Mononucleosis
Christopher McGrew
BasicsDescription
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Acute viral syndrome classically resulting from infection with the Epstein-Barr virus (EBV)
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EBV is a lymphotrophic γ-herpesvirus that replicates in epithelial cells and B lymphocytes.
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Characterized by classic triad of fever, pharyngitis, and lymphadenopathy
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Synonym(s): “Mono”; Glandular fever
Epidemiology
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Peak incidence in the U.S. is between the ages of 15 and 19
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Estimated prevalence 1–3% of adolescent/young adult population. U.S. incidence is 45:100,000.
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Evidence of infection via EBV antibody seroconversion occurs earlier in lower socioeconomic groups.
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In all populations, >90% seroconversion by the end of the 3rd decade of life, although many are not aware of having the disease.
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No evidence to suggest that infectious mononucleosis is more or less prevalent in student athletes than among the general student population.
Risk Factors
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Transmission via passage of infected mucous membrane secretions, most commonly saliva (“the kissing disease”); incubation period typically 30–50 days
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EBV also felt to be passed via respiratory tract secretions, blood, rectal, and potentially genital secretions, raising the possibility of sexual transmission. No aerosol transmission has been found.
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Lack of mononucleosis epidemics supports concept of low-level contagiousness.
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Relative risk of contracting EBV increased by factors negatively affecting the overall status of the immune system: Baseline fatigue, overtraining, poor nutritional status
General Prevention
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General handwashing/hygiene measures
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Avoidance of sharing of water bottles, food, other utensils
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Proper rest/avoid overtraining
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Good nutrition
Etiology
Infectious mononucleosis (IM) is caused by the EBV, which is a lymphotrophic γ-herpesvirus that replicates in epithelial cells and B lymphocytes.
Commonly Associated Conditions
Group A beta hemolytic streptococcal pharyngeal/tonsillar infection coexistent in up to 30% of cases
Diagnosis-
IM remains a clinical diagnosis based on history, physical, and selected laboratory testing.
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Hoagland's criteria are frequently cited for establishing diagnosis
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CBC shows at least 50% lymphocytes, of which 10% are atypical.
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Presence of fever, pharyngitis, and adenopathy
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Serologic confirmation
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Only 50% of patients with suggestive symptoms and serologic confirmation meet all of Hoagland's criteria.
History
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Prodrome of malaise/fatigue followed by development of the classic triad of fever, sore throat, and enlarged lymph nodes
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Headache in many cases
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Patient often does not have known history of EBV exposure.
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Athlete may complain of poor exercise performance.
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Fatigue is often disabling, even for activities of daily living.
Physical Exam
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Classic triad: Fever, pharyngitis, and cervical lymphadenopathy (anterior and posterior)
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Many patients manifest a prodrome of disabling fatigue/malaise.
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Pharyngitis characterized by yellow-gray tonsillar exudate and palatal edema
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Fevers of 39°–40°C with evening peaks, typically for 10–14 days
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Abdominal pain
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Notable decline in exercise tolerance
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Fever often demonstrable
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Patient may appear fatigued and mildly to moderately ill but generally nontoxic.
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Exudative pharyngitis
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Palatal petechiae
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Periorbital edema
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Prominent anterior and posterior cervical lymphadenopathy (lymphadenopathy may also involve axillary and inguinal regions)
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Although splenomegaly is probably present in nearly all patients, peaking in the 2nd and 3rd wks, physical exam for splenomegaly has poor sensitivity and specificity, and interexaminer reliability is poor.
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Overzealous abdominal exam may precipitate splenic injury in rare cases.
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With splenic rupture, may develop Kehr sign (patient supine, raise left leg, intra-abdominal blood tracks up to diaphragm, creates referred pain to left shoulder)
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Maculopapular, urticarial or petechial rash (petechial rashes should raise suspicion for potential aplastic anemia, thrombocytopenia or DIC)
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Maculopapular rash may often develop after antimicrobial administration: Most commonly ampicillin or amoxicillin, but has also been reported with the use of azithromycin, levofloxacin, and cephalexin.
Diagnostic Tests & Interpretation
Lab
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Primary means of laboratory testing via nonspecific heterophile antibody studies (ie, monospot qualitative agglutination slide test)
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Heterophile antibody (+) 60–70% at 1 wk, 80–90% by 3–4 wks
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Definitive diagnosis: EBV viral capsid antigen (VCA) immunoglobulin M (+) for acute infections, (-) for recent or past infections
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EBV VCA immunoglobulin G confirms past infection and generation of protective antibody.
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May use more specific EBV-associated antigens if necessary to determine exact phase of illness
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Classic hematologic findings include >10% atypical lymphocytes [Downey cell-activated cytotoxic suppressor (CD8) T lymphocytes], relative leukocytosis (up to 20,000), followed by mild neutropenia during wk 2 of illness, mild hemolytic anemia, and mild thrombocytopenia (100,000–140,000/mm3)
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Mild hepatitis (2–3-fold increase in liver function tests) may be seen in week 2–3 of illness.
Imaging
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No routine imaging used for diagnosis or management of mononucleosis
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One-time imaging of the spleen for assessment of splenomegaly at the time of illness is not recommended because of the wide variability encountered in normal values (1)[A].
