Mononucleosis and Epstein-Barr: Are they related?

Yes. The Epstein-Barr virus can cause infectious mononucleosis.

A member of the herpes virus family, Epstein-Barr virus (EBV) is one of the most common human viruses. Most people have been exposed to EBV by age 35 and develop antibodies to it.

In children, EBV typically causes no signs or symptoms. When EBV occurs during adolescence or young adulthood, however, it can cause infectious mononucleosis, also called mono. Signs and symptoms of mononucleosis include fever, sore throat and swollen lymph nodes.

It was once thought that EBV may cause chronic fatigue syndrome, which is similar to chronic mononucleosis. But doctors no longer believe this is true.