What is Aspergillosis? - Fungal Infections & Symptoms

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  • 0:08 Airborne Parasitic Fungus
  • 0:53 Aspergillus
  • 3:00 Aspergillosis
  • 5:13 Diagnosis and Treatment
  • 6:39 Lesson Summary
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Lesson Transcript
Instructor: Angela Hartsock

Angela has taught college microbiology and anatomy & physiology, has a doctoral degree in microbiology, and has worked as a post-doctoral research scholar for Pittsburgh’s National Energy Technology Laboratory.

Human fungal diseases are rare and usually don't cause symptoms in healthy people. In this lesson, we'll discuss Aspergillus, a disease-causing mold, and the different infections and symptoms it can cause in susceptible hosts.

Airborne Parasitic Fungus

With every breath you take, you are inhaling a potentially deadly pathogen. You can't see this parasite floating into your nostrils and weaving its way down into your lungs. You probably breathe many of them right back out again, but some stick with every breath. If you're a healthy non-smoker, have no fear, your immune system has an excellent chance of destroying the invaders before they can make you sick. If your lungs or immune system are compromised, you still have an excellent chance of escaping these frequent attacks unscathed. But, for the unlucky few among us, the fungal pathogen Aspergillus might just win. Let's take a closer look and see what we could be in for.


Aspergillus is a genus made up of several species of molds that have the potential to cause serious fungal illnesses in humans and animals. This mold can literally be found everywhere, both inside buildings and outside in nature. The organism prefers to grow in decaying plant material but can also be found in high concentrations on stored grains, building materials, and common household dust. Aspergillus releases reproductive spores, which become airborne.

The only way to contract Aspergillus is to inhale those floating spores. You cannot get sick from person-to-person or person-to-animal contact, and you do inhale these spores every day of your life. The overwhelming majority of inhaled spores get eliminated by your immune system without issue. So, how does Aspergillus ever cause disease?

There are two major ways Aspergillus can shift from a common environmental contaminant to a potentially deadly pathogen. The first is if the spores are inhaled by a person that is susceptible to infection. This includes anyone with a compromised immune system or a chronic lung disease. People that have recently had an organ transplant, those on high doses of corticosteroids or cancer patients undergoing chemotherapy are often unable to mount a strong enough defense and Aspergillus can take hold. People with chronic lung disruptions like those with asthma, cystic fibrosis or smokers, also have a higher chance of getting sick from Aspergillus due to the increased irritation and inflammation present in the lung tissue.

The second way people can get Aspergillus is if they inhale a very large number of spores, too many for the normal immune response to handle. This usually occurs in people that are disturbing compost piles or cleaning up large areas of decaying plant matter, like what occurs after winter snow melt reveals wet autumn leaves. Construction workers are also at risk because building and renovations can stir up dust and high numbers of spores.


So, it's finally spring and you need to do your annual yard cleanup. Unfortunately, it was a great winter for Aspergillus, and you breathed in a significant number of spores. What can you expect?

Aspergillosis is any disease caused by the fungus Aspergillus. This sounds like a pretty worthless definition, but as you will see, Aspergillus can cause a wide variety of illnesses depending on where it ends up in the body. Most commonly, Aspergillus causes an allergic reaction, similar to the seasonal allergies that make the spring and fall unpleasant for millions of people. The infected host experiences wheezing and coughing, but the fungus does not actually do any damage to the lung tissues. If the Aspergillus settles in the sinuses, it can cause fevers and headaches as well.

Aspergillus in the lungs can become more severe if the fungus is able to grow unchecked by the immune system. Initially, the fungus can turn into a pulmonary aspergilloma, which is a round, tumor-like ball of filamentous fungal growth in the lungs. This mass can lead to shortness of breath and chest pains and always requires surgical removal. If Aspergillus is allowed to continue growing in the lungs unchecked, it can become invasive aspergillosis.

This is the most deadly type of infection in which the fungus spreads throughout the body. The parasite can invade other organs, interfering with normal function. Fungal masses can block blood vessels, cause inflammation in the heart lining and change mental function if it invades the brain. Symptoms can be variable depending on the organs invaded, but usually include bloody coughs, chills, fever, chest pains, headaches and shortness of breath. When invasive aspergillosis develops, treatment is required quickly, or it can be fatal.

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