Infectious Mononucleosis

"It is commonly known as "the kissing disease" since it is transmitted by direct contact with saliva".


Infectious mononucleosis is also known as Pfeiffer node fever or "kissing disease" because it is transmitted by direct contact with saliva.

Epstein Barr virus is the most common cause of infectious mononucleosis.

It is an acute, febrile, self-limiting infectious disease.

In most cases, infectious mononucleosis heals itself in 2-3 weeks.

In case of patients immunosuppressed by previous cellular immunodeficiency, bone marrow transplants, and solid organ transplants, Epstein-Barr virus can lead to Burkitt's tumor (especially in malaria endemic areas) or other lymphoproliferative syndromes (B lymphomas).

What are the symptoms of infectious mononucleosis?

The disease has an asymptomatic incubation period of 10-50 days.

It is followed by a prodromal period lasting 7-14 days with poor general condition, headache, asthenia, anorexia, myalgia, abdominal pain...

Sometimes the onset is abrupt or acute with high fever.

The most common symptoms are:

  • Fever, generally high.
  • Asthenia.
  • Swollen cervical, occipital lymph nodes, which are painful.
  • Pharyngo-tonsillitis.
  • Splenomegaly (enlarged spleen).
  • Anicteric hepatitis.

Do you have any of these symptoms?

You may have infectious mononucleosis

What causes infectious mononucleosis?

It is produced by a virus of the herpes-viridae family called Epstein-Barr virus, which is distributed worldwide.

It is transmitted mainly by oral secretions (saliva) through kissing or exchange of saliva, that is to say with a close personal contact, given its low contagiousness.

The virus is eliminated until 18 months after the primary infection, then it is eliminated intermittently throughout life (in the absence of clinical disease). Less frequently it can be transmitted by clinical transfusion.

Who can suffer from it?

It mainly affects school children, adolescents and young adults.

It is less frequent in preschool children (most of the infections in them are asymptomatic) and is rare in the first year of life.

The highest incidence is found between 4 and 12 years of age.

What are the complications?

The symptoms of the disease can last up to 2 or 4 weeks. The fever usually resolves in 2 weeks but sometimes lasts longer.

Asthenia persists, in some cases, for several weeks and splenomegaly for up to 3 months.

The complications are rare but they can appear the following ones and except for some, usually they evolve of benign form.

  • Neurological: meningitis, paralysis of cranial nerves, encephalitis...
  • Hematological: hemolytic anemia, thrombopenia (decreased platelets), granulocytopenia (decreased white cells).
  • Respiratory: pneumonia.
  • Spleen rupture: it is a serious but rare complication.
  • Hepatic (jaundice), renal (glomerulonephritis) and genital (orchitis).

How is infectious mononucleosis diagnosed?

<p>Laboratorio de extracciones</p>

The diagnosis of infectious mononucleosis (kissing disease) is made by the clinical picture and by the alterations in the blood: increase of leukocytes (white cells) being typical the lymphocytosis and the predominance of atypical lymphocytes.

There is a moderate elevation of transaminases in 50% of the patients.

Serological studies that demonstrate the presence of some antibodies (heterophile antibodies) and the study of specific antibodies for the Epstein-Barr virus (EBV) are also used.

These studies help to differentiate this disease from others that can be treated with a similar clinic, caused by other agents such as: cytomegalovirus, toxoplasma gondii, hepatitis virus, AIDS virus, etc.

How is infectious mononucleosis treated?

In general it is only necessary a symptomatic treatment with antipyretics, anti-inflammatories. In some cases the use of glucocorticoids can be useful.

In patients with bacterial superinfection faringoamigadalar can be used antibiotics but never ampicillins or amoxicillins (can trigger exanthema).

While the splenomegaly persists, the patient should avoid sports or other physical activities that involve risk of splenic rupture.

Where do we treat it?


The Infectious Diseases Service
of the Clínica Universidad de Navarra

This area works on the diagnosis and treatment of diseases produced by an infectious agent, which can be bacteria, virus, fungus and protozoa. Infections affect people by causing very different processes that can be located in any tissue of the human body, so it requires a specific approach.

This area carries out its activity on three fronts: care work, focused on the diagnosis and treatment of infectious diseases; teaching, with training of medical students, resident doctors and nurses; and research vocation, through the development of clinical and laboratory studies.

Organized in care units

  • Infections associated with biomaterials.
  • Nosocomial infections (multi-resistance).
  • Infections in immunosuppressed patients.
  • Community infection.
  • Traveler's medicine.
  • Prudent use and optimization program of anti-infective therapy.
  • Control of infection by multi-resistant microorganisms.
Imagen de la fachada de consultas de la sede en Pamplona de la Clínica Universidad de Navarra

Why at the Clinica?

  • We perform the traveler's assessment and analytical tests in less than 24 hours.
  • Second opinion consultation when the infection has not yet been resolved.
  • We ensure the prudent use of antibiotics.