Infectious Mononucleosis 101

Infectious mononucleosis, also known as mono, is most commonly found in teens and young adults.  But this infection that has been termed the “kissing disease” can infect anyone at any age.

What causes mono?

Mono is usually caused by the Epstein-Barr virus.  In fact, 90% of cases are caused by this.  This virus is a member of the herpes virus family and is extremely common throughout the world. (

How is it spread?

The virus that causes mono spreads through body fluids, most commonly through saliva.  If you share a toothbrush or utensils with a person who is infected, you can get the virus. The virus will last on an object until the object becomes totally dry.  Kissing and other sexual contact can also transmit it.

Once you get the virus in your body, it stays there.  It can be inactive for weeks and even months and you can be carrying it and spreading it to others.  When the virus does become active you begin to feel symptoms.

What are the symptoms?

Symptoms of mononucleosis include fatigue, fever, a sore throat and swollen lymph nodes.  Some people also experience an enlarged spleen and liver as well as a rash.  Fatigue is the symptom that most people begin to experience first and the one that lingers.

Once a person is infected, the symptoms can last anywhere from two to four weeks.  For some people, though, the symptoms can last longer.  And if you have a suppressed immune system the symptoms can return as the virus doesn’t ever leave the body.

How is it diagnosed?

Usually mono is diagnosed based on the symptoms and bloodwork isn’t always necessary.  However, bloodwork can show a general pattern including high white cell count, unusually shaped white blood cells, abnormal liver function results, and a lower number of neutrophils and platelets.

There is a test for the Epstein-Barr virus as well that looks for antibodies.  However, it’s important to know that as many as 95% of adults have been infected with this at some point in their lives.  So it is possible to test positive even if you don’t have symptoms or if your symptoms are caused by something else.

Is there a cure?

There is no cure for the Epstein-Barr virus.  Treatment includes managing symptoms by drinking plenty of fluids, resting, and taking medications to help reduce the fever and associated pain.

There is also no vaccine for Epstein-Barr making it difficult to completely prevent the infection from occurring.  However, there are things you can do to limit your exposure and prevent transmission.

For example, you can avoid sharing drinks and food with others who might be infected.  It’s also important to avoid sharing personal items such as toothbrushes.  You should also avoid kissing or sexual contact with someone who is infected.   However, this can be a challenge as someone can be carrying the virus without symptoms.

Mononucleosis is an illness that is uncomfortable, but generally will not cause problems long-term.  However, it is important to be treated so that you don’t experience complications such as dehydration or liver disease.

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