|Classification and external resources|
Histopathologic image of pulmonary invasive aspergillosis in a patient with interstitial pneumonia. Autopsy material. Grocott's methenamine silver stain.
Aspergillosis is the name given to a wide variety of diseases caused by infection by fungi of the genus Aspergillus. The most common forms are allergic bronchopulmonary aspergillosis, pulmonary aspergilloma, and invasive aspergillosis. Most humans inhale Aspergillus spores every day.
Aspergillosis develops mainly in individuals who are immunocompromised, either from disease or from immunosuppressive drugs, and is a leading cause of death in acute leukemia and hematopoietic stem cell transplantation. The most common cause is Aspergillus fumigatus.
A fungus ball in the lungs may cause no symptoms and may be discovered only with a chest X-ray, or it may cause repeated coughing up of blood and occasionally severe, even fatal, bleeding. A rapidly invasive Aspergillus infection in the lungs often causes cough, fever, chest pain, and difficulty breathing.
Aspergillosis affecting the deeper tissues makes a person very ill. Symptoms include fever, chills, shock, delirium, and blood clots. The person may develop kidney failure, liver failure (causing jaundice), and breathing difficulties. Death can occur quickly.
Aspergillosis of the ear canal causes itching and occasionally pain. Fluid draining overnight from the ear may leave a stain on the pillow. Aspergillosis of the sinuses causes a feeling of congestion and sometimes pain or discharge. It can extend beyond the sinuses.
In addition to the symptoms, an X-ray or computerised tomography (CT) scan of the infected area provides clues for making the diagnosis. Whenever possible, a doctor sends a sample of infected material to a laboratory to confirm identification of the fungus.
On chest X-ray and CT, pulmonary aspergillosis classically manifests as a halo sign, and, later, an air crescent sign. In hematologic patients with invasive aspergillosis, the galactomannan test can make the diagnosis in a noninvasive way.
On microscopy, Aspergillus species are reliably demonstrated by silver stains, e.g., Gridley stain or Gomori methenamine-silver. These give the fungal walls a gray-black colour. The hyphae of Aspergillus species range in diameter from 2.5 to 4.5 µm. They have septate hyphae, but these are not always apparent, and in such cases they may be mistaken for Zygomycota. Aspergillus hyphae tend to have dichotomous branching that is progressive and primarily at acute angles of about 45°.
The current medical treatments for aggressive invasive Aspergillosis include voriconazole and liposomal amphotericin B. For the less aggressive allergic bronchopulmonary aspergillosis findings suggest the use of oral steroids for a prolonged period of time, preferably for 6–9 months in allergic aspergillosis of the lungs. Itraconizol is given with the steroids, as it is considered to have a "steroid sparing" effect, causing the steroids to be more effective, allowing a lower dose.,
Other drugs used, such as amphotericin B, caspofungin (in combination therapy only), flucytosine (in combination therapy only), or itraconazole, are used to treat this fungal infection. However, a growing proportion of infections are resistant to the triconazoles.
Infections in animals
Albeit relatively rare in humans, aspergillosis is a common and dangerous infection in birds, particularly in pet parrots. Mallards and other ducks are particularly susceptible, as they will often resort to poor food sources during bad weather. Captive raptors, such as falcons and hawks, are susceptible to this disease if they are kept in poor conditions and especially if they are fed pigeons, which are often carriers of "asper".
Aspergillosis has been the culprit in several recent rapid die-offs among waterfowl. From 8 December until 14 December 2006, over 2,000 Mallards died in the Burley, Idaho area, an agricultural community approximately 150 miles southeast of Boise. Moldy waste grain from the farmland and feedlots in the area is the suspected source. A similar aspergillosis outbreak caused by moldy grain killed 500 Mallards in Iowa in 2005.
While there is no connection between aspergillosis and the H5N1 strain of avian influenza (commonly called "bird flu"), rapid die-offs caused by aspergillosis can spark fears of bird flu outbreaks. Laboratory analysis is the only way to distinguish bird flu from aspergillosis.
- Primary cutaneous aspergillosis
- Black band disease, caused by a microbial consortium dominated by the cyanobacteria Phormidium corallyticum.
- White band disease The cause of this disease remains unknown.
- Brown band disease AKA Red band disease, probably caused by ciliates (possibly Helicostoma nonatum) and cyanobacteria.
- Yellow-band disease AKA Yellow blotch disease.
- Skeletal Eroding Band, caused by the ciliate Halofolliculina corallasia.
- White plague, caused by the bacterium Aurantimonas coralicida.
- Black necrosing syndrome AKA Dark spots disease, probably caused by a fungus.
- Rapid Wasting, possibly caused by a fungus growing on areas damaged by feeding action of the parrotfish Sparisoma viride.
- White pox disease, caused by the bacterium Serratia marcescens.
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- USGS National Wildlife Health Center
- Aspergillus - Aspergillus website
- Aspergillosis The National Aspergillosis Centre, UK
- Aspergillus The Aspergillus Website Blog
- Aspergillosis at DoctorFungus.org
- News article in The Guardian