Can Older People Get Mono?

I am a 55-year-old woman who was told that I have mono. My blood test came back positive for mono. Everything I read says only younger people get this. My joints hurt so badly.

Although I have written many postings on infectious mononucleosis (mono) and the virus that causes it, the Epstein-Barr virus (EBV), I continue to get so many questions similar to that from you today that I thought it would be helpful to revisit this issue.

EBV is a member of the herpes family of viruses, and like all the members of that group, once a person has been infected by the virus, it remains alive in their body for the rest of their lifetime. Herpes I and II, which cause regular herpes, and varicella-zoster virus which causes chickenpox and herpes zoster are other viruses in this same family.

EBV lives in certain blood cells, called B cells, and also in cells in the mouth and throat. Everyone who has been infected by the virus, and that includes 90 percent of the adult population of the U. S., sheds the virus in their saliva occasionally. It is estimated that from 15 to 25 percent of the population is shedding the virus at any point in time. That’s a lot of people. This virus is only spread through contact with saliva and is therefore popularly known as the kissing disease. Many young people ask me when they can resume kissing their boyfriend or girlfriend after they have had mono. Since in most cases they probably got the infection from kissing their boyfriend or girlfriend, I usually say they can start again as soon as they feel well enough. EBV is not spread by cough droplets, or by touching objects handled by someone with mono.

About 50 percent of people catch mono before the age of 10, presumably by being kissed by their parents or others, who of course are spreading the virus 15 to 25 percent of the time. Most children who catch it do not become sick, or have only mild cold symptoms. Therefore, it is desirable I believe, to catch mono as a child, and I do not encourage parents to try to isolate their child with mono from other children.

Of the 50 percent of people who get through childhood without catching EBV, about 12 percent catch it during each year of adolescence or young adulthood. In this age group it is much more likely that the person will become sick with what we call mono, with sore throat, large lymph nodes, and fever. The fever can persist for several weeks, and fatigue or malaise occasionally persists for several months. That’s why it’s best to catch it when you are young. Virtually no one dies of mono, although many adolescents and adults can be very sick with it.

Since 90 percent of people have caught the EBV virus by the time they are 30, it is unlikely, though not impossible, that you would have caught it at age 55. However, if you did, I would expect you to be having sore throat and fever, neither of which you mention. The one symptom that you do mention — joint pains — is not considered to be one of the symptoms of mono.

So why do you have a blood test that shows mono, when it is unlikely that you have the disease? There are quite a few blood tests done to identify the EBV, and several of them, specifically the tests called VCA-IGM and EBNA, remain positive for a person’s lifetime once they have had it. So being positive on one of those tests simply means that you had the disease sometime in the past, probably during your childhood. Many doctors do not have the interpretation of all these antibody tests at their fingertips and, indeed, every time I write about EBV, I have to look them up again myself; so your doctor may have seen the positive antibody test and simply said “Aha, there’s the answer.”

A test called heterophil antibody is sometimes done which does indicate that a person has acute mono, or is having one of the rare relapses of the disease. If you had a positive heterophil antibody test, I couldn’t argue with the diagnosis of mono, but frankly, I suspect that you had one of the other antibody tests which indicate disease in the past.

When these antibody tests first came out in the early 80s, people with Chronic Fatigue and Immune Dysfunction Syndrome (CFIDS, also referred to as chronic fatigue syndrome or CFS) were tested, and most were found to be positive. This lead to the now discredited belief that EBV causes CFIDS. Since we now realize that about 90 percent of all people — both with and without CFIDS — have antibodies to EBV, it is no longer thought that this virus causes the disease.

I suspect that you have some other condition that is causing your severe joint pains. If they don’t get better soon, you should ask your doctor for a referral to a rheumatologist for a more complete diagnosis.

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