Infectious Mononucleosis

Infectious Mononucleosis

Infectious mononucleosis, "mono", "kissing disease", and glandular fever are all terms popularly used for the very common illness caused by the Epstein-Barr virus (EBV). EBV is a member of the herpesvirus family. The characteristic symptoms of infection with EBV include fever, fatigue, malaise, and sore throat.


The designation "mononucleosis" refers to an increase in one type of white blood cells (lymphocytes) in the bloodstream relative to the other blood components as a result of the EBV infection.


The EBV can infect any person. As previously discussed, the majority of people have become infected with the virus by the time that they reach adulthood, and the majority of these infections produce no symptoms or are not recognized as mono.


Mono is most often diagnosed in adolescents and young adults, with a peak incidence at 15-17 years of age. However, it is also seen in children. Generally, the illness is less severe in young children and may mimic the symptoms of other common childhood illnesses, which may explain why it is less commonly diagnosed or recognized in this younger age group.


The initial symptoms of mono are:


  • a general lack of energy or malaise,
  • fatigue,
  • a loss of appetite,
  • chills.


These initial symptoms can last from one to three days before the more intense symptoms of the illness begin.


The more common intense symptoms include:

  • a severe sore throat,
  • fever,
  • swollen lymph nodes (glands) in the neck area.


It is typically the severe sore throat that prompts people to contact their doctor.


What are the signs of mono?


In addition to a fever from 102 F-104 F, the most common signs of mono are:

  • a very reddened throat and tonsils;
  • swollen lymph glands in the neck.


The tonsils have a whitish coating in at least one-third of the cases. Thespleen (sometimes referred to as the body's biggest lymph node) is anorgan found in the left upper abdomen underneath the rib cage, which becomes enlarged or swollen in about 50% of patients with mono. An enlarged liver and abnormalities in liver function tests (blood tests) may be detected (see Complications, below).


About 5% of patients have a splotchy red rash over the body, which has a similar appearance to the rash ofmeasles. Early in the course of disease (over the first few days of illness), a temporary swelling (edema) of both upper eyelids may appear.


The EBV that causes mono is found throughout the world. By the time most people reach adulthood, an antibody against EBV can be detected in their blood. In the U.S., up to 95% of adults 35-40 years of age have antibodies directed against EBV.


This means that most people, sometime in their lives, have been infected with EBV. The body's immune system produces antibodies to attack and help destroy invading viruses and bacteria. These specific antibodies can be detected in the blood of people who have been infected.


While there are other illnesses falling under the broad classification of mononucleosis that can cause similar symptoms (cytomegalovirus [CMV] is one example) and an increase in blood lymphocytes, the form caused by the EBV is by far the most common.


In most cases of mono, no specific treatment is necessary. The illness is usually self-limited and passes much the way other common viral illnesses resolve. Treatment is directed toward the relief of symptoms.


Available antiviral drugs have no significant effect on the overall outcome of mono and may actually prolong the course of the illness. Occasionally, Strep throat occurs in conjunction with mono and is best treated with penicillin or erythromycin (E-Mycin, Eryc, Ery-Tab, PCE, Pediazole, Ilosone). 


Ampicillin (Omnipen, Polycillin, Principen) and amoxicillin (Amoxil, Dispermox, Trimox) should be avoided if there is a possibility of mono since up to 90% of patients with mono develop a rash when taking these medications.


They may then be inappropriately thought to have an allergy to penicillin. Antiviral medications have not been shown to be of benefit in treating the symptoms of mono.


For the most part, supportive or comfort measures are all that is necessary. Acetaminophen (Tylenol) can be given for fever and any headache or body aches. A sufficient amount of sleep and rest is important. The throat soreness is worst during the first five to seven days of illness and then subsides over the next seven to 10 days. The swollen, tender lymph nodes generally subside by the third week.


A feeling of fatigue or tiredness may persist for months following the acute phase of the illness. It is recommended that patients with mono avoid participation in any contact sports for at least four weeks after the onset of symptoms to prevent trauma to the enlarged spleen.


The enlarged spleen is susceptible to rupture, which can be life threatening. Cortisone medication is occasionally given for the treatment of severely swollen tonsils or throat tissues which threaten to obstruct breathing.


Patients can continue to have virus particles present in their saliva for as long as 18 months after the initial infection. When symptoms persist for more than six months, the condition is frequently called "chronic" EBV infection. However, laboratory tests generally cannot confirm continued active EBV infection in people with "chronic" EBV infection.

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