Author: Dr Marie Hartley, Staff Writer, 2010.
Aspergillosis is disease caused by aspergillus.
Aspergillus is a fungus (mould) that is found in abundance throughout the environment in soil, decomposing plant matter, ornamental plants, water, household dust, and building materials. More than 100 different species of aspergillus have been identified, but the species most commonly implicated in human disease are A fumigatus, A flavus, and A niger.
Most people breathe in aspergillus spores every day, with no ill-effect. However, in patients with pre-existing medical conditions, aspergillus can cause disease, primarily lung infection. Infection is more likely if a large number of spores are inhaled, such as exposure to a very dusty environment or building renovation.
Although aspergillus most commonly enters the human body via inhalation, on rare occasions the fungus may enter via the skin (primary cutaneous aspergillosis), particularly in patients with thermal burns or trauma. Occasionally outbreaks of primary cutaneous aspergillosis can occur due to contaminated biomedical equipment.
Aspergillus can also spread to the skin via the blood stream.
There are four common clinical patterns of disease.
|Pattern of disease||Clinical features||Population at risk|
|Acute invasive aspergillosis||
||People with severely impaired immunity, particularly those:|
||Can affect anyone, but more common in people with asthma or cystic fibrosis.|
||People with underlying cavity-causing lung disease, such as tuberculosis, emphysema, or cystic fibrosis.|
|Chronic necrotising (causing tissue death) pulmonary aspergillosis||
||People with mild immune impairment, such as underlying lung disease, alcoholism, or long-term corticosteroid therapy.|
Aspergillosis is more frequently dignosed as conditions producing impaired immunity become more prevalent. For example, invasive aspergillosis is estimated to occur in 5-13% of recipients of bone marrow transplants, 5-25% of patients who have received heart or lung transplants, and 10-20% of patients who are receiving intensive chemotherapy for leukaemia.
Skin changes most commonly occur as a consequence of widespread infection with Aspergillus in patients with impaired immunity.
Clinical features of primary cutaneous aspergillosis:
The term aspergillosis is not used to refer to chronic nail infections (onychomycosis) caused by aspergillus, which may affect people with normal immune systems.
Because this fungus is present everywhere throughout the environment it is virtually impossible to avoid it altogether. In patients with severely impaired immunity, the following measures may be helpful:
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