Allergic bronchopulmonary aspergillosis (ABPA) is a condition characterised by an exaggerated response of the
immune system
The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splint ...
(a
hypersensitivity response) to the
fungus
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from t ...
''
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. Viewing the fungi under a microscope, Mic ...
'' (most commonly ''
Aspergillus fumigatus''). It occurs most often in people with
asthma
Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, co ...
or
cystic fibrosis. ''Aspergillus''
spores are ubiquitous in soil and are commonly found in the
sputum of healthy individuals. ''A. fumigatus'' is responsible for a spectrum of lung diseases known as
aspergilloses.
ABPA causes
airway inflammation
Inflammation (from la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molec ...
, leading to
bronchiectasis—a condition marked by abnormal dilation of the airways. Left untreated, the
immune system
The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splint ...
and fungal spores can damage sensitive lung tissues and lead to scarring.
The exact criteria for the diagnosis of ABPA are not agreed upon.
Chest X-rays and
CT scans, raised blood levels of
IgE and
eosinophil
Eosinophils, sometimes called eosinophiles or, less commonly, acidophils, are a variety of white blood cells (WBCs) and one of the immune system components responsible for combating multicellular parasites and certain infections in vertebrates. A ...
s, immunological tests for ''Aspergillus'' together with sputum
staining and
sputum culture
A sputum culture is a test to detect and identify bacteria or fungi that infect the lungs or breathing passages. Sputum is a thick fluid produced in the lungs and in the adjacent airways. Normally, fresh morning sample is preferred for the bac ...
s can be useful. Treatment consists of
corticosteroids and
antifungal medications.
Signs and symptoms
Almost all patients have clinically diagnosed
asthma
Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, co ...
,
and present with
wheezing (usually episodic in nature),
cough
A cough is a sudden expulsion of air through the large breathing passages that can help clear them of fluids, irritants, foreign particles and microbes. As a protective reflex, coughing can be repetitive with the cough reflex following three ph ...
ing,
shortness of breath
Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing di ...
and
exercise intolerance (especially in patients with
cystic fibrosis).
Moderate and severe cases have symptoms suggestive of
bronchiectasis, in particular thick
sputum production (often containing brown
mucus plugs), as well as symptoms mirroring recurrent infection such as
pleuritic
Pleurisy, also known as pleuritis, is inflammation of the membranes that surround the lungs and line the chest cavity (pleurae). This can result in a sharp chest pain while breathing. Occasionally the pain may be a constant dull ache. Other sym ...
chest pain and
fever
Fever, also referred to as pyrexia, is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using val ...
. Patients with asthma and symptoms of ongoing infection, who do not respond to antibiotic treatment, should be suspected of ABPA.
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Pathophysiology
''Aspergillus'' spores are small (2–3 μm in diameter) and can penetrate deep into the respiratory system to the alveolar level.