What is an aspergillus precipitin test?
Aspergillus precipitin is a laboratory test
performed on your blood. It’s ordered when a doctor suspects that you have an
infection caused by the fungus Aspergillus.
The test may also be called:
- aspergillus fumigatus 1
precipitin level test
- aspergillus antibody test
- aspergillus immunodiffusion test
- test for precipitating antibodies
Understanding aspergillus infection
Aspergillosis is a fungal infection caused by Aspergillus, a fungus
found in homes and outdoors. It’s most commonly found on stored grains, and
decaying vegetation such as dead leaves, stored grains, and compost piles. It
may also be found on marijuana leaves.
Most people breathe these spores every day without
getting sick. However, people who have weak immune systems are especially
vulnerable to fungal infections. This includes people with AIDS, HIV, or cancer
and those taking immune-suppressant treatments such as chemotherapy or transplant
There are two types of aspergillosis people
can get from this fungus.
Allergic bronchopulmonary aspergillosis (ABPA)
This condition causes allergic reactions such as wheezing and coughing, especially
in people who have asthma or cystic fibrosis. ABPA affects up to 11 percent of people who have cystic
Also called pulmonary aspergillosis, this infection can spread throughout the
body via the bloodstream. It can damage the lungs, kidneys, heart, brain, and
nervous system, especially in people with weak immune systems.
Symptoms of aspergillosis can vary. For
example, one person may have a dry cough, which is minor. However, another may
cough up large quantities of blood, which requires urgent medical care.
In general, aspergillosis symptoms include:
- shortness of breath
- wheezing in the chest
- dry cough
- coughing up blood
- weakness, fatigue, and a general
feeling of malaise
- unintentional weight loss
The symptoms of aspergillosis are similar to
those of cystic fibrosis and asthma. However, people with asthma and cystic
fibrosis who develop aspergillosis often get much sicker than people without
these conditions. They can experience worsening symptoms, such as:
- increased lung inflammation
- decline in lung function
- increased phlegm, or sputum, production
- increased wheezing and coughing
- increased asthma symptoms with
How the test works
Aspergillus precipitin detects the type and
quantity of specific Aspergillus antibodies in the blood. Antibodies are immunoglobulin
proteins made by the immune system in response to harmful substances called
antigens. An antigen is
a substance that your body recognizes as a threat. One example is an invading
microorganism such as Aspergillus.
Each antibody the immune system makes is
uniquely designed to defend the body against a specific antigen. There’s no
limit to the number of different antibodies a healthy immune system can make.
Each time the body encounters a new antigen it makes the corresponding antibody
to fight it.
There are five classes of immunoglobulin (Ig)
IgM and IgG are the most frequently tested.
These antibodies work together to protect the body against infections. IgE
antibodies are usually associated with allergies.
The aspergillus precipitin test looks for
IgM, IgG, and IgE antibodies in the blood. This helps to determine presence
of Aspergillus and how the fungus might be affecting the body.
procedure: Taking a blood sample
Your doctor will instruct you if there is a
need to fast before the blood test. Otherwise, no preparation is needed.
A nurse or other doctor will draw blood from
a vein, usually from the inside of the elbow. They will first clean the site
with a germ-killing antiseptic and then wrap an elastic band around the arm,
causing the vein to swell with blood.
They’ll gently insert a needle syringe into
the vein. Blood will collect in the syringe tube. When the tube is full, the
needle is removed.
The elastic band is then removed, and the
needle puncture site is covered with sterile gauze to stop bleeding.
Potential risks associated with a blood draw
It’s common to feel some pain when blood is
drawn. This may be only a slight sting or possibly moderate pain with some
throbbing after the needle has been removed.
Uncommon risks of blood tests are:
- excessive bleeding
- feeling lightheaded
- blood pooling under the skin, or hematoma
Interpreting the test results
Aspergillus precipitin test results are
usually available within one to two days.
A normal test result means that no Aspergillus antibodies
were found in your blood.
However, this doesn’t mean that Aspergillus is
entirely absent from your body. If you have received a normal test result but
your doctor still suspects your infection is caused by this fungus, a test
culture on sputum or a tissue biopsy may be needed.
An abnormal test result means that Aspergillus fungus
antibodies were found in your blood.
Following up after the test
You may improve on your own without treatment
if you have a healthy immune system.
People with weak immune systems may need to
take antifungal medications for three months to several years. This will help
rid your body of the fungus.
Any immunosuppressant drugs you are taking
may need to be stepped down or discontinued during treatment to help your body
fight the infection. Be sure to discuss this with your doctor.