Mononucleosis: Can it recur?

Two years ago, my daughter was diagnosed with mononucleosis. Now she's having some of the same symptoms again. Can mono recur? I thought that once you got mononucleosis you couldn't get it again.

- Colleen / Illinois

Answer

Most people who have infectious mononucleosis, or mono, only get it once. Rarely, however, mononucleosis may recur months or even years later.

Most cases of mononucleosis are caused by infection with the Epstein-Barr virus (EBV). Once you're infected with EBV, you carry the virus — usually in a dormant state — for the rest of your life. Periodically, however, the virus may reactivate. When this happens, the virus can be detected in your saliva — but you're not likely to become ill. Rarely, reactivated EBV may cause illness in people who have weak immune systems, such as those who have AIDS.

It's important to note that mononucleosis sometimes leads to a serious condition called chronic active EBV infection, which is characterized by persistent illness more than six months after the initial mononucleosis diagnosis.

Consult your daughter's doctor to determine the cause of her current symptoms. Keep in mind that many other conditions, such as hepatitis and toxoplasmosis, can mimic the symptoms of mononucleosis.

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