What is infectious mononucleosis?

Infectious mononucleosis (also called mono) is a viral infection that frequently affects young people. It is a common infection, but often it causes no symptoms, especially when children have it. However, for adolescents and young adults it is a frequent cause of illness and missed school.

How does it occur?

The virus that causes infectious mono is called EBV (Epstein-Barr virus). It is spread mainly through saliva, which is why it has the nickname 'kissing disease.'

What are the symptoms?

After the virus enters the body it can take up to a month before symptoms begin. The first symptoms usually include tiredness, fever, headache, and muscle aches. Many people have extreme tiredness and need to sleep 12 to 16 hours a day before they have any other symptoms. After just a few days of the fever and aches, the throat becomes sore and the lymph nodes (glands) in the neck get bigger.

Other common symptoms are loss of appetite, nausea, joint aches, rash, and vague abdominal fullness or pain.

How is it diagnosed?

Your health care provider will ask about your symptoms and then examine you. He or she will look for fever; a red throat with enlarged tonsils, sometimes covered with pus; and enlarged lymph nodes in the neck. You may also have a red rash, especially on the chest, and an enlarged spleen (in the upper left abdomen).

A blood sample will be taken to test for mono. The first blood test might be negative, but a complete blood count can show that a mono infection appears to be developing. Your provider may ask you to return in a few days for another blood test. If you have mono, this second test will nearly always be positive.

How is it treated?

There is no specific drug treatment for mono. Because it is a viral illness, antibiotics are not helpful.

The most important thing you can do is to get plenty of rest. Take acetaminophen for the fever and sore throat.

If your symptoms seem to be worsening rather than gradually improving after 1 to 2 weeks, tell your health care provider. You could develop strep throat or a sinus infection. An uncommon complication of mono is an abscess (pocket of infection) on the tonsil. These three infections do need to be treated with antibiotics.

Sometimes the mono infection causes the tonsils to become so big that they nearly block the throat. Steroids (Prednisone) may be prescribed to try to decrease the size of the tonsils.

The virus may inflame your liver, so it is important not to drink alcohol when you have mono. Alcohol could further injure your liver.

An enlarged spleen could rupture if it were hit or strained. A rupture of the spleen causes severe bleeding and is a medical emergency. For this reason, you should avoid heavy lifting and any kind of jarring activity or contact sport. Your activities will need to be restricted until your spleen returns to a normal size. Otherwise, you will gradually be able to return to school, work, and sports.

How long will the effects last?

Your symptoms may get worse for 2 or 3 weeks after they first appear. Usually the fever, sore throat, and extreme fatigue last about 1 to 2 weeks. It can take several weeks, and in some cases several months, for the body's immune system to overcome the virus. You may continue to be infectious for many months after you recover from the infection.

The Epstein-Barr virus stays in the body even after you recover. You could have mono again, but this does not usually happen.

What can be done to help prevent infectious mononucleosis?

The best way to prevent others around you from getting mono is for them to avoid contact with your saliva. They can do this, for example, by avoiding kissing you and by not sharing food or eating and drinking containers and utensils until it has been several days since you had a fever.