Infectious mononucleosis is an illness caused by the Epstein-Barr
virus (EBV), a member of the herpes family of viruses. Mononucleosis
takes its name from the blood's mononuclear cells, white blood cells
whose numbers increase in the bloodstream when a person has a
mononucleosis infection. Although other viral infections, especially
those caused by cytomegalovirus, can cause mononucleosis-like
symptoms, classic mononucleosis is caused by EBV.
Mononucleosis can be passed from person to person in saliva, in
coughs and sneezes, and through close (mouth-to-mouth) contact of
mucous membranes during kissing. This is why mononucleosis has been
nicknamed "the kissing disease." Young children usually
become infected through contact with the saliva of sick playmates or
family members. Although epidemics of mononucleosis sometimes
happen, they usually affect persons living within the same home or
institution, rather than larger communities of persons living in
Some studies suggest that most people are infected with EBV at
some point in their lives, although the majority have few or no
symptoms. Once this infection happens, the virus lingers in an
inactive form within the body's white blood cells. Although EBV
probably stays there for the rest of a person's life, it doesn't
produce an active infection with symptoms.
What are the symptoms?
Most people usually think of fatigue as the main symptom of
mononucleosis, and it's true that this can be a major complaint.
Other classic symptoms of mononucleosis are fever, sore throat, and
swollen glands (enlarged lymph nodes) in the neck, armpit, and
throat. The spleen, an important abdominal organ that filters blood
and produces antibodies, may become enlarged as well.
Loss of appetite, weakness, and sore muscles are other common
symptoms, especially in adolescents. Nausea, hepatitis, jaundice,
headache, stiffness, chest pain, and difficulty breathing have also
been reported. Sometimes a widespread pink rash appears, especially
in those who have been treated with ampicillin.
Younger children with mononucleosis may have no symptoms of
infection, or they may have only vague complaints like malaise (a
nonspecific "sick" feeling), loss of appetite, or fever.
Of all age groups, adolescents are most likely to have the classic
symptoms of fatigue, fever, sore throat, and swollen glands. Some of
these young people suffer from such extreme fatigue that they stay
in bed for days, and they may even feel too weak to walk around the
A strange "Alice in Wonderland" syndrome also has been
reported by some patients with mononucleosis. Just as Alice did in
her story, these patients see objects around them as being distorted
In general, a susceptible person who has been exposed to someone
with mononucleosis will probably come down with the illness in about
ten days to 60 days.
How is it treated?
Doctors make the diagnosis of mononucleosis by collecting a blood
sample and looking at it under a microscope to check for an abnormal
number of white blood cells. Other types of blood tests may show an
increase in antibody levels against EBV. (Antibodies are defensive
immune proteins produced by the body in response to an infection.)
Right now, there is no antiviral medicine to treat mononucleosis
effectively. Most cases can be cared for at home using
nonprescription medicines, such as acetaminophen, to relieve fever
and pain. Bed rest also helps many children with mononucleosis,
especially if they are suffering from severe fatigue.
In some children with mononucleosis, loss of appetite is one
symptom of a mild liver inflammation. In these cases, some experts
recommend giving the child a diet high in carbohydrates and low in
Since mononucleosis can cause enlargement of the spleen and make
the spleen more susceptible to injury, many adolescents who are
recovering from mononucleosis are advised not to participate in
athletic events for three to four months. All patients with enlarged
spleens should definitely avoid contact sports until the size of the
spleen returns to normal.
Doctors sometimes use steroid medication to treat mononucleosis
if the tonsils or lymph nodes in the throat become so enlarged that
they interfere with breathing. Antibiotics may also be needed to
treat a secondary bacterial throat infection in a person who already
has the viral infection of mononucleosis.
When is it over?
Infectious mononucleosis is usually a self-limited illness, which
means that it just runs its course and then goes away without too
much of a problem. Fever and sore throat usually subside after about
two weeks, but enlarged lymph nodes and spleen can persist for a few
weeks more. In some cases, fatigue and weakness may last for months.
In rare cases, complications do occur. These may include blood
disorders leading to dramatically lowered numbers of platelets (thrombocytopenia),
white blood cells (agranulocytosis), or red blood cells (hemolytic
anemia). Other less common complications include rupture of the
spleen, inflammation of the heart muscle (myocarditis), inflammation
of the brain or its covering membranes (encephalitis or aseptic
meningitis), and a paralyzing disorder known as Guillain-Barré
One attack of infectious mononucleosis is all that most people
will ever have in a lifetime. Once a child has been infected with
the virus, it will stay in his body in a dormant form. The virus is
still present but will probably not actively produce another
infection with symptoms.
How can I keep my kids from getting it?
Since there is no vaccine against EBV, the most parents can do to
prevent mononucleosis is to have their children avoid contact with
the saliva of infected persons. Also, any family member with
mononucleosis should not share drinking glasses or cutlery with
anyone else in the household.
When should I call my doctor?
Check with your doctor whenever your child has a combination of
fever, sore throat, enlarged lymph nodes (swollen glands), and
If your child has been diagnosed with mononucleosis, call your
doctor immediately if he starts to complain of sudden, sharp pains
in the left upper portion of his abdomen, where the spleen is
located. Mononucleosis can affect the spleen and make it prone to