What are the causes?
Aspergillus are saprotrophic fungi in the environment that grow on decaying vegetation in soil. Aspergillus fumigatus is the species most often involved in disease in humans.
How is the fungus transmitted?
Aspergillosis is not contagious between individuals. The disease is transmitted by inhaling Aspergillus spores in the air. In healthy individuals, the fungus is rapidly eliminated. Aspergillus becomes pathogenic in patients with chronic lung disease or immunosuppression, generally caused by medical treatment.
What are the symptoms?
The symptoms of aspergillosis vary considerably depending on the type of infection. It mostly affects the lungs, and it may cause respiratory symptoms such as a cough, difficulty breathing or chest pains, as well as more general symptoms like fever. In some cases, aspergillosis may spread through the body to other organs such as the brain.
What are the different forms of aspergillosis?
Depending on the patient's medical condition, Aspergillus may be responsible for several diseases:
- Allergic bronchopulmonary aspergillosis (ABPA), mainly in patients with asthma or cystic fibrosis, is caused by both a failure to eliminate the fungal spores and an excessive reaction from the patient's immune system to the fungus.
- Chronic pulmonary aspergillosis affects patients with a pre-existing lung condition such as a tuberculous cavity (following tuberculosis infection) or chronic obstructive pulmonary disease (COPD). It may take the form of an aspergilloma or chronic cavitary aspergillosis.
- Invasive aspergillosis mainly affects immunocompromised patients (such as patients with neutropenia or those who have received a bone marrow transplant). It is characterized by severe infection, with Aspergillus invading the lung tissue. The infection may spread to other organs in this form. There is a form of invasive pulmonary aspergillosis associated with severe viral infections (such as influenza or SARS-CoV-2) among patients in intensive care.
How is aspergillosis diagnosed?
Invasive aspergillosis is a difficult infection to diagnose because the symptoms are similar to those caused by bacterial infections. Chest imaging, especially a CT scan, is a helpful diagnostic tool, particularly for immunocompromised patients. Microbiological diagnosis involves combining several markers, including culture and detection of specific antigens or fungal DNA from a blood or deep respiratory sample (using a galactomannan antigen test or Aspergillus PCR).
What treatments are available?
- Allergic bronchopulmonary aspergillosis: Treatment is based on the use of corticosteroids, sometimes in combination with an oral antifungal drug.
- Chronic pulmonary aspergillosis: Treatment depends on the size and location of the lesions. It can range from active monitoring to antifungal treatment or surgery. Hemoptysis (coughing up blood) is a warning sign that requires emergency medical attention and specific treatment.
- Invasive aspergillosis: First-line treatment is an azole antifungal agent such as voriconazole or isavuconazole, to be administered immediately if infection is suspected. Second-line treatments are posaconazole or amphotericin B. The emergence of Aspergillus resistant to these azole drugs is a growing problem in some countries as a result of widespread azole use in agriculture, but as yet it is not a cause for concern in France. Treatment should also involve management of the underlying disease and immune system boosting.
How can aspergillosis be prevented?
There is no vaccine for aspergillosis. Prophylaxis is crucial for at-risk patients such as bone marrow transplant recipients, for whom posaconazole is used as a first-line treatment.
How many people are affected?
Invasive pulmonary aspergillosis is the third most common invasive fungal infection in France, with a high case fatality rate of between 50 and 80%.
November 2024