Infectious Mononucleosis -

Infectious Mononucleosis - Mono: Overview

Mononucleosis, often called "Mono", is a usually mild self-limiting acute viral infection and, in most cases, does not deserve its bad reputation.  While mono is not usually considered a serious illness, it may have serious complications.  Usually (85% of the time) caused by the Epstein-Barr virus (EBV), it usually runs its course quickly and rarely produces any serious complications.  There are, however, other viruses that may produce a mono-like illness.  A less common form of mononucleosis is caused by cytomegalovirus (CMV).

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Mononucleosis is an illness that affects teenagers and young adults, mainly ages 14 to 30, but can occur in children and older adults.  It has been estimated that approximately 50% of students have had mono by the time they enroll in college.

Signs and Symptoms

Many times the symptoms are so mild that it is not recognized for what it is: The symptoms of mononucleosis may be the same as many other illnesses, such as "colds" or strep throat.  For this reason, it is particularly difficult to diagnose in the early stages of the illness, although the diagnosis is usually based on symptoms and a physical exam.  Symptoms usually disappear within 2-4 weeks, with fatigue sometimes lingering longer.

Diagnosis and Tests

Confirmation, if necessary, can be accomplished by either of two blood tests:

  1. EBV causes an increase in a specific type of white blood cell, the atypical lymphocyte.  A white blood cell count, WBC, will reflect this change commonly seen in people who have mononucleosis.  Diagnostic problems can result because enlarged lymphocytes are common with mono, but can also be a symptom of leukemia.  Blood tests can distinguish between the type of white cell seen in leukemia and that with mono.
  2. The mono spot test identifies an antibody which is present in mononucleosis and is the test most commonly used to tell whether someone has mono or some other ailment.  This test may not become positive until one has had symptoms for 5-14 days and may remain positive for months to years.  It is important to remember the mono test merely helps to make the diagnosis; it does not indicate the severity of the disease and does not predict how long symptoms will last.  This blood test detects the antibodies (proteins) that the body makes to fight EBV or CMV.  Because it takes a while for antibodies to develop after infection, your doctor may need to order or repeat the test one to two weeks after you develop symptoms.  At that time the test is about 85% accurate.

Other tests your doctor might order include a complete blood count (CBC) to see if your blood platelet count is lower than normal and if lymphocytes are abnormal, and a chemistry panel to see if liver enzymes are abnormal.

Treatment and Prevention

There are no conventional medical treatments to cure mononucleosis, only those that help manage the symptoms.  In approximately 20-30% of people with mononucleosis there is a concurrent bacterial throat infection.  Any antibiotics prescribed may help with the sore throat, but not the EBV infection.

Relieve pain and fever with analgesics.  Contact sports should be avoided while the spleen is enlarged.  Cold drinks and frozen desserts are both ways to relieve sore throat symptoms.  Doctors also recommend gargling with saltwater (about half a teaspoon salt to 8 ounces of warm water) and sucking on throat lozenges available over-the-counter in pharmacies and other stores.  If throat or tonsils are infected, a throat culture should be taken so the doctor can prescribe an appropriate antibiotic.  Ampicillin is usually not recommended because it sometimes causes a rash that can be confused with the pink, measles-like rash that 1 out of 5 mono patients develops.

Acetaminophen is preferable to aspirin for pain and fever relief because of the association of the EBV and Reye's syndrome in children.  In most cases of mononucleosis, hospitalization is not indicated.  It has been shown that those who remain active to the limit of personal comfort get well more rapidly than those who remain in bed.

EBV is found in moist, exhaled air, and in nose or mouth secretions.  It is not as contagious as many other viruses but may be transmitted through direct contact.  This explains its nickname of the "kissing disease".  There is a long incubation period of 30 to 50 days from the time one is exposed to the virus to the time one gets sick.  In addition, the virus can be transmitted in other ways, such as sipping from the same straw or glass as an infected person – or even being close when the person coughs or sneezes.

Isolation of the patient is not indicated; one can not catch mononucleosis by sitting in the same room with someone who has it, although persons who have had mononucleosis can shed the virus periodically in their saliva for the rest of their lives.  Some people can have the virus in their systems without ever having symptoms, and still be infectious.

