Mononucleosis is a viral infectious disease, which is in some aspects similar to classic bacterial tonsillitis. It is a typical disease of adolescents, which is usually not serious, but it may cause some complications.


Mononucleosis is usually related to a virus known as Epstein-Barr virus (EBV). Similar symptoms may also be caused by cytomegalovirus (CMV), but CMV mononucleosis is much rarer. EBV virus occurs worldwide. It causes not only mononucleosis but in people with weakened immune system it also causes some types of tumors (e.g. tumors of the nasopharynx and Burkitt's lymphoma). In developed countries, the virus infects mostly well-nourished individuals with normally functioning immune system leading “only” to the mononucleosis.


The virus is present in saliva of the infected person and it usually spreads by kissing as it easily gets into the mouth and subsequently the nasopharynx of another person. Infectious mononucleosis is therefore also called the “kissing disease”. The EBV virus is very persistent and it usually stays in the body even after the acute symptoms disappear. The virus is dormant, but during a period of weakened immunity, it can reactivate and cause recurrence of infectious mononucleosis.


The symptoms are initially very similar to the classic streptococcal tonsillitis and that is a problem. The patient complains about fever, fatigue, malaise and inefficiency. Local troubles occur in the throat as the infected suffers from sore throat, enlarged reddish swollen tonsils with whitish coatings (that may cause troubles with swallowing) and painfully enlarged local lymph nodes. Infectious mononucleosis is a viral infection and antibiotics are completely useless. On the contrary, some antibiotics may be even harmful. The EBV virus reacts with aminopenicillins resulting in skin reactions that occur as an unpleasant red rash.


Infectious mononucleosis also affects liver and spleen. The liverand the spleen may be enlarged, rapid enlargement of the liver may cause an abdominal pain located in the right upper quadrant. Jaundice may occur due to disruption of liver metabolism, but it is a rare sign.


Symptoms of the disease, especially severe fatigue, may persist for several months and infectious mononucleosis requires patience.


The diagnosis depends on symptoms resembling tonsillitis, strong fatigue and laboratory signs of liver irritation (elevated liver tests) and specific changes in blood count. There is usually increased the number of lymphocytes and monocytes and decreased number of neutrophils. The diagnosis may be confirmed serologically by confirming the presence of antibodies against the EBV virus.


The modern medicine is still not very successful in treatment of the majority of viral infections and infectious mononucleosis is no exception. The only therapy is bed rest and adequate hydration. Painkillers may be used to quell the sore throat and non-steroidal anti-inflammatory drugs may be used against fever. The affected person should take diet with decreased intake of fats and avoid alcohol beverages. The patient should not take drugs containing paracetamol as it may further damage the irritated liver tissue.


Jiri Stefanek, MD  Author of texts: Jiri Stefanek, MD
 Sources: basic text sources