Linda Crampton is an experienced teacher with a first-class honors degree in biology. She writes about the scientific basis of disease.
What Is Aspergillus?
Aspergillus is a genus of mold that can be found in many habitats around the world and exists as different species. Some species have important uses, but others can live on or in the human body and cause disease. The disease usually takes the form of a respiratory disorder and may be relatively minor. Unfortunately, in some people the mold becomes invasive and may cause a potentially dangerous infection. An infection produced by Aspergillus is known as aspergillosis.
Like other molds, Aspergillus is a type of fungus. Its body consists of thin, branching filaments called hyphae. The hyphae form a network called a mycelium. When they're mature, they produce reproductive spores that travel to other areas, where they germinate to produce new hyphae.
Aspergillus spores typically enter the human body by inhalation. If a person has a healthy immune system, the spores are generally destroyed. If the spores do manage to germinate, the resulting hyphae usually stay inside the airways and don't travel further into the body. In some people with a damaged immune system, however, the hyphae are able to invade deeper body structures and organs and may cause a very serious infection.
Some Helpful Species of Aspergillus
Although molds have a bad reputation, some species—including species of Aspergillus—can be helpful, at least under certain conditions. Some examples are listed below.
- Aspergillus niger produces citric acid, which is used in the processed food industry.
- Aspergillus oryzae plays an essential role in the production of the Japanese beverage known as sake.
- Aspergillus terreus produces useful industrial chemicals as well as lovastatin, a medication that lowers our blood cholesterol level.
Unfortunately, some mold species can be harmful for humans instead of helpful. In addition, some species can be helpful in certain situations and harmful in others.
Many species of Aspergillus exist. The mold usually grows in areas that have a good oxygen supply, such as on the surface of bread, on stored grain and dead leaves, and in compost and soil. Some species are helpful, some have no obvious effect on our lives, some are harmful, and some can be either helpful or harmful, depending on where they are growing.
In humans, Aspergillus may colonize skin wounds, the lungs, the sinuses, and parts of the body without a blood supply, such as the cornea of the eye and the ear canal. The fungus can also infect fingernails and toenails. Sometimes Aspergillus is present in internal organs, where it may cause serious health effects.
It’s hard for us to avoid the mold's spores. They are transported through the air and can be found in soil, air conditioning units, heating ducts, dust, water, and food. They may also be found in animal dung and bird droppings.
Aspergillus isn't dangerous for most of us, but it can interfere with some people's lives. The mold can make asthma worse, for example, and may make breathing difficult in people with certain medical conditions. In some people, an Aspergillus infection is very dangerous.
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The term "aspergillosis" refers to a spectrum of disorders. The mold often affects the lungs. Three important types of the disease are allergic bronchopulmonary aspergillosis (ABPA), chronic pulmonary aspergillosis (CPA), and invasive aspergillosis (IA), which is also called invasive pulmonary aspergillosis (IPA).
Allergic Bronchopulmonary Aspergillosis (ABPA)
Aspergillus spores may cause an allergic reaction in some asthmatics or in some people suffering from other respiratory system diseases, such as cystic fibrosis. The person's immune system overreacts to the presence of the spores, causing the airways to become inflamed. This condition is known as allergic bronchopulmonary aspergillosis, or ABPA. Until recently, the condition was thought to be rare, but today some researchers think that it may be more common than originally believed.
The spores of the mold may germinate in the respiratory system, causing hyphae to grow in the mucus of the airways. In ABPA, the fungal hyphae generally stay in the air passages and don't travel further into the body.
Symptoms of allergic bronchopulmonary aspergillosis may include increased and worsening asthma attacks and increased mucus production. The patient sometimes coughs up brown mucus and blood. (A doctor should always be consulted if these symptoms appear.) In severe cases, the person may also suffer from a fever, a headache, and weight loss and may feel generally unwell.
Doctors often prescribe corticosteroids to reduce the overactivity of the immune system and the inflammation, which can damage the lungs. Any mucus plugs in the air passages are removed. Antifungal medications may also be prescribed. This treatment usually relieves the symptoms of ABPA. However, there may be a flare-up of the infection and symptoms at a later date, which require more treatment.
