What Is Aspergillus?

Medically Reviewed by Paul Boyce, MD on March 01, 2024
Written by Alyssa Anderson
3 min read

Aspergillus is a very common fungus. It can grow in many different environments and conditions, including the human body. 

There are over 200 different species of Aspergillus that we currently know about. Of these, at least 40 can infect humans. Aspergillus can infect some animals, too. 

People commonly come into contact with the Aspergillus fungus outside, because it grows well in the soil, on leaf litter and other decaying vegetation, and on seeds and grains. It can also appear indoors, particularly in buildings that have been damaged by water.  

Different species of Aspergillus are able to survive in both highly acidic and mildly basic conditions and at a wide range of temperatures. Some produce secondary metabolites called mycotoxins, and others make many different types of allergens. 

Aspergillosis is a condition that’s caused by contact with Aspergillus. 

Most people inhale Aspergillus spores or come into contact with the fungus every single day and don’t get sick. People with certain lung conditions or with compromised immune systems, though, are susceptible to developing a negative reaction from this fungus.

For the most part, aspergillosis can be divided into two broad categories—an allergic reaction or an invasive infection. There are five main types of aspergillosis: 

  • Allergic bronchopulmonary aspergillosis (ABPA). This is when Aspergillus enters your lungs and causes mild inflammation. Everything about this is comparable to an allergic reaction. You won’t develop an infection. 
  • Allergic Aspergillus sinusitis. This is when the fungus causes inflammation in your sinuses. It doesn’t develop into an infection. 
  • Chronic pulmonary aspergillosis. This is when Aspergillus infects your lungs. Large balls of the fungus—called aspergillomas—can form inside your lungs.  
  • Cutaneous (skin) aspergillosis. This form develops when Aspergillus enters your body through an opening—like a cut or burn—in your skin.  
  • Invasive aspergillosis. This is the most serious form of Aspergillus infection. The infection tends to start in your lungs but can spread throughout your body—to your brain, heart, and kidneys. People with weakened immune systems are the most vulnerable to this form of infection. 

The main cause of aspergillosis is inhaling Aspergillus spores or coming into contact with the fungus. This fungus is everywhere in the environment, and most people will come into contact with it at least once a day.  

The exact symptoms of your aspergillosis will depend on which type of condition you develop. 

For allergy-type conditions, the most common symptoms include: 

  • Wheezing
  • Coughing 
  • Shortness of breath
  • Stuffiness
  • Headaches

For the most severe form of infection—invasive aspergillosis—common symptoms include: 

  • Fever
  • Coughing up blood
  • Bleeding in your lungs
  • Chest pain
  • Shortness of breath

In severe cases, the infection will spread to other organs and will cause many more symptoms depending on where it goes. If left untreated, this form of aspergillosis can be fatal. 

Exactly how your aspergillosis is treated depends on which kind you have and how far your symptoms have progressed. Your particular treatment course may include: 

  • Observation. This will determine how severe your symptoms are and if any infections are spreading.  
  • Oral corticosteroids. These can help prevent symptoms from other lung conditions—like asthma and cystic fibrosis—from complicating the infection. 
  • Antifungal medications. This is a standard treatment for Aspergillus infections in your lungs. These medicines can have serious side effects, though, and some versions of Aspergillus are resistant to this type of medicine. If you are infected with a resistant strain, your fatality risk increases.
  • Surgery. This is mainly used to remove aspergillomas, the fungal masses that can develop in your lungs.
  • Embolization. You may need this procedure to stop any bleeding in your lungs.  

Aspergillosis is difficult to prevent. It’s found in so many locations and grows so well that you’ll never completely get it out of your environment. 

Instead, you want to focus on limiting your exposure to the fungus and its spores by: 

  • Protecting yourself from the environment. Avoid dusty areas entirely or wear an N95 facemask if you have to go somewhere dusty. Also, cover all of your skin if you have to garden or engage in other messy outdoor activities. If you get dirt in any wounds on your skin, wash them out as soon as possible with soap and water.
  • Taking preventative antifungal medications. Your doctor may recommend that you take a precautionary medication when you’ve had a surgery that puts you at risk for developing a severe infection, like an organ or stem cell transplant. More research is needed to determine exactly when this is a helpful precaution. 
  • Getting periodic testing for infection. People with compromised immune systems can get occasional blood tests to look for traces of the fungus. This way, they can catch the infection early, before it becomes too deadly.