Infectious Mononucleosis: Diagnosis and Treatment
- Infectious mononucleosis (IM) typically occurs between the ages of 15-24 (most often at 16-20 years).
- 90% of IM cases are caused by Epstein-Barr virus (EBV); other causes include cytomegalovirus (CMV), human herpesvirus 6 (HHV-6), human immunodeficiency virus (HIV), adenovirus, and toxoplasmosis.
- It spreads in saliva through direct contact and droplet spread.
- IM typically resolves within 2-4 weeks of onset; 20% of people will have persistent symptoms (sore throat, fatigue) at 1 month.
- Complications may include:
- splenic rupture
- airway obstruction
- hemolytic anemia.
Classic Signs and Symptoms
- Pharyngitis with tonsillar enlargement.
- Posterior and anterior cervical chain lymphadenopathy.
- Other potential signs include:
- Palatal petechiae.
- Liver Involvement: hepatomegaly, jaundice, or elevated aspartate aminotransferase (AST) and alanine aminotransferase (ALT).
- Rash: Erythematous, maculopapular, or morbilliform.
- Axillary and inguinal lymphadenopathy.
- It can be difficult to distinguish from streptococcal pharyngitis. Predictors of IM in the presence of sore throat were palatal petechiae (specificity 0.95; positive LR, 5.3), lymphadenopathy (posterior cervical, axillary, or inguinal, specificity 0.82-0.91; positive LR, 3.0-3.1), and splenomegaly (specificity 0.71-0.99; positive LR, 1.9-6.6).
- Clinical diagnosis alone may be sufficient; consider the following investigations if a definitive diagnosis is desired.
- Heterophile antibody test (Monospot test) and a CBC with diff.
- Absolute lymphocytosis ≥4×109/L, relative lymphocytosis ≥50%, and/or atypical lymphocytes ≥10%, and a positive Monospot = IM due to EBV.
- Positive hematological findings and negative Monospot: consider EBV Antibody Test.
- Patients with negatives tests are unlikely to have IM.
- EBV Antibody Test: Patients negative for anti-VCA IgM are highly unlikely to have EBV infection, and may require further testing for CMV, HHV-6, and HIV.
Other Tests to Consider
- Throat culture or rapid antigen detection test for streptococcal infection.
- Liver function test: IM due to EBV typically have transient, mildly elevated AST and ALT.
- Pregnant or high-risk patients (men who have sex with men, injection drug users, etc.) should receive initial testing for HIV, CMV, and toxoplasmosis in addition to EBV.
- False Negative Monospot: within the first week of symptom onset and if age <5 years old.
- False Positive Monospot: Autoimmune disease, toxoplasmosis, rubella, lymphoma, cytomegalovirus, and acute HIV.
- Supportive care alone: rest, hydration, and symptomatic management.
- Abstain from strenuous exercise for 3-4 weeks after symptom onset to limit risk of splenic rupture. However, splenic rupture reported to occur spontaneously.
- Patients involved in contact sports, or activities involving high intra-abdominal pressure, require longer periods of rest.
- Patients with IM presenting with upper airway obstruction often admitted to hospital or observed for several hours.
Analgesia and Antipyretics
- Topical anaesthetic lozenges (over the counter)
- Benzydamine (Tantum) Oral Gargle or similar (Prescription): How to Use Benzydamine Rinse – Oral (Source: HealthLinkBC).
- Usually 30 cc q1.5-3 hours. Gargle for 30 seconds, and then spit it out. Do not swallow.
- Often given but insufficient evidence to recommend the routine usage of glucocorticoids in the treatment of IM.
- NNT Summary: Corticosteroids for Acute Pharyngitis.
- Often single doses of either prednisolone or dexamethasone.
- prednisone 60 mg po
- prednisolone 30-60 mg po
- dexamethasone up to 10 mg, PO/IM
- An equivalent dose of IV corticosteroids may be used during the first few days of treatment if admitted.
- Insufficient evidence to recommend the use of antiviral medications (acyclovir, valacyclovir, ganciclovir, etc.) in the treatment of IM.
Quality Of Evidence?
We are highly confident that the true effect lies close to that of the estimate of the effect. There is a wide range of studies included in the analyses with no major limitations, there is little variation between studies, and the summary estimate has a narrow confidence interval.
We consider that the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. There are only a few studies and some have limitations but not major flaws, there are some variations between studies, or the confidence interval of the summary estimate is wide.
When the true effect may be substantially different from the estimate of the effect. The studies have major flaws, there is important variations between studies, of the confidence interval of the summary estimate is very wide.
Recommendations based on evidence from low to moderate quality systematic reviews and clinical reviews. Findings primarily based on expert opinion and consensus guidelines.
The purpose of this document is to provide health care professionals with key facts and recommendations for the diagnosis and treatment of patients in the emergency department. This summary was produced by the BC Emergency Medicine Network and uses the best available knowledge at the time of publication. However, healthcare professionals should continue to use their own judgment and take into consideration context, resources and other relevant factors. The BC Emergency Medicine Network is not liable for any damages, claims, liabilities, costs or obligations arising from the use of this document including loss or damages arising from any claims made by a third party. The BC Emergency Medicine Network also assumes no responsibility or liability for changes made to this document without its consent.
Last Updated Jul 12, 2021
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