What is aspergillosis?
Aspergillosis is an infection or allergic reaction caused by various kinds of mold (a type of fungus). Mold is often found outdoors on plants, soil, or rotting vegetable matter. Mold can also grow indoors on household dust, food items such as ground spices, and building materials. Aspergillus fumigatus is the type of mold that is most likely to cause aspergillosis in certain people when they inhale (breathe in) its spores.
Who gets aspergillosis?
Exposure to Aspergillus is not likely to cause problems in the majority of people whose immune systems are healthy. However, people with chronic lung problems or people with weak immune systems may be at greater risk for developing the infection. People with weakened immune systems include those people taking chemotherapy or those who have had organ transplants.
Is there more than one type of aspergillosis?
There are several types of aspergillosis.
Pulmonary aspergillosis is most likely to develop in people who have chronic lung disorders or damaged lungs. These people are likely to have abnormal spaces in their lungs where the fungus can grow. The fungus can also rarely infect sinuses and ear canals. The mold spores can colonize (grow) inside lung cavities that developed as a result of chronic diseases, such tuberculosis, emphysema, or advanced sarcoidosis. The fibers of fungus might form a lump by combining with white blood cells and blood clots. This lump or ball of fungus is called an aspergilloma or mycetoma. In some cases, a fungus ball may be present in other organs of the body.
Invasive aspergillosis, the most severe type, occurs when the infection travels from the lungs into the bloodstream. Other organs, such as the kidneys, liver, skin or brain, may become infected. This is a very serious condition that may result in death if not treated. People with very weakened immune systems are more susceptible to invasive aspergillosis. Other risk factors include a low white blood cell count, long-term use of corticosteroids, or hospitalization.
Allergic bronchopulmonary aspergillosis (ABPA) is an allergic reaction that happens to some people after exposure to Aspergillus fungus. The fungus causes inflammation in the lungs and air passages. ABPA is more common in people with cystic fibrosis, bronchiectasis and/or asthma because they tend to have more mucus in their airways. Although it is unclear exactly why the allergic reaction occurs, the mucus in their airways may provide a good environment for the mold to grow. Unfortunately, the allergic reaction may produce symptoms similar to those associated with asthma, including wheezing, coughing and difficulty with breathing.
How common is aspergillosis?
It is estimated that up to 10% of people with cystic fibrosis or asthma experience an allergic reaction to aspergillus. ABPA is estimated to occur in about 2% of all asthmatics and in 2-15% of patients with cystic fibrosis.
Symptoms and Causes
What causes aspergillosis?
In most cases, aspergillosis is caused by a type of mold called Aspergillus fumigatus. Aspergillus mold can often be found on dead leaves, compost piles and other decaying vegetable matter, stored grain, and even foods and spices. The mold spores may be carried indoors on shoes and clothing and can grow on carpeting. Window unit air conditioners are susceptible to mold growth if filters are not kept clean, and water does not drain properly from the unit. Sites where buildings are being torn down or renovated may be contaminated with mold spores.
What are the symptoms of aspergillosis?
Symptoms can range from mild to severe, depending on the type of aspergillosis.
Pulmonary aspergillosis might not cause any symptoms, especially in the early stages. If the disease progresses, symptoms may include:
- Coughing, sometimes accompanied by mucus or blood.
- Chest pain.
- Difficulty breathing.
Symptoms of invasive aspergillosis may include:
- Breathing difficulties, such as shortness of breath.
- Kidney or liver failure.
- Bloody cough or massive bleeding from the lungs.
Allergic bronchopulmonary aspergillosis may cause:
- Coughing accompanied by mucus or blood.
- Wheezing or worsening of asthma.
- Increased mucus or sputum secretions.
- Inability to tolerate exercise or asthma brought on by exercise.
Many patients with asthma or cystic fibrosis already experience respiratory symptoms similar to those caused by an allergic reaction, so it may be difficult to detect ABPA in these situations. Sometimes, a worsening of symptoms such as coughing and wheezing is the only sign that the person is experiencing an allergic reaction.
If the allergic reaction recurs over time, and the lungs become inflamed repeatedly, damage to the lungs and central airways can occur. Recurrent allergic reactions may cause scarring of lung tissue and widening of the central airways, a condition known as bronchiectasis.
Diagnosis and Tests
How is aspergillosis diagnosed?
Your doctor will probably ask you about your medical history, including the type and duration of your symptoms and whether you have a cough or a fever. It may be difficult to diagnose the condition, because symptoms may resemble those of other diseases.
Some of the diagnostic tests that may be required include:
- Skin and blood tests: These tests are useful to diagnose ABPA, especially in cases where the patient has asthma, bronchiectasis or cystic fibrosis. The doctor or technician injects a small quantity of aspergillus antigen into the skin, usually the lower arm. A small red bump at or near the site will show that you have an allergic reaction. In addition, a sample of your blood might be analyzed to see if certain antibodies are present that indicate an allergic reaction.
- Imaging tests: A chest X-ray or computerized tomography scan (CT/CAT scan) may be performed to examine the lungs.
- Sputum culture: A sample of sputum might be stained (dyed) and tested to see if aspergillus fungus is present.
- Biopsy: A small sample of tissue is removed from the lungs or sinuses to diagnose invasive aspergillosis.
Management and Treatment
How is aspergillosis treated?
Treatment options include oral corticosteroids, antifungal medications, and surgery.
- Oral corticosteroid drugs: Solid or liquid oral medications may be prescribed to treat allergic bronchopulmonary aspergillosis. These drugs reduce inflammation and prevent respiratory symptoms, such as wheezing and coughing, from getting worse. Some of the most commonly used drugs are prednisone, prednisolone, and methylprednisolone.
- Antifungal drugs: These medications are generally used to treat invasive pulmonary aspergillosis. Voriconazole is currently the drug of choice because it causes fewer side effects and appears to be more effective than other medications. Amphotericin B or itraconazole are also effective in treating infection. Caspofungin is sometimes used in cases where the infection is resistant to the other antifungals. Antifungal drugs are sometimes used along with oral corticosteroids when treating ABPA. Antifungals can cause serious side effects, such as kidney and liver damage.
- Surgery: Surgery may be necessary in cases when aspergillomas are present and cause serious problems, such as excessive bleeding. Antifungal medications are usually not effective against aspergillomas, so surgery is recommended. Embolization may be an option to block blood flow to the artery supplying blood to the lung cavity where the fungus ball is located. This will stop the bleeding, but it may recur later.
How can aspergillosis be prevented?
Due to the prevalence of aspergillus mold in the environment, it is very difficult to avoid exposure. It is best to avoid locations with excessive amounts of dust or mold, such as construction sites or compost piles. People with weakened immune systems or mold allergies should avoid activities such as gardening or lawn mowing. If exposure to airborne dust or mold is likely, considering wearing a face mask or N95 mask. In some cases, your doctor might recommend the use of an antifungal medicine to prevent infection.