Tuesday, July 15, 2008

Aspergillus and Aspergillosis - Part II

How is Aspergillus spread?

Since Aspergillus is so common in the environment, most people breathe in Aspergillus spores every day. It is probably impossible to completely avoid breathing in some Aspergillus spores. For people with healthy immune systems, this does not cause harm, and the immune system is able to get rid of the spores. But for people with compromised immune systems, breathing in Aspergillus spores, especially breathing in a lot of spores (such as in a very dusty environment) can lead to infection. Studies have shown that invasive aspergillosis can occur during building renovation or construction. Outbreaks of Aspergillus skin infections have been traced to contaminated biomedical devices.
What are the symptoms of aspergillosis?
There are many different kinds of aspergillosis, causing different symptoms. As mentioned above, ABPA can cause respiratory symptoms like wheezing, coughing and even fever in people with asthma or cystic fibrosis, and occasionally in people who are otherwise healthy. Aspergillus can also cause allergic sinusitis, and it can cause aspergilloma, or a “fungus ball” in the lung or other organs. Lung aspergillomas usually occur in people with other forms of lung disease, like emphysema or a history of tuberculosis. People with an aspergilloma in the lung may have no symptoms at all. Sometimes they may cough up bloody mucus. People who have invasive aspergillosis in the lung may have symptoms such as fever, chest pain, cough, and shortness of breath. Other symptoms may develop if the infection spreads beyond the lungs. When invasive aspergillosis spreads outside of the lungs, it can affect almost any organ in the body, including the brain.
How is an Aspergillus infection diagnosed?
Your doctor might perform a variety of tests to make the diagnosis. In addition to considering your risk factors, symptoms, and findings on physical examination, your doctor might ask you to have an imaging test performed, such as a chest x-ray or CT scan of the lungs. Also, samples of respiratory secretions or samples from affected tissues may be sent to the laboratory for fungal culture. Biopsies of affected tissue might be taken to look for evidence of the fungus under a microscope. There are other, newer tests that can help monitor for invasive aspergillosis in high-risk persons who are severely immunocompromised.

How can Aspergillus infections be prevented?
It is almost impossible to avoid all exposure to this fungus. It is present in the environment. However, for persons who are very immunocompromised, some measures that may be helpful include: avoidance of dusty environments and activities where dust exposure is likely (such as construction zones), wearing N95 masks when traveling near dusty environments, and avoidance of activities such as gardening and lawn work. Other air quality improvement measures such as HEPA filtration may be used in healthcare settings, and prophylactic antifungal medication may in some circumstances be prescribed by your doctor.


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