<human>:  When does the Epstein-Barr virus cause mononucleosis?
<bot>: The Epstein-Barr virus is a herpes virus that causes mononucleosis. It is spread through saliva and is most common in adolescents and young adults. It can cause a variety of symptoms, including fever, sore throat, swollen lymph nodes, and fatigue. It usually goes away on its own within a few weeks, but it can last for several months.