What Is Aspergillus Fumigatus?

Medically Reviewed by Poonam Sachdev on January 18, 2023
5 min read

Aspergillus fumigatus is a fungus that causes diseases in humans. If your immune system is weakened by disease or medication, this fungus can make you very sick. Aspergillus fumigatus is everywhere — it exists all around you in soil, air, and other organic matter. But your immune system can effectively deal with it if it's working as normal. The fungus can multiply and cause diseases if your immune system is not functioning properly.

Aspergillus fumigatus is a fungus of the class Eurotiomycetes and is widespread in nature. It's found in soil, decaying vegetation, air-conditioning and heating systems, and household items. It forms hardy spores (microscopic particles) that can survive for a long time. You could get infected by breathing these spores. 

This fungus doesn't grow and cause diseases if you have a healthy immune system. Aspergillus fumigatus is considered an opportunistic organism. It has low virulence (ability to cause damage) and causes disease only in some circumstances, like:

  • A severely weakened state caused by sickness, poor nutrition, advanced age, etc.
  • Immunosuppression by diseases or medicines
  • Implants use, such as prosthetic devices

Aspergillosis is an infection caused by this fungus. The spores grow into hyphae (the active form of the fungus) that cause diseases by tissue invasion, colonization, and allergic reactions. Your immune system cells can destroy the hyphae but not the spores.

Some conditions like chronic granulomatous disease, prolonged neutropenia, inherited immunodeficiencies, and acquired immunodeficiency syndrome (AIDS) put you at risk of getting sick. Aspergillus fumigatus infections in such situations are dangerous and often fatal.

The fungus spores (called conidia) enter your body in the air you breathe. They first reach the nose, throat, sinuses, and lungs. Aspergillus fumigatus causes disease by invading your tissues, preventing immune cell function, forming blood clots (thrombosis), and stimulating allergic reactions. 

In people with poor immunity, the infection may spread all over the body, including the brain and other organs. Aspergillus fumigatus symptoms depend on the part of the body infected and your own immunity. Some disorders caused by this fungus are:

Chronic pulmonary aspergillosis (CPA). This is a condition in which the fungus grows slowly in the lungs. The lungs are slowly damaged by inflammation and scarring, and symptoms may only show after months or years. The common symptom is coughing. Other symptoms are weight loss, tiredness, and breathlessness. If the growing fungus damages a blood vessel, you may cough up blood (hemoptysis). Coughing up blood is a serious symptom, and you should go to a hospital immediately.

Invasive aspergillosis. It's a life-threatening condition and happens to people who are severely immunocompromised (have a weak immune system). The fungus grows rapidly, and the lungs are affected most often. Invasive aspergillosis may involve the sinuses, ears, skin, or eyes. The symptoms depend on the organ affected by the condition.

Aspergillomas. These are round fungal balls created by the growth of the fungus in a lung cavity. These often don't cause symptoms until they damage a blood vessel and cause you to cough up blood. Other forms of lung infections caused by Aspergillus fumigatus are aspergillus nodules and chronic fibrosing pulmonary aspergillosis. They often cause no symptoms or only non-specific ones like cough, tiredness, and weight loss.

Fungal sinusitis.Aspergillus fumigatus spores often reach the sinuses and multiply there. They can cause symptoms by tissue invasion and provoking allergic reactions. Symptoms are similar to other types of sinusitis like nasal stuffiness and difficulty breathing, facial pain, headaches, thick green or dark nasal discharge, and mucus along the back of the throat.

Aspergillus species are not dermatophytes (fungi that cause skin disease) and don't often infect the skin. But Aspergillus fumigatus can sometimes cause onychomycosis, an infection of the nails.

Aspergillus fumigatus infections are dangerous and often lead to death. The fungus can also cause allergic conditions like allergic bronchopulmonary aspergillosis (ABPA) and allergic sinusitis. These cause sickness and symptoms but are rarely fatal.

You're likely to have ABPA if you already have a lung condition like cystic fibrosis, bronchiectasis, or asthma. This condition is an allergic reaction to inhaled spores of Aspergillus fumigatus. Spores not quickly removed by the immune system swell and release toxins. These toxins trigger an inflammatory reaction that causes asthma-like symptoms, such as wheezing, cough, and breathlessness.

These symptoms are triggered when you're near sources of airborne spores of Aspergillus fumigatus. This includes compost heaps, damp buildings, and other environments that favor fungi. Your doctor can confirm this diagnosis by some tests that show:

  • Eosinophilia (increased numbers of eosinophils, a type of white blood cell, in your blood)
  • Skin test reaction to Aspergillus antigen tests
  • Antibodies to Aspergillus in your blood
  • Increased blood levels of IgE (a type of immunoglobulin)
  • X-ray changes

The treatment of this fungal infection requires antifungal drugs, but they're not always effective in removing the infection. Commonly used medicines are amphotericin B, caspofungin, itraconazole, micafungin, and voriconazole.

Aspergillomas are large fungal balls that don't respond well to medicines alone. They should be removed by surgery, and antifungal medicines should be given afterward. Similarly, fungal sinusitis needs the establishment of drainage of the affected sinus. Sinus surgery provides relief. Medicines (antifungals) are not effective in the treatment of fungal sinusitis.

If you have ABPA, your symptoms are allergic in origin. Your doctor will prescribe steroids, such as prednisolone, to control your symptoms. It's not possible to cure the fungal infection completely. But antifungal medicines like itraconazole can reduce the steroid dose required and the side effects. Another effective drug is omalizumab, an antibody that reduces inflammation in the airways. Controlling inflammation is crucial to preventing ongoing lung damage. It will also relieve your symptoms.

If you've had a stem cell transplant, lung or other organ transplant, or certain other conditions, you're at high risk for Aspergillus fumigatus infection. Your doctor may prescribe antifungal medicines as a preventive measure.

Aspergillus fumigatus is sometimes resistant to the commonly used antifungal medicines. Azoles are an important class of antifungal medicines and the most frequently used medicines for the treatment of Aspergillus fumigatus infections. Azole-resistant Aspergillus fumigatus is considered a significant danger by the Centers for Disease Control and Prevention (CDC). Resistance to medicines makes treatment difficult. People with azole-resistant infections are 33% more likely to die.