What is mononucleosis?
Mononucleosis, also known as "mono," is an infectious disease that is
usually caused by the Epstein-Barr virus (a herpes virus). Other viruses can
also cause mononucleosis. Mononucleosis is not considered a serious illness, but
its symptoms may be severe enough to prevent a person from engaging in normal
activities for several weeks. The classic symptoms of this illness tend to occur
more frequently among teenagers, especially those 15 to 17 years old, and in
adults in their 20s.
What are the symptoms of mononucleosis?
The most common symptoms of mononucleosis are fever, sore throat, and
swollen lymph glands in the neck, under the arms, and in the groin area. Other symptoms include the following:
- muscle aches or weakness
- white patches in the throat
- skin rash
- loss of appetite
In addition to these symptoms, the spleen (an abdominal organ
that stores and filters blood) may become enlarged. About half of those who have
mononucleosis have enlargement of the spleen, usually 2 to 3 weeks after they
The incubation period—the time it takes symptoms to appear after
a person becomes infected with the virus—can be 4 to 6 weeks. Symptoms of
mononucleosis usually last for 1 to 4 weeks, but it might take as long as 2
months before you feel well enough to resume all of your normal activities.
How is mononucleosis spread?
Mononucleosis is usually acquired by contact with the saliva or mucus of a
person who is infected with or is carrying the virus. (Mononucleosis is also known as the
"kissing disease," because it can be acquired through kissing.) Occasionally, it
can be spread by coughing or sneezing, or when an infected person shares food or
tableware with another person.
It is nearly impossible to prevent Epstein-Barr infections, because most healthy people carry the virus and can pass it on to others. After the virus enters the body, the immune system begins to produce antibodies against it. The Epstein-Barr virus remains inactive in the body throughout life, but it may reactivate from time to time. However, reactivation of the virus does not result in clinical symptoms in individuals who have normal immune systems.
How common is mononucleosis?
The Epstein-Barr virus is a very common virus. About 85% to 90% of American
adults have developed antibodies to the Epstein-Barr virus by the time they are
40 years old, which means that they have been infected with the virus at some
point in their lives. Most individuals are infected with this virus early in
life (prior to the adolescent years), and most of these children have no or very
mild symptoms from it. Adolescents, especially teens 15 to 17 years of age, and
young adults who become infected with this virus are most likely to develop the
classic symptoms of mononucleosis.
How is mononucleosis diagnosed?
Mononucleosis is usually diagnosed based on the patient’s symptoms of fever,
sore throat, and swollen lymph glands. The doctor may order blood tests,
particularly the mono spot test. This test detects antibodies to the
Epstein-Barr virus, but sometimes it is inaccurate (yields a false negative)
during the first week of infection. Other blood tests, such as a complete blood
count, might be done to see if the number of lymphocytes is higher than normal,
which may support the diagnosis. Occasionally, titers of antibodies against the
viruses that cause mononucleosis may need to be done to confirm the diagnosis.
How is mononucleosis treated?
There are no medications that can treat mononucleosis, because antibiotics
and antiviral drugs are not effective against the virus. If you are diagnosed
with mononucleosis, here are some suggestions for how to deal with it:
- Get lots of rest, preferably bed rest, especially the first week or two.
- Drink plenty of water and other fluids.
- Take nonprescription pain relievers, such as ibuprofen (or
acetaminophen, if you cannot take ibuprofen) to help relieve the fever and
muscle aches that are common symptoms.
- To help soothe a painful sore throat, use throat lozenges, drink cold
beverages, or eat frozen desserts, such as popsicles.
- Gargle with salt water several times a day if your throat feels sore.
Prepare the salt water solution by dissolving about one-half teaspoon of
salt in 8 ounces of warm water.
- Avoid engaging in any strenuous physical activity, such as exercise,
heavy lifting, or contact sports, for at least 4 to 6 weeks after being
diagnosed with mononucleosis. If your spleen has become enlarged, there is a
small risk that it might rupture from strenuous activity.
Are there any symptoms that require medical attention?
If you have an unusually painful or persistent sore throat or have
difficulty breathing or swallowing because your tonsils are swollen, see a
healthcare professional. Your doctor may perform a throat culture to see if you
have a streptococcus infection (strep throat). Streptococcal infections are
fairly common when you have mononucleosis and can be treated with antibiotics.
If you have mononucleosis and feel a sudden, sharp, severe pain in your left side in the upper abdomen,
go to a hospital or call 9-1-1. The pain may be a sign of a ruptured spleen, which is a very rare complication of mononucleosis.
Symptoms lasting longer than 4-6 weeks are very rarely due to the effects of mononucleosis.
Centers for Disease Control and Prevention. National Center for Infectious Diseases. Epstein-Barr Virus and Infectious Mononucleosis.
www.cdc.gov Accessed 6/16/2011
Merck Manuals Online Medical Library. Infectious Diseases: Herpesviruses: Infectious Mononucleosis
www.merckmanuals.com Accessed 6/16/2011
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