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Infectious Mononucleosis

Infectious mononucleosis (mono) is a common acute infectious disease usually found in adolescents and young adults. It is caused by the Epstein-Barr virus (EBV).

Classic symptoms of infectious mononucleosis are fever, sore throat, and swollen lymph glands. Sometimes, liver involvement may develop, causing nausea, vomiting, decreased appetite, abdominal pain, and/or yellowing of the skin or whites of the eyes (jaundice). A swollen spleen may cause abdominal pain and places the person at risk for splenic rupture, which requires emergency treatment. Heart problems or involvement of the central nervous system occur(s) only rarely, and infectious mononucleosis is almost never fatal. There are no known associations between active EBV infection and problems during pregnancy, such as miscarriages or birth defects. Although the symptoms of infectious mononucleosis usually resolve in 1-2 months and rarely last more than four months, EBV remains latent in a few cells in the throat, blood, and immune system for the rest of the person’s life. This dormancy is characteristic of all herpes viruses. Periodically, the virus can reactivate and is commonly found in the saliva of infected persons. This reactivation usually occurs without symptoms of illness.

Diagnosis is confirmed by blood test(s). Test results include an elevated white blood cell (WBC) count, an increased percentage of certain typical WBC’s, and a positive “mono spot” (antibody) test. The mono spot test has about a 10-15% false negative rate, but these occur primarily in children under ten. Your physician may wish to repeat the test in a week or so. When the test is repeatably negative, a person with a mononucleosis-like illness may have cytomegalovirus, adenovirus, or toxoplasmosis infection. These tests may not be positive until several weeks after the symptoms arise and, rarely, may remain negative throughout the course of the disease.

There is no antiviral medication or vaccine available. Treatment is symptomatic and supportive, but medical supervision is absolutely necessary. Patients are instructed to:

The acute phase generally lasts 1-2 weeks; at the end of that time, normal stamina is regained to about 90%. Full recovery may take 1-2 months, possibly longer.

Bed rest, while recommended for those suffering from the disease, has been found to lose its efficacy if prolonged excessively. In one study, a group of students allowed normal activity as soon as they felt like it appeared to recuperate faster than a group confined to bed until all signs of the illness were gone.

Contact the Dial-A-Nurse at 333-2700, or seek medical attention if severe abdominal pain, excessive vomiting, decreased mental status and/or confusion, dizziness upon standing or dark urine develop.

Mono is passed directly from person to person by contact with saliva. Do not share eating or drinking utensils or toothbrush. Practice good handwashing before food preparation, eating and after bathroom use.

National Center for Infectious Diseases

If you are a registered University of Illinois student and you have questions or concerns,
or need to make an appointment, please call: Dial-A-Nurse at 333-2700


If you are concerned about any difference in your treatment plan and the information in this handout,

you are advised to contact your health care provider.


Visit the McKinley Health Center Web site at:

HEd. II-002

© The Board of Trustees of the University of Illinois, 2007.



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