Prognosis; Complications

Fever usually abates in about 10 days, and swollen lymph glands and spleen heal in 4 weeks.  Fatigue usually resolves within a few weeks, but may linger for 2 to 3 months.

Possible complications include:

Signs, symptoms & indicators of Infectious Mononucleosis - Mono:

Lab Values - Cells

Symptoms - Food - General

Symptoms - General

Recent onset fatigue

Intermittent and moderate fatigue is one of the early and main symptoms of mononucleosis.  It almost always disappears within 2-4 weeks and lasts for months in only 1-2% of cases.  Prospective studies among University populations have established that 20% of patients returned to work or school within 1 week and 50% within 2 weeks.

Symptoms - Glandular


Symptoms - Head - Eyes/Ocular

Symptoms - Liver / Gall Bladder

(Possible) enlarged liver

Mild enlargement of the liver may occur.

Symptoms - Metabolic

Having a high/having a moderate/having a slight fever

A low grade fever occurs at first, and then rises to above 100°F after the third or fourth day.

Symptoms - Respiratory

Current/current very sore throat

The sore throat usually seen in mononucleosis typically clears in 7-19 days, possibly fewer.

Symptoms - Skin - Conditions

Conditions that suggest Infectious Mononucleosis - Mono:

Lab Values

Infectious Mononucleosis - Mono suggests the following may be present:


Epstein-Barr Virus (EBV)

When infection with EBV occurs during adolescence or young adulthood, it causes infectious mononucleosis 35% to 50% of the time.  85% of infectious mononucleosis cases are caused by EBV.

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Infectious Mononucleosis - Mono can lead to:


Organ Health

Enlarged Spleen

About 50-75% of people with mononucleosis have some spleen enlargement, usually seen two to three weeks after they first become sick.  Whether or not the spleen is enlarged, people who have mono should not lift heavy objects or exercise vigorously – especially participating in contact sports – for two months after they get sick, because these activities increase the risk of rupturing the spleen, which can be life-threatening.  If you have mono and get a severe sharp, sudden pain on the left side of your upper abdomen, go to an emergency room immediately.

Infectious Mononucleosis - Mono could instead be:


Cytomegalovirus (CMV) Infection

Mononucleosis-like disease may be caused by the cytomegalovirus (CMV) as well as the classic mononucleosis of the Epstein-Barr virus (EBV).  Both viruses are members of the herpes virus family.  Mononucleosis caused by EBV is the most frequently encountered type and is responsible for approximately 85% of infectious mononucleosis cases.  Sore throat is less common in people who have CMV mono than in those infected with EBV.

Pharyngitis ("Strep Throat")

If your throat is sore, having a throat culture is usually a good idea for several reasons.  First, the symptoms of mono and strep infection (including that caused by Strep-A, a particularly serious form of strep) are very similar.  Second, strep throat or other throat infections can develop at any time during or shortly after infectious mononucleosis infection.  In any case, it is important that throat infections be diagnosed as soon as possible and treated with antibiotics that can kill the organism responsible for the infection.

Recommendations for Infectious Mononucleosis - Mono:


High/Increased Protein Diet

A high protein, decreased fat diet and vitamin supplements may be recommended.


Not recommended

Those under 20 should not take aspirin unless a doctor approves it.  In children and teens, aspirin taken for viral illnesses has been associated with the potentially fatal disease Reye syndrome.

Oxygen/Oxidative Therapies

Ozone / Oxidative Therapy

According to doctors who have used ozone in mononucleosis, resolution of symptoms is accomplished more quickly.


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Weak or unproven link: may be a sign or symptom of; may suggest
Weak or unproven link:
may be a sign or symptom of; may suggest
Strong or generally accepted link: is often a sign or symptom of; often leads to; is sometimes misdiagnosed as
Strong or generally accepted link:
is often a sign or symptom of; often leads to; is sometimes misdiagnosed as
Definite or direct link: suggests; usually leads to; is often misdiagnosed as
Definite or direct link:
suggests; usually leads to; is often misdiagnosed as
Strong counter-indication: often contraindicates
Strong counter-indication:
often contraindicates
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May be useful:
may help with
Caution: is sometimes not recommended for
is sometimes not recommended for
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