Infectious Mononucleosis or Glandular Fever Revisited

Infectious mononucleosis is also known as kissing disease or Pfeiffer’s disease. It is caused by the Epstein-Barr virus, a type of Herpes virus.

More than 95% of adults worldwide have been exposed to this virus [1] and may be at risk of reactivation in case of immune depression, advanced HIV infection [2], treatment of inflammatory diseases with anti-TNF (tumor necrosis factor) [3] or immunosuppressive agents.

In children, the disease is asymptomatic, or it can be characterized by a flu-like syndrome, and it is thought to be more prevalent in developing rather than developed countries [1].

The symptomatic form of disease is commonly seen in teenagers who present with a sore throat, tonsillitis, lymphadenopathy, fever and fatigue. Classic symptoms also include petechiae, pharyngitis, splenomegaly and hepatitis. Thrombocytopenia and even pancytopenia may be present, as well as a cold agglutinin disease characterized by an autoimmune hemolytic anemia. Elevated hepatic transaminases can be found in roughly half of the patients. Ampicillin or amoxicillin may trigger a characteristic rash.

The Epstein-Barr virus is spread via saliva, with an incubation period of 4 to 6 weeks and symptoms lasting for 2 to 3 weeks.

The virus replicates in the endothelial cells of the pharynx and in the B cells (CD 21) [1]. This results in atypical lymphocytes or Downey cells.

The diagnosis relies on atypical lymphocytes which resemble monocytes or on heterophile antibody tests which assess agglutination with sheep, guinea pig and horse red cells. A more sensitive test is the detection of IgG (reflecting a past infection) and IgM antibodies (suggesting a recent or current infection).

Differential diagnoses can include Toxoplasma gondii or cytomegalovirus infection, bacterial tonsillitis, other causes of hepatitis, leukemia and influenza.

Treatment is symptomatic and most cases resolve spontaneously but splenic rupture can occur, although rarely. For this reason, contact sports should be avoided.

The mainstay of treatment includes non-steroidal anti-inflammatory drugs, especially ibuprofen. Antibiotics should not be used, as the etiological agent is a virus, or unless there is a concomitant streptococcal sore throat (in this case a penicillin derivative can be used).

In the event of an upper airways obstruction, steroids may be used, but opioid analgesics are relatively contraindicated due to the risk of respiratory depression.