Aspergillosis
Encyclopedia
Aspergillosis is the name given to a wide variety of diseases caused by fungi of the genus Aspergillus
. The most common forms are allergic bronchopulmonary aspergillosis
, pulmonary aspergilloma
and invasive aspergillosis. Most humans inhale Aspergillus spore
s 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. Conversely, it may also develop as an allergic response. The most common cause is Aspergillus fumigatus
.
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.
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.
and CT, pulmonary aspergillosis classically manifests as 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 stain
s, 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°.
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.
s 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.
Aspergillus
Aspergillus is a genus consisting of several hundred mold species found in various climates worldwide. Aspergillus was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli...
. The most common forms are allergic bronchopulmonary aspergillosis
Allergic bronchopulmonary aspergillosis
In medicine, allergic bronchopulmonary aspergillosis is a condition characterised by an exaggerated response of the immune system to the fungus Aspergillus . It occurs most often in patients with asthma or cystic fibrosis...
, pulmonary aspergilloma
Aspergilloma
An aspergilloma, also known as a mycetoma or fungus ball, is a clump of fungus which exists in a body cavity such as the lung. It is associated with the Aspergillus species, but Zygomycota and Fusarium may also form similar structures....
and invasive aspergillosis. Most humans inhale Aspergillus spore
Spore
In biology, a spore is a reproductive structure that is adapted for dispersal and surviving for extended periods of time in unfavorable conditions. Spores form part of the life cycles of many bacteria, plants, algae, fungi and some protozoa. According to scientist Dr...
s every day. Aspergillosis develops mainly in individuals who are immunocompromised
Immunodeficiency
Immunodeficiency is a state in which the immune system's ability to fight infectious disease is compromised or entirely absent. Immunodeficiency may also decrease cancer immunosurveillance. Most cases of immunodeficiency are acquired but some people are born with defects in their immune system,...
, either from disease or from immunosuppressive drugs, and is a leading cause of death in acute leukemia and hematopoietic stem cell transplantation. Conversely, it may also develop as an allergic response. The most common cause is Aspergillus fumigatus
Aspergillus fumigatus
Aspergillus fumigatus is a fungus of the genus Aspergillus, and is one of the most common Aspergillus species to cause disease in individuals with an immunodeficiency....
.
Symptoms
A fungus ballAspergilloma
An aspergilloma, also known as a mycetoma or fungus ball, is a clump of fungus which exists in a body cavity such as the lung. It is associated with the Aspergillus species, but Zygomycota and Fusarium may also form similar structures....
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
Liver failure
Acute liver failure is the appearance of severe complications rapidly after the first signs of liver disease , and indicates that the liver has sustained severe damage . The complications are hepatic encephalopathy and impaired protein synthesis...
(causing jaundice
Jaundice
Jaundice is a yellowish pigmentation of the skin, the conjunctival membranes over the sclerae , and other mucous membranes caused by hyperbilirubinemia . This hyperbilirubinemia subsequently causes increased levels of bilirubin in the extracellular fluid...
), 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.
In addition to the symptoms, an X-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...
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.
Diagnosis
On chest X-rayChest X-ray
In medicine, a chest radiograph, commonly called a chest X-ray , is a projection radiograph of the chest used to diagnose conditions affecting the chest, its contents, and nearby structures...
and CT, pulmonary aspergillosis classically manifests as an air crescent sign
Air crescent sign
In radiology, the air crescent sign is a finding on chest radiograph and computed tomography that is crescenteric and radiolucent, due to a lung cavity that is filled with air and has a round radiopaque mass. Classically, it is due to an aspergilloma, a form of aspergillosis, that occurs when the...
.
In hematologic patients with invasive aspergillosis, the galactomannan
Galactomannan
Galactomannans are polysaccharides consisting of a mannose backbone with galactose side groups Galactomannans are polysaccharides consisting of a mannose backbone with galactose side groups Galactomannans are polysaccharides consisting of a mannose backbone with galactose side groups (more...
test can make the diagnosis in a noninvasive way.
On microscopy
Microscopy
Microscopy is the technical field of using microscopes to view samples and objects that cannot be seen with the unaided eye...
, Aspergillus species are reliably demonstrated by silver stain
Silver stain
Silver staining is the use of silver to selectively alter the appearance of the target.-Use in medicine:It is used to stain histologic sections. This kind of staining is important especially to show proteins and DNA. It is used to show both substances inside and outside cells...
s, 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
Zygomycota
Zygomycota, or zygote fungi, is a phylum of fungi. The name comes from zygosporangia, where resistant spherical spores are formed during sexual reproduction. Approximately 1060 species are known. They are mostly terrestrial in habitat, living in soil or on decaying plant or animal material...
. Aspergillus hyphae tend to have dichotomous branching that is progressive and primarily at acute angles of about 45°.
Treatment
The current treatments include voriconazole and liposomal amphotericin B. Newer findings suggest use of mild oral steroids for a longer period of time, preferably for 6-9 months in aspergillosis in pulmonary segment.Other drugs used, such as amphotericin B
Amphotericin B
Amphotericin B is a polyene antifungal drug, often used intravenously for systemic fungal infections...
, caspofungin
Caspofungin
Caspofungin is an antifungal drug, the first of a new class termed the echinocandins from Merck & Co., Inc. It shows activity against infections with Aspergillus and Candida, and works by inhibiting the enzyme β-D-Glucan synthase and thereby disturbing the integrity of the fungal cell wall...
(in combination therapy only), flucytosine
Flucytosine
Flucytosine, or 5-fluorocytosine, a fluorinated pyrimidine analogue, is a synthetic antimycotic drug.It is structurally related to the cytostatic fluorouracil and to floxuridine. It is available in oral and in some countries also in injectable form. A common brand name is Ancobon. Flucytosine was...
(in combination therapy only) or itraconazole
Itraconazole
Itraconazole , invented in 1984, is a triazole antifungal agent that is prescribed to patients with fungal infections. The drug may be given orally or intravenously.-Medical uses:...
,
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. MallardMallard
The Mallard , or Wild Duck , is a dabbling duck which breeds throughout the temperate and subtropical Americas, Europe, Asia, and North Africa, and has been introduced to New Zealand and Australia....
s 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
Burley, Idaho
Burley is a city in Cassia and Minidoka counties in the southern portion of the U.S. state of Idaho. The population was 10,345 at the 2010 census. The city is the county seat of Cassia County....
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
Iowa
Iowa is a state located in the Midwestern United States, an area often referred to as the "American Heartland". It derives its name from the Ioway people, one of the many American Indian tribes that occupied the state at the time of European exploration. Iowa was a part of the French colony of New...
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.
External links
- USGS National Wildlife Health Center
- Aspergillus - Aspergillus website
- Aspergillosis at DoctorFungus.org
- News article in The GuardianThe GuardianThe Guardian, formerly known as The Manchester Guardian , is a British national daily newspaper in the Berliner format...