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About Infectious Mononucleosis

Infectious mononucleosis, also called “mono,” is a contagious disease. Epstein-Barr virus (EBV) is the most common cause of infectious mononucleosis, but other viruses can also cause this disease. It is common among teenagers and young adults, especially college students. At least 25% of teenagers and young adults who get infected with EBV will develop infectious mononucleosis.

Symptoms

Typical symptoms of infectious mononucleosis usually appear 4 to 6 weeks after you get infected with EBV. Symptoms may develop slowly and may not all occur at the same time.

These symptoms include—

Doctor examining patient
  • extreme fatigue
  • fever
  • sore throat
  • head and body aches
  • swollen lymph nodes in the neck and armpits
  • swollen liver or spleen or both
  • rash

Enlarged spleen and a swollen liver are less common symptoms. For some people, their liver or spleen or both may remain enlarged even after their fatigue ends.

Most people get better in 2 to 4 weeks; however, some people may feel fatigued for several more weeks. Occasionally, the symptoms of infectious mononucleosis can last for 6 months or longer.

Transmission

EBV is the most common cause of infectious mononucleosis, but other viruses can cause this disease. Typically, these viruses spread most commonly through bodily fluids, especially saliva. However, these viruses can also spread through blood and semen during sexual contact, blood transfusions, and organ transplantations.

Other infections that can cause infectious mononucleosis:

Prevention & Treatment

There is no vaccine to protect against infectious mononucleosis. You can help protect yourself by not kissing or sharing drinks, food, or personal items, like toothbrushes, with people who have infectious mononucleosis.

You can help relieve symptoms of infectious mononucleosis by—

  • drinking fluids to stay hydrated
  • getting plenty of rest
  • taking over-the-counter medications for pain and fever

If you have infectious mononucleosis, you should not take ampicillin or amoxicillin. Based on the severity of the symptoms, a healthcare provider may recommend treatment of specific organ systems affected by infectious mononucleosis.

Because your spleen may become enlarged as a result of infectious mononucleosis, you should avoid contact sports until you fully recover. Participating in contact sports can be strenuous and may cause the spleen to rupture.

Diagnosing Infectious Mononucleosis

Healthcare providers typically diagnose infectious mononucleosis based on symptoms.

Laboratory tests are not usually needed to diagnose infectious mononucleosis. However, specific antibody tests may be needed to identify the cause of illness in people who do not have a typical case of infectious mononucleosis.

The blood work of patients who have infectious mononucleosis due to EBV infection may show—

  • more white blood cells (lymphocytes) than normal
  • unusual looking white blood cells (atypical lymphocytes)
  • fewer than normal neutrophils or platelets
  • abnormal liver function
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