Disease Fact Sheet Series:

What is infectious mononucleosis?
Infectious mononucleosis is an acute viral disease most commonly caused by the Epstein-Barr virus (EBV). It is not a reportable disease in Wisconsin and the number of cases is unknown.

Who gets infectious mononucleosis?
While most people are exposed to the Epstein-Barr virus sometime in their lives, as few as 50% will develop the symptoms of infectious mononucleosis. In developed countries such as the United States, the age of first exposure may be delayed until older childhood and young adulthood when symptoms are more likely to result. For this reason, it is recognized more often in high school and college students.

How is infectious mononucleosis spread?
The virus is spread by person-to-person contact, via saliva (on hands, toys, or by kissing).

What are the symptoms of infectious mononucleosis?
Symptoms include fever, sore throat, swollen glands, and fatigue. At times, the liver and spleen are affected and become enlarged. It takes several weeks for most people to recover, however it may take some people months to regain their normal level of activity. The disease is rarely fatal.

How soon do symptoms appear?
Symptoms appear from 4 to 6 weeks after exposure.

When and for how long is a person able to spread infectious mononucleosis?
Although the virus is present in the throat during the illness and over a year after infection, it is not known how long a person is able to spread after infection. Due to the presence of the virus in the blood, persons with infectious mononucleosis should not donate blood for six months after the onset of their illness.

What is the treatment for infectious mononucleosis?
No treatment other than rest is needed in the vast majority of cases. Due to the risk of rupture of the spleen, contact sports or heavy lifting should be avoided until a physician has cleared the patient to resume these activities.

What can a person do to minimize the spread of infectious mononucleosis?
Avoid activities involving the transfer of body fluids (commonly saliva) with someone who is currently or recently infected with the disease. At present, there is no vaccine available to prevent infectious mononucleosis.

For more information, contact your
Local Public Health Department

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Last Revised: June 22, 2011