Infectious Mononucleosis

Infectious Mononucleosis
Infectious mononucleosis is an acute disease due to infection by the Epstein-Barr virus (EBV) and characterized by the tetrad of fever pharyngitis, lymphocytosis and fatigue.

Primary EBV infection may occur during childhood, adolescence or adulthood.

Approximately 50% of all children, the infection is subclinical.

When this infection occurs in adolescents and adults, it may be either subclinical or it may be recognized as infectious mononucleosis.

Once infected with virus, persons remain asymptomatically infected for life, and the virus is shed intermittently from the oropharynx.

The route of transmission for this infection is, therefore by oropharyngeal contact (usually kissing) between an uninfected and a healthy EBV-seropositive individual who is asymptomatically shedding the virus.

The virus, after having been acquired first binds to and infects the nasopharyngeal cells and then the B-lymphocytes.

Circulating B-lymphocytes carry the virus throughout the body, producing a generalized infection of lymphoid tissues.

The activated B-cells stimulate the proliferation of specific killer T-cells, giving rise to an atypical lymphocytosis associated with primary EBV infection.

These killer T-lymphocytes destroy virally infected B-cells.

Another type of T-cells released are the suppressor T-cells which inhibit the B-cell production to immunoglobulins.

The onset of this disease is marked by malaise lasting from a few days to a week followed by fever, pharyngitis (which may be severe) and adenopathy.

In other cases, enlargement of a solitary lymph node or a group of nodes may be the sole clinical manifestation.

Splenomegaly due to hyperplasia of the red pulp is observed in about 50% of cases. Because of the risk of splenic rupture, heavy lifting and contact sports should be avoided for two months after presentation, even if there is no lasting splenomegaly.
Infectious Mononucleosis