How long can mono stay in body?

Forever: The virus may stay in the body forever as do some other viruses like the chickenpox virus. Most of those infected with the virus will actively shed the germ in saliva for 3-4 weeks while a few do for 3 months. Some will occasionally transiently shed the virus in saliva on and off for many years.Symptoms rarely remain after the first 3 wk-3m period.Chronic fatigue is not caused by mono. (cdc).