Aspergillosis Causes

Aspergillosis is a condition caused by Aspergillus, an infectious mold. Aspergillus is a type of fungus found abundantly around us (indoors as well as outdoors). In individuals with healthy immune systems, the intake of this mold by breathing does not cause disease. However, in people with compromised immune systems, there is a high risk of developing aspergillosis due to inhalation of Aspergillus.

Aspergillosis is categorized into various types such as allergic Aspergillus sinusitis, chronic pulmonary aspergillosis, aspergilloma (also known as “fungus ball”), allergic bronchopulmonary aspergillosis (ABPA), and invasive aspergillosis. The majority of these are characterized by respiratory symptoms such as shortness of breath, wheezing, cough, and runny nose. Blood in sputum, weight loss, and chest pain are also seen in some cases.

Black mold fungi Aspergillus which produce aflatoxins and cause pulmonary infection aspergillosis. 3D illustration. Image Credit: Kateryna Kon / Shutterstock
Black mold fungi Aspergillus which produce aflatoxins and cause pulmonary infection aspergillosis. 3D illustration. Image Credit: Kateryna Kon / Shutterstock

In order to be able to treat the condition effectively, it is essential to understand the etiology of the disease.

Causes and Risk Factors

Exposure to Aspergillus spores in combination with a weak immune response is the root cause for the infection to take root. In healthy people, the immune system combats and destroys the mold spores effectively. This mechanism is compromised in people with various risk factors.

Individuals who are on immunosuppressant medications, especially after an organ transplant procedure, have a weakened immune response. Similarly, patients in the advanced stages of AIDS are also an easy target for opportunistic infections like aspergillosis. The extended use of corticosteroids is also associated with a poor immune defense. Depending on the other medications used concomitantly, and the type of underlying disease, the risk of opportunistic infections varies.

Lymphocytes, the white cells that play a major role in the natural defense mechanism of the body, usually fight the establishment of the infectious organisms within the body. However, in patients with certain vascular disorders such as chronic granulomatous disease, and some inherited genetic conditions that cause defects in lymphocyte function, the risk of developing aspergillosis rises substantially. Invasive aspergillosis is typically observed in individuals with compromised immunity.

Coexisting pulmonary conditions may further add to the odds of developing aspergillosis. In patients with chronic cystic fibrosis or asthma, the mold spores are likely to trigger an allergic response. Such patients are prone to developing ABPA.

Also in individuals with conditions like pulmonary tuberculosis or radiation damage to the alveoli, the air cavities in the lungs provide room for the accumulation of fungal fibers (the condition commonly referred to as “aspergilloma”).

Patients with other lung disorders such as chronic obstructive pulmonary disease (COPD) also often develop chronic pulmonary aspergillosis.

The fact that unlike many other microbial infections, aspergillosis is non-contagious, prevents this serious ailment from becoming an epidemic disease. It also precludes the need for isolation of the affected individuals. Physicians treat the aspergillosis patients on an individual basis, taking into account their medical history, comorbidities, and the type and severity of their infection.

Reviewed by Liji Thomas, MD.

Further Reading

Last Updated: Apr 9, 2018

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