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Mononucleosis

Definition

Mononucleosis is a viral infection causing fevers, sore throat, and swollen lymph glands, especially in the neck. It is typically caused by the Epstein-Barr virus (EBV), but can also be caused by other organisms such as cytomegalovirus (CMV). Both viruses are members of the herpesvirus family.

Causes, incidence, and risk factors

Mononucleosis is often transmitted by saliva. While it is known as "the kissing disease," occurring most often in 15- to 17-year-olds, the infection may occur at any age.

Mono may begin slowly with fatigue, malaise, headache, and sore throat. The sore throat becomes progressively worse, often with enlarged tonsils covered with a whitish-yellow covering. The lymph nodes in the neck are frequently enlarged and painful.

A pink, measles-like rash can occur and is more likely if the patient is given ampicillin or amoxicillin for a throat infection. (Antibiotics should NOT be given without a positive strep test.) The symptoms of mono gradually subside on their own over a period of weeks to months.

Chronic EBV infection may be associated with some rarer types of cancer. In Africa, for example, EBV is associated with Burkitt's lymphoma. In organ transplant patients, it can cause post-transplant lymphoproliferative disease (PTLD), a type of lymphoma.

Symptoms

fever
sore throat
enlarged lymph nodes, especially in the neck and armpit
general discomfort, uneasiness, or ill feeling
drowsiness
loss of appetite
muscle aches or stiffness
enlarged spleen
rash

Less frequently occurring symptoms include:

Signs and tests

During a physical examination, the doctor may find enlarged lymph nodes in the front and back of the neck, as well as swollen tonsils with the whitish covering. The doctor might also find an enlarged liver or enlarged spleen when pushing on your belly. There may be a skin rash present.

Laboratory findings often include an elevated white blood cell count, and the characteristic finding of atypical lymphocytes -- unusual-appearing white blood cells that are seen when blood is examined under a microscope. Abnormal liver function tests are also characteristic.

Common tests for EB include:

A monospot test (positive for infectious mononucleosis)
Epstein-Barr virus antigen by immunofluorescence (positive for EBV)
Epstein-Barr virus antibody titers can help distinguish acute infection from past infection with EBV

Treatment

Most patients recover within 2-4 weeks without medication. Younger children often don't have symptoms, while some older patients may have fatigue for up to 6 weeks.

There is no specific treatment available. Antiviral medications do not help. Steroid medication may be considered for patients with severe symptoms.

To relieve typical symptoms:

Take acetaminophen or ibuprofen for pain and fever.
Gargle with warm salt water for sore throat.
Get plenty of rest. Drink plenty of fluids.
Avoid contact sports while the spleen is enlarged (to prevent it from rupturing).

Expectations (prognosis)

The fever usually drops in 10 days, and swollen lymph glands and spleen heal in 4 weeks. Fatigue usually resolves within a few weeks, but may linger for 2 to 3 months.

Complications

Secondary bacterial throat infection
Rupture of spleen (this is rare; avoid pressure on the spleen)
Neurological complications (these are rare, but include meningitis, seizures, ataxia, Guillain-Barre syndrome, and Bell's palsy)
Hepatitis with jaundice (more common in patients older than 35)
Hemolytic anemia
Orchitis
Death in immunocompromised individuals

Calling your health care provider

The initial symptoms of mono feel very much like a typical viral illness. It is not necessary to contact a health care provider unless symptoms last longer than 10 days or you develop the following:

Severe sore throat or swollen tonsils
Difficulty breathing
Abdominal pain
Severe headache
Persistent high fevers (more than 101.5°F)
Yellow discoloration of your eyes or skin
Weakness in the arm or legs

Call 911 or go to an emergency room if you develop:

Sharp, sudden, severe abdominal pain
Significant difficulty swallowing or breathing
A stiff neck or severe weakness

Prevention

The infection is probably spread by saliva and close contact. People may be contagious while they have symptoms and for up to a few months afterwards. The virus can live for several hours outside the body. Avoid kissing or sharing utensils if you or someone close to you has mono. The exact period that people are contagious varies.

References

Hoffman, R., ed. Hematology: Basic Principles and Practice. 4^th Ed. New York, NY: Churchill Livingstone, 2005.

Gershon, AA, Hotez, PJ, and Katz, SL, eds. Krugman’s Infectious Diseases of Children. 11^th ed. St. Louis, MO: Mosby; 2004.

Noble J, ed. Textbook of Primary Care Medicine. 3^rd Ed. St. Louis, MO: Mosby; 2001.