Aspergillus produces specialized stalks called conidiophores. At the tip of a conidiophore is a ball containing spores. The spores are known as conidia. A conidium (a single spore) can produce hyphae once it lands in a suitable area. The video above shows a type of white blood cell known as a macrophage engulfing conidia.
Chronic Pulmonary Aspergillosis (CPA)
In chronic pulmonary aspergillosis, or CPA, Aspergillus is able to colonize areas in the respiratory system, producing a chronic (long lasting) condition. One area that may be colonized is a cavity that has formed in the lungs. Cavities form when lung tissue is destroyed by a disease such as tuberculosis.
An aspergilloma is a ball of fungal hyphae that develops inside a lung cavity. The aspergilloma is hidden from the immune system, except where it touches healthy lung tissue.
Chronic pulmonary aspergillosis usually affects people who have another chronic lung disease, a health problem such as alcoholism, or a weakened immune system. CPA may cause no symptoms, but the patient may cough up blood if blood vessels are damaged by the fungal growth. Other symptoms in addition to a cough may include breathlessness, chest pain, fatigue, and weight loss.
Patients with CPA are often treated with antifungal medications. Aspergillomas may be removed surgically.
Invasive aspergillosis is the most serious form of Aspergillus infection. An invasive infection may be very dangerous and requires intense treatment. This condition nearly always develops when the person’s immune system is severely weakened and isn't functioning well enough to destroy or limit the growth of the mold. The mold penetrates tissues from its initial infection site and enters organs. Tissues and organs that may be infected include blood and the liver, kidneys, heart, and brain. The infection may progress rapidly.
Possible Causes of the Invasive Condition
Conditions that might lead to the development of invasive aspergillosis include treatment by drugs that suppress the immune system after a person has received a transplant (immunosuppressive drugs), advanced AIDS, and long-term use of certain corticosteroids. Corticosteroids are useful medications for relieving inflammation, but some types may also suppress the activity of the immune system.
Neutrophils are white blood cells that can effectively fight fungi. Any condition that destroys neutrophils or prevents their formation increases the risk of developing invasive aspergillosis. Example of these conditions include some types of chemotherapy, high doses of chemotherapy drugs, leukemia, and radiation therapy applied to bones. Radiation may interfere with neutrophil production because it can damage the bone marrow cells that make the blood cells.
Potential Symptoms of the Condition
The symptoms described below may indicate the presence of another condition instead of aspergillosis. In addition, not all of the symptoms may appear and ones not mentioned may be experienced. A doctor's diagnosis is needed to identify the cause of any symptoms of ill health.
Symptoms of invasive aspergillosis may include chest pain, a bloody cough, shortness of breath, headache, fever, and chills. Some symptoms depend on the part of the body affected. Meningitis may be caused by fungal invasion of the brain, and endocarditis may develop after fungal invasion of the heart. If the kidneys are infected, there may be decreased urine production.
Some Possible Treatments
There are several types of antifungal drugs that doctors can prescribe for people suffering from invasive aspergillosis. Sometimes these drugs are given as a preventative measure when people receive transplants or medical treatments known to reduce the activity of the immune system. Medications in the azole group are often prescribed. Unfortunately, Aspergillus is becoming resistant to azoles.
In addition to the use of medicines, doctors try to find ways to reduce immunosuppression in patients who may develop invasive aspergillosis so that the patient’s immune system can help fight the fungus.
Researchers are exploring new strategies for helping people with apergillosis. The video above describes research at the University of Manchester that may be helpful in the fight against the disease.
Tips for Avoiding Aspergillosis
Most of us are constantly being exposed to Aspergillus spores, but they generally create no health problems. It’s still a good idea to reduce exposure to the fungus whenever possible, especially if we suffer from another health problem.
Some steps which should help are described below. Your doctor will likely have additional recommendations.
- Avoid damp areas and standing water.
- Stay away from compost and decaying plants.
- Reduce the humidity in buildings.
- Maintain clean heating ducts and air conditioners.
- Keep the dust level in buildings low.
- Use HEPA filters when ventilating enclosed areas and in devices such as vacuum cleaners. These filters remove fine particles from the air.
- Avoid gardening and mowing the lawn if you are at high risk for developing aspergillosis.
