Methodist Hospital - Visiting Nurse Assn. When children are infected with the virus, they usually do not experience any noticeable symptoms. However, uninfected adolescents and young adults who come in contact with the virus may develop infectious mononucleosis in nearly 50 percent of exposures. The cytomegalovirus is actually a group of viruses in the herpes simplex virus family that often cause cells to enlarge. About 80 percent of adults who are infected with the cytomegalovirus usually do not develop symptoms.
Mononucleosis usually lasts for one to two months.
The following are the most common symptoms of mononucleosis. However, each individual may experience symptoms differently. Once a person has had mononucleosis, the virus remains dormant in the throat and blood cells for the rest of that person's life. Once a person has been exposed to the Epstein-Barr virus, a person is usually not at risk for developing mononucleosis again. The symptoms of the mononucleosis may resemble other medical conditions.