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Key Clinical Questions Infectious Mononucleosis

  • image What are the major complications of Epstein-Barr virus associated infectious mononucleosis (“mono”)?

  • image What other viruses cause a mononucleosis-type clinical syndrome?

  • image What are the appropriate diagnostic tests for acute Epstein-Barr virus infections?

  • image What are the current treatment recommendations for Epstein-Barr virus associated infectious mononucleosis?

Varicella-Zoster Virus
  • image What are the complications of adult varicella-zoster virus infection?

  • image What are the treatment options for varicella-zoster virus infections?

  • image What is the best way to treat postherpetic neuralgia?

  • image What are the indications for the varicella-zoster vaccine in adults?

  • image When should patients with influenza-like illness be hospitalized?

  • image How good are rapid virus diagnostic tests for influenza virus?

  • image How is influenza infection best treated with antiviral agents?

  • image What are the major complications of acute influenza?

Viruses may infect any organ system of the body, and present with common or rare clinical conditions. Viral infections may be trivial or life threatening. Any given clinical syndrome, such as pneumonia, may have a multitude of viral causes. Additionally, some viruses, such as human cytomegalovirus (CMV), have protean clinical manifestations, including pneumonitis, colitis, encephalitis, and a mononucleosis-like syndrome. This chapter will discuss three common viruses in hospitalized patients: Epstein-Barr virus (EBV), varicella-zoster virus (VZV), and influenza virus, along with their complications.



Infectious mononucleosis, often referred to as mono or kissing disease, is spread by close physical contact with infected secretions. It is most often seen in adolescents and young adults, and is not serious in most individuals. However, it can lead to significant time away from school or work, and may be associated with persistent fatigue and prolonged convalescence in some individuals.


Although other viruses produce a similar clinical syndrome, infectious mononucleosis is most often caused by acute EBV infection. Most people become infected with EBV before the age of 6 years. When EBV infection occurs early in life, it is usually asymptomatic or subclinical. Infection in young adulthood is more likely to lead to clinical mono, perhaps because of a more robust immune response. The major cell infected by EBV is the B lymphocyte; up to 20% of host B lymphocytes may be infected. Cellular immunity is heavily involved in containing EBV infection: the atypical lymphocytes seen in acute EBV infections are activated CD8+ T-cells. The humoral immune system produces antibodies directed against the virus. For unclear reasons, antibodies are also produced against unrelated antigens found on sheep and horse red cells. These antibodies are known as heterophile antibodies, and they form the basis for the mononucleosis spot (monospot) test.


Infectious mononucleosis usually presents with exudative pharyngitis, fever, and symmetrically enlarged cervical lymph nodes. Sore throat may cause severe discomfort. Tonsillitis is common; if massive, “kissing tonsils” may impinge on the airway. Fever lasts from a few days ...

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