Infectious Mononucleosis: Definition, Causes, Symptoms, Diagnosis, Treatment and Prevention

It is characterized by a triad of fever, pharyngitis, and lymphadenopathy.

It was initially described as glandular fever in 1889, but the term “infectious mononucleosis” was used later in 1920 to describe six college students who developed a febrile illness characterized by absolute lymphocytosis and the presence of atypical mononuclear cells in the blood.

The relationship between Epstein-Barr virus and infectious mononucleosis was established when a laboratory worker became infected with Epstein-Barr virus and developed infectious mononucleosis, as well as a recently positive heterophile test.

The Epstein-Barr virus is a widely spread herpes virus that is transmitted by intimate contact between an infected person and a susceptible person.

The Epstein-Barr virus has not been obtained from environmental sources, suggesting that humans are the main reservoir for the virus.

Antibodies to the Epstein-Barr virus have been demonstrated in all population groups, with a worldwide distribution; approximately 90 to 95 percent of adults are eventually seropositive for the Epstein-Barr virus.

Currently, the seroprevalence of Epstein-Barr virus is close to 100 percent in developing countries and ranges between 25 and 50 percent in the lowest socioeconomic groups in developed countries.

Many attribute this finding to intense personal contact and poor personal hygiene among children, which provide opportunities for the early acquisition and later spread of the Epstein-Barr virus.

Epstein-Barr virus acquired during childhood is often subclinical, with fewer than 10 percent of children developing a clinical infection despite high exposure rates.

The incidence of symptomatic infection begins to increase in adolescents into adulthood.

Extensive studies of infectious mononucleosis are now decades old, but traditionally the peak incidence of infection has been described in the age range of 15 to 24 years.

Some data suggest that cases of infectious mononucleosis may occur later in life with greater severity, requiring hospitalization.

Infectious mononucleosis is relatively rare in adults, accounting for less than 2 percent of pharyngitis in adults.

Causes of infectious mononucleosis

Infectious mononucleosis is caused by the Epstein-Barr virus. A milder form is caused by cytomegalovirus.

Both Epstein-Barr and cytomegalovirus are members of the herpes virus family.

Symptoms of infectious mononucleosis

Epstein-Barr is a very common virus. When children are infected with it, they often do not have any noticeable symptoms. But uninfected adolescents and young adults who come in contact with the virus can develop symptomatic infectious mononucleosis.

Even after the symptoms of infectious mononucleosis are gone, the Epstein-Barr virus will remain inactive in the throat and blood cells for the entire life of that person.

The virus can reactivate from time to time in saliva or blood. But it almost always causes no symptoms.

Symptoms generally appear 20 to 50 days after infection.

The severity of the symptoms varies greatly from one individual to another. Symptoms can be so mild that one can have mono without knowing it. In other cases, the symptoms may be severe enough to require hospitalization.

Common symptoms include:

  • Severe sore throat, a symptom that is almost always present and lasts between 6 and 10 days.
  • The throat can be very red, with white spots or pus on the tonsils.
  • A fever of 100-103 ° F (37.8 to 39.4 ° C), which is usually worse during the first week and seems to be worse at night.
  • Swollen and tender glands (lymph nodes) in the neck, which last up to a month after the patient feels well.
  • Fatigue.
  • Headaches.

Diagnosis of infectious mononucleosis

The doctor will perform a physical exam, which includes the throat and nodes.

Because the symptoms of infectious mononucleosis are similar to those of other infections, the doctor will try to determine if the symptoms are those of infectious mononucleosis, strep, or some other viral infection.

The doctor can perform various tests such as:

  • Take a sample from the back of the throat to order a culture.
  • Request a white blood cell count. The presence of certain types of white blood cells (atypical lymphocytes) can support the diagnosis.
  • Request a test for antibodies, these may be present in the blood in response to the Epstein-Barr virus as well as the cytomegalovirus.
  • Request a heterophile antibody test. This is the so-called monospot test. If it is positive, it may mean that the patient has infectious mononucleosis. But this test can be falsely positive if you really have another condition. Or it can be falsely negative even if you have the disease, so it is unreliable.

Blood tests for antibodies to infectious mononucleosis are generally not positive until symptoms have been present for a week or more.

Treatment of infectious mononucleosis

If streptococci are present, patients with infectious mononucleosis will be treated with an antibiotic.

If strep is absent and symptoms continue for 7-10 days, you should see your doctor for further testing.

Like the common cold, infectious mononucleosis is a viral infection with no cure. Antibiotics do not work as a treatment.

These self-care measures can be followed to make yourself feel better.


To remove pus from the tonsils and reduce a sore throat, it is recommended to gargle with a mixture with a teaspoon of salt or baking soda, dissolved in a glass of very hot water.

Over-the-counter medications, such as antiseptic liquid gargles or chloraseptic lozenges, may be given, or your doctor may prescribe a prescription for a gargle that reduces a sore throat and makes swallowing easier.


Apply a heating pad or warm washcloth to swollen glands in the neck to help relieve sensitivity.


Medications can be taken for fever, sore throat, headache, and body pain, such as ibuprofen or naproxen, which are available without a prescription.

The instructions on the packaging must be followed. Acetaminophen should be avoided due to possible inflammation of the liver that is sometimes associated with infectious mononucleosis.

In addition, the patient must take special care during recovery.

Avoid vigorous activities

Because infectious mononucleosis affects the entire lymphatic system, including the spleen (located under the lower left rib cage), vigorous activities, such as soccer, or activities such as jogging or running, should be avoided.

Contact sports should not be played until at least two weeks after the symptoms have disappeared. Mild exercises, such as walking or swimming, can be done as long as the activity does not increase fatigue.


Rest at least eight hours a night, and if it is urgent to attend classes or work, or if you feel capable, you should rest frequently during the day.


You need to eat small amounts of food frequently, especially if your appetite decreases.

Nutritional or complementary milk shakes or drinks between meals are a good choice, as are peanut butter, egg, and cheese snacks.

If you have a sore throat, it is important to blend foods or consume soups and lots of juices to make them easier to swallow.

Drink plenty of caffeine-free fluids to avoid dehydration.

Alcoholic beverages and drugs not prescribed by your doctor should be avoided for at least six weeks, due to possible liver inflammation.

Most of the symptoms will probably be felt during the first two weeks of infection. After this time, the patient should gradually improve.

The recovery process varies from person to person, so the patient should base his activities and check-ups on how he feels.


Infectious mononucleosis is usually spread by close contact from one person to another, hence the name “kissing disease.”

The infection is not highly contagious and generally does not spread between people in the same room.

As a precaution, you should avoid sharing glasses and kissing until your sore throat and other symptoms are gone for 4 to 6 weeks.

Make sure you cover your mouth when coughing and sneezing, and you should wash your hands frequently.