COMMENTS
FINDINGS:
Among infected young adults, jaundice occurs in 4%, abnormal liver function tests in 95%, and splenomegaly in 50%. [CCDM, p. 196-7] A transient thrombocytopenia is common, and a self-limited hemolytic anemia may occur. [Merck Manual, p. 1626] Some patients with mononucleosis have a mild conjunctivitis. Uveitis and Parinaud's oculoglandular conjunctivitis have also been associated with EBV infection. [Guerrant, p. 995] Uncommon findings are hemolytic anemia, cytopenia, pneumonitis, carditis, seizures, palsies, Guillain-Barre, and encephalitis; [ABX Guide] EBV is one of the rare causes of parotitis. [Cohen, p. 1637] Uncommon symptoms are abdominal discomfort (9%), cough (5%), and arthralgias (2%). [PPID, p. 1877t]
LABORATORY:
Laboratory findings include a lymphocytosis of 50% or higher, 10% or more atypical lymphocytes, abnormal liver function tests, and positive serology for Epstein-Barr antibodies (VCA and EBNA). [CCDM, p. 197] Leukocytosis (10-18K) and lymphocytosis are common. Usually 10-30% or more of lymphocytes are atypical. [ABX Guide] 90-95% of adults have EBV antibodies. About 50% of children in the US and UK have EBV seroconversion before the age of 5. [PPID, p. 1875] Common urinary findings are proteinuria and hematuria. [PPID, p. 1878-9] Children less than 5 years of age and the elderly usually do not develop heterophile antibodies. [Harrisons, p. 549]
RASHES:
Various rashes develop in 10% of cases, and a diffuse maculopapular rash may be triggered by ampicillin or amoxicillin therapy. The rash may involve the palms/soles. [ID, p. 60, 1535-9] "Earlier studies reported that most pts treated with penicillin derivatives develop a macular rash; these rashes do not represent a true penicillin allergy, nor do they occur more frequently in pts exposed to penicillin derivatives rather than other drugs." [Harrisons, p. 548] About 10% of patients have a rash that may be macular, petechial, urticarial, or erythema multiforme-like; it is usually located on the trunk and arms and is present on days 4-6 of the illness. [Cohen, p. 79]
EPIDEMIOLOGY:
The virus is transmitted by saliva from asymptomatic adults to infants and between adolescents and young adults by kissing. [Harrison ID, p. 752] About 50% of children have been infected and seroconverted by the age of 5. Infection by transfusion has been reported. [Merck Manual, p. 1625-6]
COMPLICATIONS:
Complications of mononucleosis include CNS infection, transverse myelitis, neuritis, cranial nerve palsies, splenic rupture, myocarditis, pericarditis, kidney dysfunction, and pneumonia. [ID, p. 60, 1535-9] Neurological complications include Guillain-Barre syndrome, optic neuritis, mononeuritis multiplex, and transverse myelitis. {PPID, p. 1878t] Oral hairy leukoplakia, presumed to be caused by EBV, is an early manifestation of HIV infection in adults. [Harrison ID, p. 754, 836] Patients with deficient cellular immunity may develop fever, lymphadenopathy, and GI symptoms. "EBV-associated malignancies include Burkitt's lymphoma (~90% of cases in Africa and ~15% of cases in the U.S.), anaplastic nasopharyngeal carcinoma in southern China, gastric cancer (with ~9% of these tumors positive for EBV), Hodgkin's disease (especially the mixed-cellularity type), and CNS lymphoma (especially HIV-related)." [Harrisons, p. 549) "In almost all humans, strong CD4+ and CD8+ T cell immune responses to the antigenic EBV latent-infection nuclear proteins prevent uncontrolled B cell lymphoproliferation. However, when humans are severely immunosuppressed by transplantation-associated medication, HIV infection, or genetic immunodeficiencies, EBV-induced B cell malignancies can emerge." [Harrison ID, p. 721] Epstein-Barr infections are associated with Burkitt's lymphoma, nasopharyngeal carcinoma, and possibly other malignancies (Hodgkin's disease and non-Hodgkin's lymphomas). [CCDM, p. 199-202]
DIFFERENTIAL DIAGNOSIS:
Other causes of the "mono syndrome" include cytomegalovirus, Toxoplasma gondii, hepatitis B, rubella, HIV, and adverse drug reactions. [Merck Manual, p. 1626] Other causes of atypical lymphocytes (usually less than 10% of the WBCs) are acute infections (cytomegalovirus, toxoplasmosis, HIV, rubella, mumps, other herpesviruses, and rickettsiae) and drug hypersensitivity reactions. [ID, p. 1535-9]