Can I Get Mononucleosis More Than Once?

Is it possible to get mononucleosis more than once?

With viral infections such as this, the answer is often “no” — having the virus once confers immunity. While that’s true most of the time with infectious mononucleosis, or IM, it’s not always the case. So my answer to your question has to be a qualified “yes.”

About 90 percent of the time, IM is caused by the Epstein-Barr virus, a member of the herpesvirus family. Sometimes other viruses cause it, most commonly another herpesvirus called cytomegalovirus, or CMV. Some experts say CMV causes a different ailment than mononucleosis, but from the patient’s perspective, the experience of the disease is nearly identical.

Mononucleosis is a self-limiting disease — it goes away by itself. But the virus doesn’t leave the body. It remains in a sort of dormant state and rarely reactivates unless something goes seriously wrong with the immune system. So you can get it again in the rare case that the virus reactivates or when it’s caused by a different virus.

A large percentage of children catch IM by the age of 5. Symptoms in young children tend to be so mild that parents may not realize the child is sick. Those who don’t get it in early childhood are likely to come down with the “kissing disease” between the ages of 15 and 30. At this point, it’s somewhat more severe and may cause sore throat, swollen glands, fatigue, fever, headache, loss of appetite and an enlarged spleen. Still, it normally goes away by itself within a matter of weeks.

As you can see by the symptoms, other conditions may resemble IM. People who have had it before may think they’re getting it again, when in reality they have strep throat, tonsillitis, influenza or some other ailment. A doctor can usually pin down a diagnosis of IM from the symptoms, especially if the spleen is enlarged, and with the help of one or more blood tests.