Respiratory | Mononucleosis

Mononucleosis is predominantly caused by the Epstein-Barr virus and is diagnosed mostly in adolescents and young adults.

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Infectious mononucleosis, or mono in short form, is a contagious viral illness caused most frequently by the Epstein-Barr virus (EBV). EBV belongs to the herpes virus family and is responsible for most mononucleosis cases. Cytomegalovirus (CMV), another member of the herpes virus family, is responsible for causing about 8 percent of mono cases. Clinically, cases of mono caused by EBV are indistinguishable from those cases caused by CMV.


The incubation period for mononucleosis is about four to six weeks. The characteristic set of symptoms, commonly referred to as the clinical triad, includes:


  • Sore throat
  • Fever
  • Swollen lymph nodes


In addition, physical examination and laboratory analysis may reveal:


  • Fatigue
  • Malaise
  • Strep throat
  • Headache
  • Body aches
  • Rash
  • Mild hepatitis
  • Enlarged spleen
  • Atypical lymphocytosis
  • Heterophile antibody


Mono is most common in adolescents and young adults, although anyone of any age can get the infection.  EBV infects over 95 percent of the population worldwide. Some people carry the virus but do not develop signs and symptoms of mono. 

EBV and CMV, both responsible for causing mono, are highly contagious viruses. Mononucleosis is efficiently transmitted from one individual to another individual via saliva that may be spread through the sharing of utensils, cups or toothbrushes, as well as close contact from kissing. Mono is frequently referred to as “the kissing disease.”

The virus can also be transmitted through:

  • Sexual contact 
  • Droplets from a cough or sneeze
  • Blood transfusion
  • Organ transplantation

There is no vaccination to prevent contracting the viruses that cause mononucleosis. However, the most effective prevention of mono is to avoid kissing or sharing personal items with someone who is infected. Maintaining good health habits by eating nutritious foods and sleeping eight hours each night can improve the immune system’s response to infections or disease.

Mononucleosis is diagnosed based on well-characterized mono-like symptoms. The Monospot test is a blood test that can inform the presence of EBV by detecting heterophile antibodies.

The clinical course of mono is dependent on the age of the patient. Children often experience mild symptoms with primary EBV infection.  In contrast, college age patients are generally more symptomatic. For most patients, however, supportive care such as bed rest and hydration are the only therapies needed or recommended. The symptoms of most patients improve significantly within two to four weeks of time; although, some patients experience extended fatigue for a month or more.

While most patients experience complete recovery from mono, there are several noteworthy complications. Autoimmune hemolytic anemia may complicate about 3 percent of infected patients.1 Mild thrombocytopenia (low platelet count) and mild neutropenia (low white blood cell count) accompany mono infection. The enlargement of the spleen and subsequent splenic rupture is a rare but potentially deadly complication. Patients with infectious mononucleosis may be advised to avoid heavy lifting, contact sports, or other activities that could cause injury to the abdominal area.