Infectious mononucleosis is caused by the Epstein-Barr virus (EBV). Most people are exposed to this very common virus as children or teenagers, and not everyone who is exposed or infected develops symptoms. In fact, most adults have had mono in the past whether they knew it or not.
You can get mononucleosis through direct contact with saliva (spit) from someone infected with EBV, such as by kissing, sharing a straw, a toothbrush, or an eating utensil. Because so many people get the virus without having symptoms, it is often impossible to tell when someone may be passing the virus to others.
Symptoms usually begin to appear 4 to 7 weeks after infection with the virus. Signs that you may have mono include:
People who have mono may have different combinations of these symptoms (or no symptoms at all). Because the symptoms of mono are so general and can be signs of other illnesses, it's possible to mistake mononucleosis for the flu, strep throat, or other infections (although some people may have mono and strep throat at the same time).
A simple finger prick test can sometimes pick up mono in the doctor’s office. But even if you do have mono, the test many not be able to tell this during the first 2 weeks of symptoms. More sophisticated blood tests drawn at the laboratory may aid in diagnosis and allows us to follow the stages of recovery from the illness.
When you start to feel better, take it slowly. Although you can return to school or work once your fever disappears, you may still feel tired. Your body will tell you when it's time to rest — listen to it. By taking good care of yourself and resting as much as you need to, you will soon be back to normal, usually within a few weeks. Try building back slowly, starting with one “outing” per day (whether a trip to the pharmacy or going to just 1-2 classes at school). Increase the length of your “outings” gradually; rushing into full activities will often cause setbacks.
All sports should be avoided until the patient is fully recovered (typically 4 weeks after onset of symptoms) and the doctor has given permission to resume activity. An enlarged spleen can rupture, causing internal bleeding and abdominal pain and requiring emergency surgery.
Contact your doctor immediately if you have yellow eyes or yellow skin (sign of spleen rupture).