Symptoms, Statistics , Etiology, and Diagnostic Tests

Symptoms and Statistics

Mononucleosis is a viral infection caused by Epstein-Barr virus (EBV). This disease is common in children and adolescents. Typical symptoms of mononucleosis are fever, pharyngitis, swollen lymph nodes, atypical lymphocytosis, enlarged spleen, sore throat, and fatigue (Ebell). Most young children are asymptomatic whereas symptoms are more pronounced in young adults (Chamberlain). Mononucleosis has the highest rates of incidence in young adults between ages fifteen and twenty five. The incidence rates range from eleven to forty eight cases per one thousand persons. The incidence rate in people younger than ten years old and older than thirty years old is less than one case per one thousand people (Ebell).

Picture retrieved from www.medicinenet.com

Etiology 

EBV is a virus that replicates in beta lymphocytes. The incubation period for EBV is around four to eight weeks. EBV invades beta lymphocytes by means of their CD21 receptors and within eighteen to twenty four hours the EBV antigens are detectable. The infected beta lymphocytes spread the disease throughout the reticuloendothelial system (liver, spleen, peripheral lymph nodes). EBV initiates beta lymphocyte proliferation and immortalization causing the lymphocytes to become antibody-producing plasma cells. Some of the antibody-producing plasma cells produce antibodies that react with EBV antigens and some do not. During the acute phase, twenty percent of circulating beta lymphocytes will produce EBV antigens (Chamberlain).

Diagnosis

Diagnosis of mononucleosis involves the detection of atypical lymphocytes in peripheral blood smears. During acute mononucleosis, the number of lymphocytes increases around sixty percent in the peripheral blood. Of those lymphocytes, around ten percent are atypical lymphocytes. The presence of atypical lymphocytes in the blood is the earliest indication of mononucleosis infection. As previously mentioned, EBV causes beta lymphocytes to produce antibodies called immunoglobin. Some of these plasma cells multiple and produce immunoglobin M (IgM) which does not react with EBV antigens but does react with antigens on sheep. IgM antibodies are then called heterophile antibodies because they react with something other than the EBV antigens. The heterophile antibodies are greatest in number during the first four weeks of infection. Heterophile antibody tests are used to detect the heterophiles antibodies. If heterophiles antibodies cannot detected, blood testing for specific EBV antibodies can be conducted (Chamberlain).

This table is an example of the table used when conducting the blood test that tests for specific EBV antibodies. Picture retrieved from Chamberlain.