People with pre-existing medical conditions should follow their doctor's instructions carefully in order to avoid or reduce their exposure to Aspergillus spores. Doing so may enable a person to avoid a potentially nasty and sometimes dangerous illness.
- Information about the fungus and its effects from the Aspergillus website (which is run by the Fungal Infection Trust and the University of Manchester)
- Aspergillosis facts from the NHS (National Health Service)
- Aspergillosis information from the CDC (Centers for Disease Control and Prevention)
- Facts about the disease from the Mayo Clinic
This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.
© 2011 Linda Crampton
Linda Crampton (author) from British Columbia, Canada on April 05, 2018:
Thank you very much for the comment, Glenn. I've experienced problems after being in places with a musty smell, too. Environments with fungal spores can be very unpleasant.
Glenn Stok from Long Island, NY on April 05, 2018:
I once stayed in a hotel while traveling that had a musty smell and I had a really bad stuffy nose while there. Although I didn’t get sick, I guess my immune system was doing it’s job—as you explained.
Your article is very well written and informative, Linda. Now I realize that Aspergillus spores probably were airborne in that place.
Linda Crampton (author) from British Columbia, Canada on October 25, 2017:
Thank you for the comment, Syed.
syed burhan on October 25, 2017:
Linda Crampton (author) from British Columbia, Canada on February 02, 2012:
Thank you very much for the visit and the comment, davesnell!
davesnell from 5437 Cedarmint Drive, Charlotte, N.C. 28227 on February 01, 2012:
Its been a great to read such a quality hub. You have provided here a depth information on mold and possible health problems cause by them. Thanks for sharing
Linda Crampton (author) from British Columbia, Canada on May 07, 2011:
Susana, I sympathize with your mother’s problem, but I’m not a doctor. Your mother needs to follow her doctor’s advice, or seek help from another doctor. A fungal infection and low white blood cell count need to be dealt with professionally.
There are some things that your mother could do which will certainly be good for her general health – but remember that these steps are not specific treatments for her health problems.
Your mother – or anyone else - should follow a healthy and nutritious diet to support the immune system. The diet should include lots of vegetables, especially green, leafy vegetables, fruits, including citrus fruits and berries, whole grains, and a moderate amount of healthy fat. The diet should be low in saturated fat and contain no added sugar. Additional factors which are known to help the immune system function are exercising regularly, reducing stress and getting adequate sleep.
susana on May 07, 2011:
My mom has it.The ugly part is that her body's not producing
White blood cells, it eat up her ear drum, and nothing seems to
Work on her. Is there something
That you think it might help? Please help.
Linda Crampton (author) from British Columbia, Canada on March 31, 2011:
Hi, Nell. Yes, the effects of an Aspergillus infection can be horrible for some people. Thanks for the rating.
Nell Rose from England on March 31, 2011:
Hi, thanks for the info, I had absolutely no idea about this, it sounds horrible! rated up, I learn something new every day! lol
Linda Crampton (author) from British Columbia, Canada on March 26, 2011:
Thank you very much for the comment and the vote, kashmir56!
Thomas Silvia from Massachusetts on March 26, 2011:
Hi AliciaC, very interesting and informational hub !
Awesome and vote up !!!
Linda Crampton (author) from British Columbia, Canada on March 24, 2011:
Yes, most of us seem to have no problem with Aspergillus spores, it’s just some unlucky people that suffer from unpleasant effects. Thanks for commenting.
Kathi Mirto from Fennville on March 24, 2011:
I garden and compost all summer therefore I'm probably exposed quite a bit. Hasn't seemed to effect me, knock on wood! Good information to be aware of though, thank you for sharing!
Linda Crampton (author) from British Columbia, Canada on March 24, 2011:
Thank you very much, Chatkath.
Kathy from California on March 24, 2011:
Very very interesting, I had no idea. Thanks Alicia for an informative Hub - Well done!
Linda Crampton (author) from British Columbia, Canada on March 24, 2011:
Thanks for your comment, b. Malin!
b. Malin on March 24, 2011:
Wow, what a wonderful Hub on Aspergillosis Spores. All your tips are so good and practical, thanks for a very educational read.