Picture: Infectious mononucleosis (kissing disease) is a viral infection spread by saliva causing fever, fatigue, sore throat, and enlarged lymph nodes.
Infectious Mononucleosis

Infectious Mononucleosis (Mono)

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Infectious mononucleosis (mono) facts

  • Infectious mononucleosis (mono) is a contagious illness caused by the Epstein-Barr virus (EBV).
  • The infection can be spread by saliva, and the incubation period for mono is four to eight weeks.
  • Most adults have laboratory evidence (antibodies against the EBV) indicative of a previous infection with EBV and are immune to further infection.
  • The symptoms of mono include fever, fatigue, sore throat, and swollen lymph nodes.
  • The diagnosis of mono is confirmed by blood tests.
  • Mono can cause liver inflammation (hepatitis) and enlargement of the spleen.
  • People who have had mono can continue to shed virus particles in their saliva during reactivations of the viral infection throughout their lifetime.
  • Vigorous contact sports should be avoided in the illness and recovery phase to prevent rupture of the spleen.

What is infectious mononucleosis?

Infectious mononucleosis, "mono," "kissing disease," and glandular fever are all terms popularly used for the very common infection caused by the Epstein-Barr virus (EBV). EBV is a member of the herpesvirus family. The characteristic symptoms of infection with EBV include fever, fatigue, malaise, and sore throat. The designation "mononucleosis" refers to an increase in a particular type of white blood cells (lymphocytes) in the bloodstream relative to the other white blood cells as a result of the EBV infection.

The disease was first described in 1889 and was referred to as "Drüsenfieber," or glandular fever. The term infectious mononucleosis was first used in 1920 when an increased number of lymphocytes were found in the blood of a group of college students who had fever and symptoms of the condition.

Reviewed by William C. Shiel Jr., MD, FACP, FACR on 9/7/2011


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Could your sore throat be a symptom of mono?

Sore Throat: Is It Mono?

Medical Author: Melissa Conrad Stöppler, MD
Medical Editor: William C. Shiel Jr., MD, FACP, FACR

Having a sore throatcan be a symptom of many conditions, and many people wonder if their own sore throat might be a sign of something more serious than the common cold. Specifically, infectious mononucleosis ("mono") and infection with Streptococcus bacteria ("Strep throat") are two conditions that both produce an extremely painful sore throat.

Like the common cold, infectious mononucleosis is caused by a viral infection. The virus responsible for mono is called the Epstein-Barr virus, abbreviated EBV. EBV is a very common virus worldwide, and studies show that up to 95% of the U.S. population has been infected with EBV at some point in their lives. EBV infection, especially if it occurs early in childhood, does not always cause illness, or it may cause a very mild illness that is not distinguishable from colds or other mild illnesses of childhood. However, when infection first occurs during the teen years or in young adulthood, infectious mononucleosis will develop in up to 50% of cases.

Symptoms of mono include fatigue, sore throat, swollen lymph nodes, and fever. Enlargement of the spleen and inflammation of the liver may also occur. Severe complications are very rare, and the condition gradually resolves on its own. Since mono is caused a virus and not a bacteria, antibiotics are of no benefit. Therefore, treatment is directed at relieving the symptoms, which may persist for one to two months.

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