What is an Aspergillosis Precipitin Test?
Aspergillosis precipitin is a laboratory test performed on a patient’s blood. It is ordered when a doctor suspects that you have an infection that could be caused by the fungus Aspergillus.
The test may also be called Aspergillosis fumigatus 1 precipitin level test, Aspergillosis antibody test, Aspergillosis immunodiffusion test, and test for precipitating antibodies.
Understanding the Aspergillosis Infection
Aspergillosis is a fungal infection caused by Aspergillus, a fungus found in homes and outdoors. It is most commonly found on dead leaves, stored grains, compost piles, and other decaying vegetation. It may also be found on marijuana leaves.
Most people breathe these spores every day without getting sick. However, there are two types of aspergillosis people can get from this fungus:
- Allergic bronchopulmonary aspergillosis (ABPA) causes allergic reactions such as wheezing and coughing—especially in people who have asthma or cystic fibrosis. According to the Cystic Fibrosis Foundation, ABPA affects up to 11 percent of people who have cystic fibrosis (CFF).
- Invasive aspergillosis, also called pulmonary aspergillosis, 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.
People who have weak immune systems—such as people with AIDS, HIV, or cancer and those taking immune-suppressant treatments such as chemotherapy or transplant anti-rejection drugs—are especially vulnerable to fungal infections.
Symptoms of aspergillosis can vary. For example, one patient 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 (CF) and asthma. However, CF and asthma patients who have aspergillosis often get sicker and can experience these worsening symptoms:
- increased lung inflammation
- decline in lung function
- increased phlegm (sputum) production
- increased wheezing and coughing
- increased asthma symptoms with exercise
How the Test Works
Aspergillosis 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, for example, an invading microorganism such as Aspergillus.
Each antibody the immune system makes is uniquely designed to defend the body against a specific antigen. There is 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) antibodies: IgM, IgG, IgE, IgA, and IgD. The first two—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 aspergillosis precipitin test looks for IgM, IgG, and IgE antibodies in the blood. This helps to determine not only the presence of Aspergillus, but also how it the fungus might be affecting the body.
The 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 healthcare provider will draw blood from a vein, usually from the inside of the elbow. He or she 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.
The nurse will 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 is 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, fainting (or feeling light-headed), hematoma (blood pooling under the skin), and infection (a slight risk any time the skin is broken).
Interpreting the Test Results
Aspergillosis 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 get well on your own without treatment if you have a healthy immune system.
However, 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 physician.