Blood DiseasesHuman InterestInfectious Diseases


I thought for sure I wrote a blog about “MONO” a few years ago, but if I did, I can’t find it! What  made me think of “mono” right now? Well, my 13 year old granddaughter, CLAIRE, was just diagnosed with it! For a couple of weeks she had complained of fatigue, a sore throat, tender places in her neck, and had a low-grade fever. My daughter took her to the immediate care clinic where she was examined and tested positive for “mono.” Thus, I thought a refresher on it was a good idea.

During my years in practice, I saw “mono” all the time. Also called Epstein-Barr Virus (EBV) syndrome, Infectious Mononucleosis, is very common among adolescents, teens, and young adults, and at times, can become a serious illness. Of course, any illness can be serious, but “mono” can become severe enough to cause hepatitis, severe enlargement, and even rupture, of the spleen, and chronic EBV syndrome lasting for many years. 

The Epstein-Barr virus (EBV), a member of the herpesvirus family, is the cause of “mono.” It thrives in a human host usually residing in bodily fluids. Saliva is one of EBV’s favorite homes so it naturally follows that “mono” is transmitted to unsuspecting victims via kissing or sharing drinking cups or glasses. It is also much less commonly transmitted via the blood and semen, in a blood transfusion or from sexual contact. Once the virus finds a willing host, it may remain in the saliva for three months.

After exposure to EBV, “mono” symptoms may not appear for 4-6 weeks. Thus, it is sometimes difficult to trace the original source of one’s infection. “Mono” can remain contagious for up to 18 months. When symptoms develop they may begin slowly, or the patient may get sick right away. Fatigue, achiness, sore throat, and tender, swollen lymph nodes are early symptoms. Low grade fever and a measles-like rash can occur, too. This is more commonly a disease of teens and young adults so the physician needs to think “mono” when a young person presents with these symptoms. 

On physical examination the throat is inflamed, at times very severely, and enlarged tender lymph nodes are found in the neck, armpits, and groin. The largest lymph node in the body, the spleen, may be enlarged and tender, too. However, of the dozens of patients I saw with “mono,” I didn’t see many enlarged spleens. I did see, though, some of the very worst sore throats and the largest, most tender, lymph nodes I have ever seen. 

After examination, the next diagnostic step is to get a laboratory test for “mono” and a CBC, a complete blood count. In “mono,” the white blood cell (WBC) count can be high, low, or normal, and to diagnose “mono,” one expects to see a higher than normal number of lymphocytes (a type of WBC) plus immature, atypical lymphocytes. These findings point toward the illness being “mono.” 

Next, more specific confirmatory blood tests are done. The quickest is the MonoSpot test. It detects EBV antibodies, but has a high rate of false positive and false negative results. I relied on this test most of the time. If the CBC had atypical lymphocytes, and if the patient’s history and physical exam findings were consistent with “mono,” the diagnosis was fairly certain. 

Purists, however, aren’t convinced of “mono” unless they do direct measurement of the levels of antibodies produced by the EBV. There is a panel of blood tests called Epstein-Barr Viral Titers, which could tell the doctor where in the course of the illness the patient stood. I only ordered EBV titers if I was unsure of the diagnosis, or if I was suspecting chronic fatigue syndrome. 

The treatment of mono is non-specific meaning we treat the patient’s symptoms. Rest, fluids, OTC meds for pain or fever, gargling, symptom-directed treatments, and time are the mainstays. For patients with tender, swollen nodes and severe sore throats, I often prescribed prednisone or a Medrol dose pack. These corticosteroids helped reduce inflammation and shrink enlarged lymph nodes as well as stimulating appetite and improving energy. The course of the clinical illness was shortened by adding steroids, and the patient generally felt better. Antibiotics have no role in the treatment of “mono” and are contra-indicated.

The duration of illness in “mono” is variable so it is very difficult to decide when the patient is “well.” I used the CBC to help me decide. During convalescence, I had the patient get a CBC every week. I watched the number of atypical lymphocytes, and once there were none and once the lymphocyte count was back to normal, and if the patient’s symptoms were better, I felt confident the illness was over. Symptomatically they were better, but they were still contagious; they still needed to carefully avoid transmission to others, even though they were well. 

Most cases of “mono” resolve, but a small percentage of cases do not. Those patients who don’t improve develop chronic Epstein-Barr virus syndrome, which fortunately is rare. It is similar to chronic fatigue syndrome, a vague, poorly understood illness. Any way, “mono” is very common, and is almost a rite of passage for teens and young adults. I saw cases of “mono” every month, and some kids were really sick. Corticosteroids were always effective for turning a very sick person into one who was well in just a matter of days. I’m thankful for that. 

Dr. G’s Opinion: Infectious mononucleosis is a contagious disease common among teens and young adults.  It is treatable and usually has no chronic long-term effects. Most patients who have “mono” certainly remember it. Some of the worst sore throats I saw were in “mono” patients. But they get better. The virus will always be with us because it hides in the saliva of well, unsuspecting people, and if the doctor doesn’t think about it, he/she won’t test for it. “Mono” must be in the back of every physician’s mind and treatment should be started early. 


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  1. I remember having mono in the 3rd grade. I was home for a half semester and I had to repeat that time. I was home sick with 2 of my brothers. The board of health was going to put a quarantine sign on the house. The neighbors complained that we were the carriers. I think that my mother must of gone crazy during that period. I think shortly after that recovery my brothers caught the mumps. It was in the days when the doctor made house calls. We were not allowed out of the house. He would not want us in the office anyway.
    Poor mom !

    1. Wow! You had a bad case! A lot more is known about mono now such as prednisone shortens the course of the illness. Your neighbors were not at risk of getting it because they would have had to kiss you or drink after you to get it. A quarantine was unnecessary, too. Maybe the mumps had something to do with the quarantine. Your poor mom, is right!

      1. Shortly after that we had the measles. Poor mom is right. Thats why i dont know when to tell people i graduated high school. I dont think that Bob ever got Andy of these diseases. Just my other 2 brothers and myself.

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