infectious mononucleosis [L, inficere, to stain; Gk, monos, single; L, nucleus, nut; Gk, osis, condition] , an acute herpesvirus infection caused by the Epstein-Barr virus (EBV). The disease is usually transmitted by droplet infection but is not highly or predictably contagious. Young people are most often affected. In childhood the disease is mild and usually unnoticed; the older the person, the more severe the symptoms are likely to be. Infection confers permanent immunity, although the virus continues to replicate and can be transmitted. When infection lasts more than six months it is called chronic EBV. See also Epstein-Barr virus, viral infection. ▪ OBSERVATIONS: The hallmark signs of mononucleosis are profound fatigue; a fever that peaks in the late afternoon at 101° F to 105° F (38.3° C to 40.6° C); severely painful and exudative pharyngitis; and symmetric lymphadenopathy. Splenomegaly is usually present in the second or third week. Mild hepatomegaly may also be present. A maculopapular rash, palatal petechiae, and periorbital edema are less common signs. Fatigue and general malaise may persist for months after infection clears. Diagnosis is made by the presence of clinical manifestations plus a differential WBC count showing lymphocytes and monocytes more than 50%; a heterophil agglutination antibody test with an antibody titer greater than 1:40; and an EBV-immunoglobulin M test with antibodies more than 1:80. Liver function tests (aspartate aminotransferase [AST], alanine aminotransferase [ALT], and bilirubin) will be elevated if the liver is involved. Complications are rare but include splenic rupture, anemia, Guillain-Barré syndrome, meningitis, and encephalitis. ▪ INTERVENTIONS: Treatment is supportive in nature with bed rest during the acute phase, saline throat gargles, adequate hydration; nonaspirin analgesics and antipyretics; and steroids for treating impending airway obstruction, severe thrombocytopenia or hemolytic anemia. Transfusions may be indicated for severe anemia or thrombocytopenia. Splenectomy is indicated for splenic rupture. ▪ PATIENT CARE CONSIDERATIONS: The focus is on stressing rest to prevent injury to the liver and the spleen and supportive care such as gargles to ease sore throat and antipyretics, cool cloths, and sponge baths to relieve fever. Education should stress the avoidance of heavy lifting and contact sports for at least 2 months after acute recovery to prevent injury to the spleen. Prevention is impossible as more than 95% of the adult population are carriers of the EB virus and intermittently shed the virus in their saliva.
