Aspergillosis

Causes and symptoms

Aspergillus is a fungus that is found almost everywhere, but particularly in soil, water, decaying vegetation, and stored grain. The fungus has also been cultured from ventilation systems and may be stirred up during building renovations. The species most commonly identified in patients with confirmed disease are A. fumigatus and A. flavus.

Airborne Aspergillus spores enter the body primarily through inhalation but can also lodge in the ear or eye. Normally functioning immune systems are generally able to cope without consequent development of aspergillosis.

It is important to make distinctions between the various forms of aspergillosis, as the treatment and prognosis varies considerably among types. Aspergillosis as a diagnosis refers to three general forms:

• Allergic bronchopulmonary aspergillosis (ABPA) is seen in patients with long-standing asthma, particularly in patients taking oral corticosteroids for a long period of time. This is usually the least serious and most treatable form.
• Aspergilloma refers to the mass formed when fungal spores settle into or colonize areas of the lung that have been pitted and scarred as a result of tuberculosis or prior pneumonia. There are several available treatments, although the success rate varies with each treatment.
• Invasive fungal infection refers to rare cases in which the fungus spreads throughout the body via the blood stream and invades other organ systems. Once established, invasive fungal infections are extremely difficult to cure and, as a result, the associated death rate is extremely high.

Aspergillus infection of the ear (called otomycosis), can produce itching and a discharge, sometimes noticed as a spot on the pillow. Fungal infection of the cornea of the eye in a susceptible person can result in blindness, if not diagnosed and treated promptly.

Diagnosis

Aspergillosis can be quite difficult to diagnose because the symptoms, such as coughing and wheezing, if present at all, are common to many respiratory disorders. Furthermore, blood and sputum cultures are not very helpful. The presence of Aspergillus is so common, even in asthmatics, that a positive culture alone is insufficient for a diagnosis. Other, potentially more useful, screening tools include examining the sample obtained after repeatedly washing the bronchial tubes of the lung with water (bronchial lavage), but examining a tissue sample (biopsy) is the most reliable diagnostic tool. Researchers are currently attempting to develop a practical,

specific, and rapid blood test that would confirm Aspergillus infection.

Signs of ABPA include a worsening of bronchial asthma accompanied by a low-grade fever. Brown flecks or clumps may be seen in the sputum. Pulmonary function tests may show decreased blood flow, suggesting an obstruction within the lungs. Elevated blood levels of an antibody produced in response to Aspergillus and of certain immune system cells may indicate a specific allergic-type immune system response.

A fungal mass (aspergilloma) in the lung usually does not produce clear symptoms and is generally diagnosed when seen on chest x rays. However, 70% or more of patients spit up blood from the lungs (hemoptysis) at least once, and this may become repetitive and serious. Hemoptysis, then, is another indication that the patient may be suffering from an aspergilloma.

In patients with lowered immune systems who are at risk for developing invasive aspergillosis, the physician may use a combination of blood culture with visual diagnostic techniques, such as computed tomography scans (CT) and radiography, to arrive at a likely diagnosis.

Content licensed from:

Author Info: Jill S. Lasker, The Gale Group Inc., Gale, Detroit, Gale Encyclopedia of Medicine, 2002

This feature is for informational purposes only and should not be used to replace the care and information received from your healthcare provider. Please consult a healthcare professional with any health concerns you may have.