usually is caused by the Epstein-Barr virus (EBV). When someone gets mono, the
stays in the body for the rest of that person's life. It can even reappear
in the person's saliva (spit) from time to time. But the person probably won't get
mono symptoms (like being tired all the time, a sore throat, fever, and loss of appetite)
If you have mono symptoms — even if you've had it before — see your doctor. Other
illnesses such as strep
throat and the flu may
cause similar symptoms. Your doctor can make an accurate diagnosis.