Should i go to work if i have mono? how contagious is it?

Mononucleosis: Mononucleosis is a viral infection (EBV) that can cause extreme fatigue, sore throat, cough, abdominal pains, headaches, swollen lymph nodes and other symptoms. Spleen enlargement is an uncommon but serious possibility. EBV is a lifelong infection, but usually remains silent. Viral shedding is at it's peak just before symptoms start and until fever resolves and you are not feeling as ill.