Aspergillus Precipitin Test

MEANING OF ASPERGILLUS PRECIPITIN TEST

The Aspergillus precipitin test is a laboratory test that is performed on the blood. It is requested when the doctor suspects that the infection you have is caused by the fungus Aspergillus. This test is also called the Aspergillus fumigatus 1 precipitin level test or Aspergillus antibody test or aspergillus immunodiffusion test, or a test for precipitating antibodies.

aspergillus precipitin test
Photo Credit: ANDEB

KNOWING ABOUT ASPERGILLUS INFECTION

 Aspergillus is a fungal infection caused by Aspergillus, a type of fungus resident both at home and outdoors. It is mostly found on stored grains, and decaying vegetation such as dead leaves, stored grains, and compost materials. It can also be found on marijuana leaves. 

The spores of Aspergillus are inhaled daily without getting sick though those whose immune system has been weakened are susceptible to fungal infections. The immune system can be weakened by conditions such as AIDS, HIV, or cancer or those on immunosuppressive therapy such as chemotherapy or even those taking transplant anti-rejection drugs. This fungus can transmit two forms of aspergillosis.

ALLERGIC BRONCHOPULMONARY ASPERGILLOSIS

This form of aspergillus causes allergies which present with symptoms such as coughing and wheezing mostly in those with a preexisting lung condition such as asthma or cystic fibrosis. ABPA can affect up to 11 percent of those with cystic fibrosis.

INVASIVE ASPERGILLOSIS

It is also called pulmonary aspergillosis. It is an infection that spreads all through the body via the bloodstream. It can harm the lungs, kidneys, heart, brain, and nervous system, mostly in those with the weak immune system. 

The symptom of aspergillosis differs from person to person. Example, one individual with the condition may have a dry cough which is a mild presentation while another with the same condition may have cough productive of copious amounts of bloody sputum.

Generally, the symptoms of aspergillosis include the following:

  • Shortness of breath
  • Wheezing in the chest
  • Fever
  • Dry cough
  • Bloody sputum
  • Weakness, malaise, and fatigue
  • Weight loss

The symptoms of asthma and cystic fibrosis are similar to those of aspergillosis. This makes it hard to identify the exact cause of the symptoms as they may be masked.

If an individual who has cystic fibrosis or asthma also has aspergillosis, the symptoms would be much more severe than those who do not have cystic fibrosis or asthma. The symptoms would gradually worsen and include symptoms such as:

  • Worsening lung inflammation
  • A decrease in lung function
  • Increased production of phlegm or sputum
  • Increased coughing and wheezing
  • Worsening symptoms of asthma while exercising

HOW DOES THE TEST WORK

Aspergillus precipitin test determines the type and quantity of specific Aspergillus antibodies that are present in the blood. An antigen is a harmful substance that the body detects as a threat. An example of an antigen is the Aspergillus microorganism.

An antibody, on the other hand, is an immunoglobulin protein that is made by the immune system following an invasion by antigens.

Every antibody the immune system produces is specifically designed to protect the body against a particular antigen. The immune system can make as many antibodies as it wants to, depending on the antigen it encounters at every point in time.

There are 5 classes of immunoglobulin (Ig) antibodies and they include:

  • IgM
  • IgG
  • IgE
  • IgA
  • IgD

The warm and cold antibodies (IgM and IgG) are the most frequently tested antibodies. These antibodies function together to defend the body from every infection. IgE antibodies are strongly related to allergies.

The Aspergillus precipitin test checks for IgM, IgG, and IgE antibodies in the blood. This assists in determining the presence of Aspergillus and the way in which this fungus affects the body.

PROCEDURE FOR THE TEST

The test is conducted on a blood sample so the blood must first be drawn.

The healthcare provider will advise you to fast if there is any need to else no preparation would be done.

Blood is drawn from a vein, usually the vein at the cubital fossa in the elbow. The site is first disinfected with an antiseptic and then an elastic band or tourniquet is wrapped around the arm. This makes the vein to be filled with blood.

A needle is then inserted into the vein and blood collects in the tube of the syringe. When the tube is filled up or when the quantity of blood gotten is sufficient, the needle is removed.

The tourniquet is then removed and sterile gauze applied at the needle puncture site with a slight pressure to it to stop the bleeding.

RISKS ASSOCIATED WITH A BLOOD DRAW

Very minimal risks are associated with blood collection. The only risk might be a minor sting or moderate pain with a little throbbing after the needle has been removed.

The not so common risks of blood collection include:

  • Fainting
  • Excess bleeding
  • Feeling of lightheadedness
  • Blood accumulation underneath the skin called hematoma
  • Infection

INTERPRETATION OF THE TEST RESULTS

The results of the aspergillus precipitin test are usually ready within 1 to 2 days. The test result is said to be normal when there is an absence of Aspergillus antibodies in the blood but this does not mean that the Aspergillus is completely absent from the body. If there is still a strong suspicion that an infection is caused by Aspergillus irrespective of the fact that the test result came out as normal, further testing such as a sputum culture for the fungus or a tissue biopsy may be essential.

An abnormal test result is one in which Aspergillus antibodies have been found in the blood.

FOLLOW UP AFTER THE TEST

Those who have a strong and healthy immune system may heal without needing to take drugs.   

Those with a weakened immune system may have to take antifungal drugs for about 3 months to several years to help the body to completely remove the fungus. If you are taking any immunosuppressant drug, you may have to step down on the dosage or stop treatment to enable the body to fight infection. Ensure that you discuss this with the doctor.

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