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Contrasted abdominal CT for concerns about splenic rupture (incidence of 1–2 per 1,000 cases of mononucleosis, often spontaneous)
P.395
Differential Diagnosis
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Primarily must be differentiated from nonspecific viral syndromes, lymphoma, leukemia, and Streptococcus pharyngitis
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Many infectious agents may cause mononucleosis-like syndromes: Cytomegalovirus, adenovirus, hepatitis A, human herpesvirus 6, HIV, rubella, toxoplasmosis
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Medications causing mononucleosis-like syndromes: phenytoin, sulfa drugs
TreatmentAdditional Treatment
General Measures
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Care is primarily supportive/symptomatic.
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No effective treatment presently is available.
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Care should be taken to avoid splenic trauma; avoid exercise and activities with jarring movements; use stool softeners to avoid increasing intra-abdominal pressure.
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Avoid alcohol and other liver toxins.
Referral
Splenic rupture
Additional Therapies
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Acyclovir has been shown to decrease viral shedding, but has no effect on the natural course of the illness, and no clinical benefit has been demonstrated.
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Corticosteroids may be clinically indicated in cases with airway compromise, severe dysphagia, massive/painful spleen enlargement, myocarditis, or hemolytic anemia.
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A Cochrane Review evaluating the use of corticosteroids for symptom control in IM concluded that although symptoms were decreased for the 1st 12 hr, these benefits were lost at 2–4 days. Since there was no clear evidence on the effectiveness of steroids and, given the potential for adverse effects from the use of steroids, the Cochrane Review recommended that corticosteroid use be avoided in uncomplicated cases (2)[A].
Complementary and Alternative Medicine
None
Surgery/Other Procedures
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Splenic rupture may be treated with either splenectomy or observation in selected situations.
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Earlier return to play with splenectomy, but must be weighed against risks of asplenia
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If splenectomy chosen, H flu, pneumococcal, and meningococcal vaccination should be provided prior to splenectomy
Ongoing CareDiet
No special recommendations other than balanced diet with adequate fluids and fiber to avoid constipation; avoid alcohol.
Prognosis
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Most patients who contract IM have an uneventful clinical course with an unremarkable recovery.
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Some athletes may take as long as 3 mos to return to their pre-illness levels of activity.
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Adult form of mononucleosis is different from the disease in children and adolescents:
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Most adults: Pharyngitis or lymphadenopathy
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Fever is often more prolonged.
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Abnormal liver function more frequent
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Lymphocytosis/presence of atypical lymphocytes less common
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Complications
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A wide variety of complications can occur, involving virtually all organ systems:
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Edema of Waldeyer's ring, resulting in airway compromise and/or severe dysphagia
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Splenomegaly: Nearly universal in IM, so not truly a complication
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Splenic rupture: Reported in 0.1–2% of cases; most cases occur in 1st 3–4 wks of illness; in 1 study, 50% nontraumatic
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Guillain-Barré syndrome
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Cranial nerve palsies
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Aseptic meningitis
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Meningoencephalitis
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Aplastic anemia
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Hemolytic-uremic syndrome
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Disseminated intravascular coagulation
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Jaundice
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Myocarditis
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Conjecture that chronic fatigue syndrome may be associated with chronic EBV infection is not well supported in the literature.
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Immunocompromised (eg, HIV, transplant patients, etc.): Lymphoma and other lymphoproliferative disorders are potential severe complications.
References
1. Hosey RG, Mattacola CG, Kriss V, et al. Ultrasound assessment of spleen size in collegiate athletes. Br J Sports Med. 2006;40:251–254.
2. Candy B, Hotopf M. Steroids for symptom control in infectious mononucleosis. Cochrane Database Syst Rev. 2006;3:CD004402.
3. Putukian M, O'Connor FG, Stricker P, et al. Mononucleosis and athletic participation: an evidence-based subject review. Clin J Sport Med. 2008;18:309–315.
Additional Reading
Peter J, Ray CG. Infectious mononucleosis. Pediatr Rev. 1998;19:276–279.
CodesICD9
075 Infectious mononucleosis
Clinical Pearls
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In most cases, athletes will not feel well enough to participate in activity for several weeks. In addition, although the risk for splenic rupture is extremely low, given that most of these occur within the 1st 3 wks of illness, independent of spleen size, it is generally felt that it is safe to resume light activity 3 wks from the onset of symptoms, as long as the athlete is afebrile, has a good energy level, and does not have any significant associated abnormalities. The risk of splenic rupture likely diminishes as more time progresses; therefore, delaying return to play should be considered if clinical features, lack of athlete readiness, and/or associated complications are present. Treatment must, therefore, be individualized to account for all of these issues (3)[C].
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The appropriate time for safe return to contact play is unclear, although, given the risk for splenic rupture, a time frame of at least 3 wks commonly is recommended. Return can occur only after the athlete has no remaining clinical symptoms, is afebrile, and has a normal energy level. The risk for splenic rupture likely decreases as more time passes, allowing for individualized return-to-play decisions, depending on the athlete, sport, and other factors (3)[C].
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It is unclear what role exercise has on the natural history of IM disease. Although many athletes can self-regulate on return to ad lib activity if afebrile, it would appear that premature return to heavy exertion might prolong the duration of symptoms, most notably fatigue, and also be associated with a decrease in performance (3)[C].
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Fortunately, because of the nature of transmission, epidemics of mononucleosis are uncommon. Care should be taken to avoid shared water bottles, utensils, etc. Teams that travel extensively together have greater potential contacts for transmission. As the incubation period is lengthy, identifying index cases is difficult. It is not practical or necessary to exclude infected teammates if appropriate measures are taken to avoid spread of the virus. Appropriate rest, proper nutrition, and avoiding overtraining may reduce susceptibility to IM.