Aspergillus Mold, Aspergillosis and Health

Aspergillus is a type of mold fungus that can be found in various habitats around the world. Its body consists of thin, branching filaments called hyphae. When they are mature, the hyphae produce reproductive spores that travel to other areas, where they germinate to produce new hyphae.

Some species of Aspergillus can live on or in the human body. If a person has a functioning immune system Aspergillus spores that enter the body are destroyed, or if the spores do manage to germinate the resulting hyphae stay inside body cavities or remain on the body surface. In some people with a damaged immune system, however, the hyphae are able to invade deeper body structures and organs, causing a more serious infection. Infection by Aspergillus is called aspergillosis. Three types of aspergillosis in humans are Allergic Bronchopulmonary Aspergillosis, Chronic Pulmonary Aspergillosis and Invasive Aspergillosis.

There are many species of Aspergillus. The mold usually grows in areas which have a good oxygen supply, such as on the surface of bread, on stored grain and dead leaves, and in compost.

In humans, Aspergillus may colonize skin wounds, the lungs, the sinuses and parts of the body without blood supply, such as the cornea of the eye and the ear canal. The fungus may also infect fingernails and toenails. Sometimes Aspergillus is present in internal organs, causing serious health effects.

It’s hard for us to avoid Aspergillus 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 spores usually enter the body by inhalation. They may cause an allergic reaction in some asthmatics or in some people suffering from other respiratory system diseases, such as cystic fibrosis. The spores germinate in the respiratory system, causing hyphae to grow in the airways. In ABPA the fungal hyphae stay in the air passages and don't travel further into the body.

In sensitive people, Aspergillus triggers the immune system to overreact to the presence of the fungus, resulting in the allergic reaction. The airways become inflamed. Symptoms may include increased and worsening asthma attacks and increased mucus production. The patient sometimes coughs up brown mucus and blood. In severe cases, the person may also suffer from a fever, a headache and weight loss and may feel generally unwell.

Doctors 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. The fungus infection is not cured by the antifungal medicine but it is reduced. 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.

Until recently, ABPA was thought to be a rare condition, but today some researchers think that it may be more common than originally believed.

In chronic pulmonary aspergillosis, Aspergillus is able to colonize areas in the respiratory system, including the airways (producing chronic necrotizing aspergillosis, or CNA) or inside the lungs (producing an aspergilloma).

CNA in the airways usually affects people that have another chronic lung disease, a health problem such as alcoholism or a weakened immune system. The infection progresses slowly, and tissues in the airways are damaged and destroyed.

An aspergilloma is a ball of fungal hyphae which develops inside a lung cavity that was created when tissue was destroyed by a previous disease, such as tuberculosis. The fungus in the cavity is hidden from the immune system, except when it touches healthy lung tissue.

Chronic pulmonary aspergillosis may cause no symptoms, but the patient may cough up blood if blood vessels are damaged by the fungal growth. Other symptoms include a cough, breathlessness, chest pain, fatigue and weight loss.

Patients with CPA may require treatment with antifungal medications. Aspergillomas can be removed surgically.

Invasive Aspergillosis is the most serious form of Aspergillus infection. An invasive Aspergillus infection is 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 often progresses rapidly.

Conditions which 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 corticosteroids.

Neutrophils are white blood cells that effectively fight fungi. Any condition that destroys neutrophils 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, since the bone marrow makes the blood cells.

Symptoms of invasive aspergillosis include chest pain, a very 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.

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 develop invasive aspergillosis so that the patient’s immune system can help fight the fungus.

Most of us are constantly being exposed to Aspergillus spores, but the spores generally create no health problems. It’s still a good idea to reduce exposure to the fungus whenever possible. Some steps which will help are to avoid damp areas, standing water, compost and decaying plants. Reduce the humidity in buildings. Maintain clean heating ducts and air conditioners, and keep the dust level in buildings low. Use HEPA filters to clean air and ventilate enclosed areas.