Aspergillosis is an infection caused by a type of mold (fungus). The illnesses resulting from aspergillosis infection usually affect the respiratory system, but their signs and severity vary greatly.

The mold that triggers the illnesses, aspergillus, is everywhere — indoors and outdoors. Most strains of this mold are harmless, but a few can cause serious illnesses when people with weakened immune systems, underlying lung disease or asthma inhale their fungal spores.

In some people, the spores trigger an allergic reaction. Other people develop mild to serious lung infections. The most serious form of aspergillosis — invasive aspergillosis — occurs when the infection spreads to blood vessels and beyond.

Depending on the type of aspergillosis, treatment may involve observation, antifungal medications or, in rare cases, surgery.

The signs and symptoms of aspergillosis vary with the type of illness you develop:

Allergic reaction

Some people with asthma or cystic fibrosis have an allergic reaction to aspergillus mold. Signs and symptoms of this condition, known as allergic bronchopulmonary aspergillosis, include:

Aspergilloma

Certain chronic lung (pulmonary) conditions, such as emphysema, tuberculosis or advanced sarcoidosis, can cause air spaces (cavities) to form in the lungs. When people with lung cavities are also infected with aspergillus, fungus fibers may find their way into the cavities and grow into tangled masses (fungus balls) known as aspergillomas.

Aspergillomas may produce no symptoms or cause only a mild cough at first. Over time and without treatment, however, aspergillomas can worsen the underlying chronic lung condition and possibly cause:

Invasive aspergillosis

This is the most severe form of aspergillosis. It occurs when the infection spreads rapidly from the lungs to the brain, heart, kidneys or skin. Invasive aspergillosis occurs only in people whose immune systems are weakened as a result of cancer chemotherapy, bone marrow transplantation or a disease of the immune system. Untreated, this form of aspergillosis may be fatal.

Signs and symptoms depend on which organs are affected, but in general, invasive aspergillosis can cause:

Other types of aspergillosis

Aspergillus can invade areas of your body other than your lungs, such as your sinuses. In your sinuses, the fungus can cause a stuffy nose sometimes accompanied by drainage that may contain blood. Fever, facial pain and headache may also occur.

If you have asthma or cystic fibrosis, see your doctor whenever you notice a change in your breathing. Although aspergillosis may not be the cause, it’s important to have breathing problems evaluated.

If you have a weakened immune system and develop an unexplained fever, shortness of breath or a cough that brings up blood, get immediate medical care. In the case of invasive aspergillosis, prompt treatment is crucial. In some cases, treatment with antifungal medication begins as soon as aspergillosis is suspected, even before testing has confirmed the diagnosis.

Aspergillus mold is unavoidable. Outdoors, it’s found in decaying leaves and compost and on plants, trees and grain crops.

Everyday exposure to aspergillus is rarely a problem for people with healthy immune systems. When mold spores are inhaled, immune system cells surround and destroy them. But people who have a weakened immune system from illness or immunosuppressant medications have fewer infection-fighting cells. This allows aspergillus to take hold, invading the lungs and, in the most serious cases, other parts of the body.

Aspergillosis is not contagious from person to person.

Your risk of developing aspergillosis depends on your overall health and the extent of your exposure to mold. In general, these factors make you more vulnerable to infection:

Depending on the type of infection, aspergillosis can cause a variety of serious complications:

It’s nearly impossible to avoid exposure to aspergillus, but if you have had a transplant or are undergoing chemotherapy, try to stay away from places where you’re likely to encounter mold, such as construction sites, compost piles and buildings that store grain. If you have a weakened immune system, your doctor may advise you to wear a face mask to avoid being exposed to aspergillus and other airborne infectious agents.

Diagnosing an aspergilloma or invasive aspergillosis can be difficult. Aspergillus is common in all environments but difficult to distinguish from certain other molds under the microscope. The symptoms of aspergillosis are also similar to those of other lung conditions such as tuberculosis.

Your doctor is likely to use one or more of the following tests to pinpoint the cause of your symptoms:

Aspergillosis treatments vary with the type of disease. Possible treatments include:

People who develop aspergillosis usually have an underlying condition, such as asthma or cystic fibrosis, or have a weakened immune system due to illness or to immune-suppressing medications. If you have symptoms of aspergillosis and are already being treated for a medical condition, call the doctor who provides your care for that condition. In some cases, when you call to set up an appointment, your doctor may recommend urgent medical care.

If you have a weakened immune system and develop an unexplained fever, shortness of breath or a cough that brings up blood, seek immediate medical care.

If you have time to prepare before seeing your doctor, here’s some information to help you get ready for your appointment.

What you can do

Prepare a list of questions so that you can make the most of your time with your doctor. For aspergillosis, some basic questions to ask your doctor include:

Don’t hesitate to ask other questions.

What to expect from your doctor

Your doctor is likely to ask you some questions, including:

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