Aspergillosis is an infection caused by the Aspergillus fungus or an allergic reaction to the fungus. Learn more about aspergillosis and the fungus that causes it.

WHAT IS IT?

Overview

Aspergillosis (pronounced a·sper·juh·low·suhs) is an infection or allergic reaction caused by a type of fungus called Aspergillus (pronounced as·per·gil·us).

There are several types of aspergillosis:

Allergic Forms
Allergic Bronchopulmonary Aspergillosis (ABPA): An allergic reaction to the Aspergillus fungus causing lung inflammation.
Allergic Fungal Rhinosinusitis: An allergic reaction to fungi (often including Aspergillus) in the nasal passages and sinuses.
Severe Asthma with Fungal Sensitization (SAFS): A condition in which patients with severe asthma become sensitized to multiple fungi, with Aspergillus being the most common.

Infectious Forms
Aspergilloma: A condition in which a ball of Aspergillus grows in the lungs or sinuses.
Chronic Pulmonary Aspergillosis (CPA): A long-term Aspergillus infection of the lungs. It persists for at least three months.
Invasive Aspergillosis: This is the most serious form of the disease. In this condition, Aspergillus typically invades the lung (invasive pulmonary aspergillosis) or occasionally the sinuses and can spread to other organs. When Aspergillus infection involves many organs, it is called disseminated aspergillosis.
Cutaneous (Skin) Aspergillosis: A condition in which Aspergillus is present in the skin. It occurs when Aspergillus enters the body through a break in the skin or spreads to the skin from somewhere else in the body.

The Aspergillus fungus is everywhere. It is common both indoors and outdoors. We breathe in Aspergillus spores every day, but not every type of Aspergillus can make us sick. To learn more about the science of Aspergillus, see the Science Sidebar.

The Burden of Aspergillosis 

How common is aspergillosis? We don’t know exactly how many people are affected by aspergillosis, because it is not tracked very closely. The allergic forms are more common than invasive aspergillosis. Worldwide, experts estimate that 4.8 million people have the allergic form ABPA, and over 1.8 million people have the infectious form CPA. In the United States, about 15,000 hospitalizations were tied to aspergillosis in 2014, with these infections costing about 1.2 billion dollars.

1.8 million

Annual worldwide incidence of chronic pulmonary aspergillosis (CPA)

What is the prognosis for aspergillosis? Most of the mild, allergic forms of aspergillosis do not lead to death, but they can have serious negative impacts on the day-to-day activities of those with the disease. In contrast, the infectious forms, particularly invasive aspergillosis, while less common and typically seen in immunocompromised patients, can be deadly. Right now, the 1-year survival rate for an organ-transplant patient with invasive aspergillosis is 59%. For stem-cell transplant recipients, it’s 25%. Read on to learn about strategies to improve these outcomes.

Key Term:

Conidia are a type of spore formed by fungi. They are born on specialized stalks.

Genus is a category of an organism that is “above” a species and “below” a family in the organism’s taxonomic (organizational) system.

Prognosis is a forecast for the likely outcome of a disease. Some diseases have a poor prognosis (they are likely to lead to death or disability), while others have a good prognosis (affected individuals are likely to recover from the disease or its impact won’t be too bad).

Resistant is a condition in which an organism, such as a fungus, does not respond to drugs used to control it. Resistance can either be intrinsic (the organism was inherently able to escape the action of the drug) or acquired (the organism develops a means of overcoming or resisting the drug’s method of killing).

Spores are particles essential for the reproduction of fungi. You can think of fungal spores like plant seeds. For Aspergillus, the spores are called conidia.

Science Sidebar:

ASPERGILLUS: MORE ON THE MOLD

Aspergillus is a fungal genus. In print, a genus is usually italicized and written with an initial capital letter. It is often written in connection with a specific species, which is written in lowercase and italicized. Sometimes the genus is abbreviated to 1 letter (e.g., A. for Aspergillus).

There are more than several hundred Aspergillus species, but only a small number can cause human disease. Among Aspergillus species, fumigatus is the most common cause of human infection. Other species that can cause infection in humans include A. terreus, A. flavus, and A. niger. More recently, a hard-to-diagnose collection of Aspergillus fungi, called “cryptic” because they are elusive, has been identified. We are just learning more about these less common species, but we do know that they appear to be more resistant to traditional antifungal drugs than other Aspergillus spp. Cryptic Aspergillus species include A. tubigensis, A. tamarii, A. lentulus, and A. sydowii.

Aspergillus is a mold, which is a type of fungi that grows in the form of tubules that branch (called hyphae). When Aspergillus fungi are ready to reproduce, they disseminate through the form of spores (also called conidia). As shown in the image at the top of this page, when the Aspergillus fungus is ready to produce these spores, it develops a stalk-like structure off the hyphae that has a starburst-type structure at the end containing conidia. The person who first described Aspergillus was a biologist and priest. He thought the structure of Aspergillus looked like an aspergillum (from Latin aspergere meaning to scatter), a tool used to sprinkle holy water.