What is a Mononucleosis Spot Test?

Mononucleosis is often called the kissing disease. This is a viral infection transmitted through saliva and transferred through kissing. You can also be exposed through a cough, sneeze or by sharing a glass or food utensils with someone who has mononucleosis infection. But this is not as contagious as some infections such as the common cold.

You may be wondering what a mononucleosis spot is. If you are, this article is aimed at providing a precise answer to this question.

A mononucleosis spot is a test involving blood screening and is also known as the Paul-Bunnell test, Heterophile agglutination test, Heterophile antibody test or simply the mono spot test. This test is aimed at finding two antibodies that are present in blood both during and after being infected with the EBV virus that causes mono. The mono spot test is carried out along with a complete blood count (CBC). The CBC results provide doctors with information about the number of lymphocytes (white blood cells) and the appearance of abnormal cells in a patient's blood. 

How the Mono Spot Test is Performed

A doctor begins this test by collecting a blood sample from the fingertip or arm of the patient. The sequential order of testing activities in a fingertip is as follows:

• Cleansing of the hand using warm water and soap.
• Massaging the hand while avoiding direct contact with the puncture area.
• Puncture the skin around the middle finger using a lancet.
• The first blood drop to appear is wiped away.
• A capillary tube is used to collect a small amount of blood when placed on the puncture site.
• As the tube is removed, a cotton ball or gauze pad is placed on the puncture wound.

Blood is collected in a similar way as in the fingertips from the veins of the upper arm. The process of vein collection is:

• An elastic band is wrapped around the arm in order to obstruct the blood flow. This enlarges the veins and makes it easier to insert the needle into the vein.
• The needle is inserted into the vein after cleaning the site with an antiseptic like alcohol.
• The capillary tube is then attached to the needle to collect a sufficient amount of blood.
• The elastic band is unwrapped after the collection of blood.  
• Pressure is applied on the site and wrapped with a bandage.

The blood sample collected is then subjected to an antibody test for the Epstein-Barr virus (EBV). The collected blood sample is placed on a slide, mixed thoroughly with other suitable substances and then placed under a microscope. If the blood begins to clump (agglutination), a positive result for EBV is established.

Analysis of Obtained Results

The results that are obtained from a mononucleosis spot test can be either positive or negative. A positive result confirms the presence of a mono infection through heterophile antibodies. This is further supported by CBC results if the number of lymphocytes is elevated and reactive or abnormal ones are present. The false positive result may occur on a few specific occasions like if the individual has leukemia, rubella or hepatitis.

Negative mono spot test results are not so easily interpreted. These results require careful analysis and critical thinking before any meaningful conclusion can be reached. Three conclusions that could be made from a negative test result include:

1. The test was performed before antibodies are produced. This is often the case when the CBC results are positive and mono symptoms are present. It could also mean that the individual is one of the few patients that do not produce heterophile antibodies. A repeated mono spot test and administration of EBV-specific tests are usually recommended in this case to rule out or confirm the mono diagnosis.

2. Young children and infants produce no heterophile antibodies. Hence the mono test appears to be negative every time. Usually, this population displays no symptoms of mono and therefore the test could be avoided altogether.

3. The symptoms perceived as mono could be a result of another virus. This is most likely the case if reactive lymphocytes are absent and a negative mono spot test is observed. Other tests can be performed to find out the cause of the symptoms and these are very important for pregnant women to avoid complications to themselves and their babies. 

Risks Involved with Blood Collection

•    Swelling of veins may occur after the sample has been collected. Treatment with warm compressions several times per day can help reduce this symptom.

•    People with bleeding disorders may experience ongoing bleeding. Blood-thinning medications such as aspirin should also be avoided to decrease the chance of prolonged bleeding.

•    Bruises may form at the sample collection site.

•    Fainting or light-headedness may result from poor blood supply to the brain. 

The mononucleosis infection can spread through saliva and the incubation period is four to eight weeks. Using contaminated items such as drinking glasses or toothbrushes can spread the infection. Symptoms of mono include fever, fatigue, sore throat and swollen lymph nodes. A blood test can confirm the infection. Diagnosis of mono is confirmed by blood tests.

Complication of this infection could lead to liver inflammation (hepatitis) and enlargement of the spleen. Anemia, a condition which results in the decrease of red blood cells and hemoglobin can also occur. Platelet counts can come down. These are the blood cells which help in clotting. Inflammation of the heart muscle can also occur. Complications involving the nervous system such as meningitis may be a risk. During the illness and recovery period, vigorous contact should be avoided. Severe complications are rare till date. Vaccination to prevent hepatitis is also available.

The Epstein-Barr virus can cause much more serious illness in people who have impaired immune systems such as individuals with HIV/AIDS or people taking drugs to suppress immunity after an organ transplant.