Other abnormalities may occur in infectious mononucleosis, but these are very rare. This disease may be contracted by kissing a person who carries the virus in the saliva. Other means of transmission have not been proven. The illness is unpredictable. Many people never have to be bedridden because their illness is so mild.
Some people apparently have mono and recover without knowing they ever had it.
Loss of energy Fatigue may be a factor in the recovery period. How long you remain tired from this illness varies considerably. Many people have little or no fatigue at any time. A few people will be tired for many months. Some will be somewhat tired for one to four weeks following a few days of fever at the beginning of their illness, gradually recovering their full strength and energy.