Recurrent or chronic mononucleosis: Is there such a thing?

Rarely, mononucleosis, or "mono," can recur or become chronic.

Most cases of infectious mononucleosis are caused by infection with the Epstein-Barr virus (EBV). EBV is a member of the herpesvirus family. Like other herpesviruses, once you are infected with EBV, you carry the virus, usually in a latent, or dormant, state for the rest of your life.

In the United States, up to 95 percent of adults have been exposed to EBV, according to the Centers for Disease Control and Prevention. However, most never develop symptoms of illness and simply carry the latent virus in their bodies.

Periodically, EBV may reactivate and be detectable in the saliva of infected individuals. Reactivation of EBV — unlike other herpesviruses — usually occurs with no symptoms. However, there are exceptions. Reactivated EBV in people with impaired immune systems, such as those with AIDS, may cause illness.

Also, it was once thought that reactivated EBV infection might cause chronic fatigue syndrome. But doctors no longer believe this is true.

Rarely, mononucleosis can result in a serious condition called chronic active EBV infection. This is characterized by persistent illness more than six months after initial diagnosis of infectious mononucleosis. A diagnosis of chronic active EBV infection can be made by blood tests and tissue biopsies that show elevated levels of the virus.

Your daughter should be evaluated by a doctor to determine the cause of her current symptoms. Other conditions can mimic the symptoms of mononucleosis.