• fever
• sore throat
• enlargement of lymph nodes (usually in the neck, armpit, and throat)
• sore muscles
• enlarged spleen (the organ - located under the ribcage on the left side - that functions as a blood filter and antibody producer) 

Loss of appetite and generalized weakness also may be present, especially in adolescents. Nausea, hepatitis, jaundice, severe headache, stiffness, chest pain, and difficulty breathing can occur in some cases. A pink rash can occur all over the body in children who have been treated with ampicillin or amoxicillin.

Younger children may have few or none of these symptoms; instead they may have nonspecific symptoms like fever, slight malaise, and loss of appetite. Adolescents are more likely to exhibit the classic symptoms described above. Some may experience extreme fatigue, staying in bed for more than a week because they feel too weak even to walk around the house.

Infectious mononucleosis is generally a self-limiting disease, which means it goes away on its own in most cases. Occasionally mono can cause complications (which are decribed below).

Description:
Mononucleosis is an illness caused by the Epstein-Barr virus (EBV), a member of the herpesvirus family. Similar symptoms and illness are sometimes caused by cytomegalovirus, which is also a member of this family of viruses.

EBV is transmitted through the saliva. Young children can be infected from the saliva of playmates or family members. Adolescents with the virus can spread EBV through kissing (hence its once popular name, "the kissing disease"). Epidemic outbreaks in hospitals and workplaces have occurred.

Most people who have infectious mononucleosis recover completely with no problem, but sometimes complications from EBV infection can occur.  These can include blood disorders leading to lowered numbers of red and white blood cells because of decreased production of these cells by the bone marrow, or destruction of red blood cells (hemolytic anemia).

Bell's palsy, a usually temporary condition where there is inflammation of one of the facial nerves resulting in weakened or paralyzed facial muscles on one side of the face, can also result from EBV infection.

Other rare complications of EBV infection include rupture of the spleen, inflammation of the heart muscle (myocarditis), involvement of the central nervous system (aseptic meningitis and encephalitis), and a nervous system disorder known as Guillain-Barré syndrome that can paralyze muscles. 

Epstein-Barr virus is usually diagnosed with blood tests. Heterophile antibody levels (antibodies react to infectious organisms in the blood and create immunity) indicate a current infection with EBV. Antibody levels (called "titers") against the EBV virus reveal if there is a current or prior infection from the virus. 

Blood tests usually shows an increase in the overall number of white blood cells. Blood can also be examined under a microscope to determine whether there is an increased number of white blood cells called lympocytes. These white blood cells help fight viral infections, and an increased number of "atypical" lymphocytes usually indicates current infection with mononucleosis.

Studies show that most people have been infected with EBV at some point in their lives, and most have few or no symptoms of viral infection.

Prevention:
There is no vaccine for EBV, but prior infection with the virus usually provides long-lasting immunity. Avoiding contact with the saliva or respiratory secretions of people known to have EBV is advisable.

Incubation:
The incubation period is 10 to 60 days; 7 to 14 days is common for children and adolescents.

Duration:
Mono is a self-limiting disease; symptoms usually go away on their own within 2 to 4 weeks. The fever and sore throat usually subside after 2 weeks, but the enlarged lymph nodes and spleen can persist for a few more weeks. In some children, especially teens, fatigue and weakness may last for weeks, and occasionally months.

Contagiousness:
EBV is contagious - it is transmitted through the saliva of an infected person by coughing, sneezing, and kissing. Susceptible people should avoid contact with those known to have active mononucleosis; the virus can continue to be excreted in saliva and repsiratory secretions for months. In general, strict isolation procedures or special precautions are not needed. People with recent EBV infection should not donate blood.

Professional Treatment:
If there is enlargement of the tonsils or lymph nodes in the neck and throat that interferes with breathing, steroids may occasionally be prescribed to alleviate the situation.

Because mono is caused by a virus, antibiotics such as penicillin won't help unless the child has a secondary infection like strep bacteria.

Home Treatment:
The best treatment for infectious mono is plenty of rest, especially earlier in the course of the illness when symptoms are the worst. Acetaminophen (such as Tylenol) or ibuprofen (such as Motrin) can help to relieve the fever and aching muscles. Never give aspirin to a child who has a viral illness because the use of aspirin in such cases has been associated with the development of Reye syndrome, which can lead to liver failure and death.

After recovery, adolescents frequently are advised not to play sports for at least 1 month. Children with enlarged spleens should avoid contact sports (even wrestling with friends or siblings at home). Sometimes fatigue from mono may persist for a few months, and in this case, any kind of vigorous activity or exercise should be avoided. Any child with an enlarged spleen from infectious mono should be examined by the child's doctor for medical approval before returning to contact sports.

When to Call Your Child's Doctor:
As discussed, EBV infection may affect a wide range of organ systems, and occasional complications can occur. If your child has symptoms of infectious mononucleosis, call your child's doctor so your child can be evaluated. 

It's important to remember that any child with an enlarged spleen should not engage in vigorous activities or play contact sports. Sudden sharp pains in the left upper abdomen in the context of an infection may indicate that the spleen has become involved - if this occurs, call your child's doctor immediately.

Reviewed by: Joel Klein, MD, and Kim Rutherford, MD
Date reviewed: October 2001