Infectious Mononucleosis

Mononucleosis is an acute infectious disease that causes fever, sore throat, and cervical lymphadenopathy, the hallmarks of the disease. It also causes hepatic dysfunction, increased lymphocytes and monocytes, and development and persistence of heterophil antibodies. The disease primarily affects young adults and children, although in children, it's usually so mild that it's often overlooked.

The prognosis is excellent, and major complications are uncommon.

Causes

Infectious mononucleosis is caused by the Epstein-Barr virus (EBV), a member of the herpes group. Apparently, the reservoir of EBV is limited to humans.

EBV is spread by contact with oral secretions. It's frequently transmitted from adults to infants and among young adults by kissing. It has also been transmitted during bone marrow transplantation and blood transfusion.

Signs and symptoms

Mononucleosis usually lasts for one to two months. The following are the most common symptoms of mononucleosis. However, each individual may experience symptoms differently. Symptoms may include:

• fever
• swollen lymph glands in the neck, armpits, and groin
• constant fatigue
• sore throat due to tonsillitis, which often makes swallowing difficult
• enlarged spleen
• liver involvement, such as mild liver damage that can cause temporary jaundice (a yellow discoloration of the skin and eye whites due to abnormally high levels of bilirubin (bile pigmentation) in the bloodstream

Diagnostic tests 

The following abnormal laboratory test results confirm infectious mononucleosis: 

• An increase in white blood cell (WBC) count of 10,000 to 20,000/mm during the second and third weeks of illness. Lymphocytes and monocytes account for 50% to 70% of the total WBC count; 10% of the lymphocytes are atypical.
• A fourfold increase in heterophil antibodies (agglutinins for sheep red blood cells) in serum drawn during the acute phase and at 3- to 4-week intervals.
 
• Antibodies to EBV and cellular antigens shown on indirect immunofluorescence. Such testing usually is more definitive than heterophil antibodies but may not be necessary because the vast majority of patients are heterophil-positive.
• Abnormal liver function studies.

Treatment

Infectious mononucleosis isn't easily prevented, and it's resistant to standard anti-microbial treatment. Thus, therapy is essentially supportive: relief of symptoms, bed rest during the acute febrile period, and aspirin or another salicylate for headache and sore throat.

If severe throat inflammation causes airway obstruction, steroids can relieve swelling and prevent a tracheotomy. Splenic rupture, marked by sudden abdominal pain, requires splenectomy. About 20% of patients with infectious mononucleosis also have streptococcal pharyngotonsillitis and should receive antibiotic therapy for at least 10 days.

Prevention

Mononucleosis is believed to spread through saliva. If you're infected, you can help prevent spreading the virus to others by not kissing them and by not sharing food, dishes, glasses and utensils until several days after your fever has subsided and even longer, if possible.

The Epstein-Barr virus may persist in your saliva for months after the infection. If you've had mononucleosis, don't donate blood for at least six months after the onset of the illness.

There's no vaccine to prevent mononucleosis.