Mononucleosis and Sports

What is mononucleosis?

Infectious mononucleosis (IM or "mono") is a common illness among athletes and young adults. The most common age group to get mono is between 15 to 24 years of age. About 2% of college students get infected each year. Many people were exposed to mono at an early age without getting sick and have developed protective antibodies.

How does it occur?

Mononucleosis is caused by the Epstein Barr virus. The time period between getting exposed to the virus and getting sick is about 4 to 6 weeks. Mono is spread by saliva or respiratory secretions. The source of contact is rarely known. Although it has been called the "kissing disease" neither boyfriends/girlfriends nor roommates are commonly the source of infection. A person with mono is usually contagious for the first few weeks of their illness.

What are the symptoms?

When you first get mono you may have symptoms such as headache, fatigue, and loss of appetite. These symptoms usually last 3 to 5 days. After that most people have fever, sore throat, swollen glands (lymph nodes) in their neck and more fatigue. Your tonsils can get enlarged and sometimes covered with pus. It may be very hard for you to drink or eat. You may also have an enlarged spleen (in the upper left abdomen). Your liver may also be inflamed and your eyes may turn slightly yellow.

How is it diagnosed?

Your provider will ask you about your symptoms and examine you. Your provider may order a blood test called a "monospot". This mono test may not be accurate until you have been sick for 5 to 7 days. Some people who have mono never have a positive "monospot" test. A more specific test called an "Epstein Barr antibody test" may be ordered. You may also have a throat swab to check for strep throat, since some of the symptoms are similar.

How is it treated?

A mild case of mono may recover within a few weeks; some cases of mono take 6 weeks or more to recover.

There is no specific drug treatment for mono. Because it is a viral illness, antibiotics are not helpful. Take acetaminophen or ibuprofen for fever and sore throat. It is very important that you drink lots of fluids to avoid becoming dehydrated, and get plenty of rest. Do not drink alcohol when you have mono because alcohol could further hurt your liver. If your tonsils become extremely enlarged your provider may give you a steroid, such as prednisone, to help shrink them. So people who are dehydrated may need to be put in the hospital for intravenous (IV) fluids.

You could develop strep throat or a sinus infection. These infections need to be treated with antibiotics. Some antibiotics can cause a rash if prescribed when you have mono (such as amoxicillin and ampicillin). This does not mean that you are allergic to those antibiotics.

When can I return to my sport or activity?

The biggest worry with mono is the enlargement of your spleen. An enlarged spleen can become fragile and could rupture. If your spleen is enlarged from the mono, it could rupture if it is hit or strained. A rupture of the spleen causes severe bleeding and can be life-threatening. The spleen is most vulnerable during the first 3 weeks that you are sick. During that time you really should just rest. Most people get out of shape after mono and take a while to get their fitness level back. When you first start exercising again you will need to start slowly and gradually increase the amount of exercise as your fitness improves. For example, brisk walking or easy bicycling on a stationary bike. Your provider will re-examine you and tell you when it is safe to return to sports. In particular your provider will check to see if your spleen has returned to normal size. If you are playing a contact sport you may be out for 3 to 6 weeks while your spleen is recovering. Your provider may order a test called an ultrasound or a CT scan to check the size of your spleen. However, spleen sizes are different in different people and no test is perfect in determining if a spleen size has become normal.