Mononucleosis and Epstein-Barr: What's the connection?

Epstein-Barr virus (EBV), a widespread human herpes virus, can cause infectious mononucleosis — but usually, it doesn't. In fact, most EBV infections aren't noticeable, even when they're most active in your body. By age 35, almost everyone has antibodies to EBV, indicating past infection.

It takes more than an uncovered cough or sneeze to transmit EBV. During primary infection, people shed the virus in saliva. You need close contact, such as kissing or sharing a cup with an infected person, to catch EBV.

The infection generally stays under the radar in children, but teenagers and young adults aren't as lucky. In that age group, up to half of EBV infections cause mononucleosis.

Mononucleosis signs and symptoms, which include fever, sore throat and extreme fatigue, can make you too sick to do much for weeks, but you will get better. Contrary to what you may have heard, there's no support for the theory that EBV causes chronic fatigue syndrome.