspergillus can lead to allergic bronchopulmonary aspergillosis (ABPA)
- Sinusitis without tissue infiltration
- Nonspecific symptoms: weight loss, chronic fatigue; irritation of the skin, mucus membranes, and eyes
- Possible clinical manifestations
- Clinical features
- Lungs: pulmonary aspergillosis
- Mucous membranes in sinuses
- Skin (via direct inoculation):pustules or hemorrhagic papules/plaques, which may evolve into eschars
- Disseminated infection
- History of asthma or cystic fibrosis
- Positive Aspergillus antigen skin test OR ↑ IgE levels against A. fumigatus
- Serum IgE > 1000 IU/mL
- Total eosinophil count > 500 cells/μL in patients with no history of glucocorticoid use
- Laboratory tests: ↑ ESR and eosinophilia
- Tissue biopsy followed by histopathology and culture → Positive findings (e.g. presence of monomorphic, septate hyphae that branch at acute angles, as seen on silver or PAS stained samples) confirm the diagnosis of aspergillosis infection.
- X-ray and CT: parenchymal opacities; features of
The following criteria should be fulfilled for each type:
X-ray and CT
- Monad sign: a peripheral air crescent around a fungus ball in a pre-existing lung cavity
Radiological evidence of a mobile fungus ball
- The mobility of the fungus ball is demonstrated by moving the patient from a supine position to a prone or lateral recumbent position.
- The upper lobe is mostly affected because of the increased concentration of oxygen
- Laboratory tests: positive sputum culture or positive Aspergillus IgG serology
- X-ray and CT
- Aspergillus nodule
- Cavitary pulmonary aspergillosis
- Fibrotic aspergillosis → criteria as in cavitary pulmonary aspergillosis + extensive fibrosis on CT or biopsy
- Necrotizing aspergillosis → criteria as in invasive aspergillosis
- Multiple nodules
- Halo sign: hemorrhagic ground glass opacities around nodules
- Sickle-shaped air crescents around the fungal colony
- Positive galactomannan antigen test
- Positive 1,3-β-D glucan test
- If CNS infection is suspected: cranial MRI
- Chest CT
Confirmatory test: positive culture and/or histopathological evidence of invasive aspergillosis
- Bronchoalveolar lavage via bronchoscopy
- In patients with peripheral nodular lesions on imaging: endobronchial lung biopsy via bronchoscopy or CT-guided percutaneous biopsy
- Specimen collection
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The differential diagnoses listed here are not exhaustive.
- Avoid aspergillus exposure
- Consider adding itraconazole: may be added for 16 weeks.
- In addition, in the presence of sinusitis:
- Endoscopic drainage
- Surgical resection of nasal polyps
- Possible nasal wash with antimycotics
Asymptomatic patients without disease progression do not require treatment, but regular follow-up with imaging and Aspergillosis antibody titer tests are nonetheless absolutely necessary.
- Definitive treatment: surgical resection (e.g., lobectomy) of the aspergilloma
- Antifungals (e.g., oral itraconazole or voriconazole) should be used preoperatively and postoperatively (for 4–12 weeks)
- In the event of massive hemoptysis: bronchial angiography and embolization for temporary stabilization
- Aspergillus nodule: antimycotic treatment
- Other chronic pulmonary types
- Treatment of choice: IV voriconazole
- HIV-infected patients: HIV antiretroviral therapy should be initiated as soon as possible or adjusted after consulting an HIV specialist
- Protective measures: to improve the immune status of the patient
- Indication: severely immunocompromised patients
- Drug of choice: posaconazole (IV loading dose followed by oral maintenance therapy)
Reduction of mold exposure
The following measures reduce the risk of indoor mold exposure according to the CDC guidelines:
- Protective measures taken during the construction of buildings, both indoors and outdoors:
- Adequate insulation
- Sealing of the floor to prevent moisture from the soil from entering and pervading it
- Protection from driving rain
- Regular re-roofing
- Ensuring the floors and roofs are watertight.
- Adequate dust cover measures need to be incorporated during construction and restoration work so that there is reduced exposure to the mold present in the dust that is normally stirred up.
- Protective measures taken at home:
- Use a ventilation hood while cooking, add mold inhibitors to wall paint, use mold killers in bathrooms, ensure regular ventilation (complete opening of the windows for 5–10 min) and adequate heating (especially in winter) in order to keep the humidity as low as possible.
- Avoid drying laundry indoors, use of humidifiers, and carpets in bathrooms.