Aspergillosis - Definition and Overview

Aspergillosis is an infection or an allergic response caused by a fungus of the Aspergillus type. It may play a role in allergy, but is best known for causing serious pulmonary infections in immunocompromised patients, e.g. those on chemotherapy.

Causes, incidence, and risk factors

Aspergillosis is caused by a fungus (Aspergillus), which is commonly found growing on dead leaves, stored grain, compost piles, or in other decaying vegetation.

It causes illness in three ways:

• as an allergic reaction in people with asthma (pulmonary aspergillosis - allergic bronchopulmonary type)
• as a colonization and growth in an old healed lung cavity from previous disease (such as tuberculosis or lung abscess) where it produces a fungus ball called aspergilloma
• as an invasive infection with pneumonia that is spread to other parts of the body by the bloodstream (pulmonary aspergillosis - invasive type).

The invasive infection can affect the eye, causing blindness, and any other organ of the body, but especially the heart, lungs, brain, and kidneys. The third form occurs almost exclusively in people who are immunosuppressed because of cancer, AIDS, leukemia, organ transplants, high doses of corticosteroid drugs, chemotherapy, or other diseases that reduce the number of normal white blood cells.

Symptoms

Symptoms of allergic aspergillosis:

• Fever
• Malaise
• Coughing
• Coughing up blood or brownish mucous plugs
• Wheezing
• Weight loss
• Recurrent episodes of lung obstruction

Symptoms of invasive infection:

• Fever
• Chills
• Headaches
• Cough
• Shortness of breath
• Chest pain
• Increased sputum production, which may be bloody
• Bone pain
• Blood in the urine
• Decreased urine output
• Weight loss
• Symptoms involving specific organs
  • Brain: meningitis
  • Eye: blindness or visual impairment
  • Sinuses: sinusitis
  • Heart: endocarditis

Signs and tests

Aspergillosis is detected by:

• Abnormal chest X-ray or CT scan
• Sputum stain and culture showing Aspergillus
• Tissue biopsy (see bronchoscopy with transtracheal biopsy) for aspergillosis
• Aspergillus antigen skin test
• Aspergillosis precipitin antibody or galactomannan positivity
• Elevated serum total IgE (immunoglobulin)
• Peripheral eosinophilia with allergic disease

Treatment

The goal of treatment is to control symptomatic infection. A fungus ball usually does not require treatment unless bleeding into the lung tissue is associated with the infection; then, surgical excision is required.

Invasive aspergillosis is treated with several weeks of intravenous amphotericin B, an antifungal medication. Itraconazole can also be used, or its newer counterpart voriconazole.

Endocarditis caused by Aspergillus is treated by surgical removal of the infected heart valves and long-term amphotericin B therapy.

Allergic aspergillosis is treated with oral prednisone. Some people may benefit from allergy desensitization. Antifungal agents do not help people with allergic aspergillosis.

Prognosis

Gradual improvement is seen in patients with allergic aspergillosis. Invasive aspergillosis may resist drug treatment and progress to death. The underlying disease and immune status of a person with invasive aspergillosis will also affect the overall prognosis.

Complications

• Amphotericin B can cause kidney impairment and severely unpleasant side effects.
• Invasive lung disease can cause massive bleeding from the lung.

Prevention

Caution has to be taken by patients known to be immunosuppressed. Be cautious in the use of drugs that suppress the immune system. Prevention of AIDS prevents opportunistic diseases, including aspergillosis, that are associated with a damaged or incompetent immune system.

Source

• MedlinePlus article (http://www.nlm.nih.gov/medlineplus/ency/article/001326.htm)