SEARCH RESULTS FOR: Acute-Infectious-Mononucleosis

Acute Infectious Mononucleosis

**See corresponding Calgary Guide slides Legend: Acute Infectious Mononucleosis: Pathogenesis & clinical findings Viral transmission (Epstein-Barr virus (EBV), Cytomegalovirus (CMV), human immunodeficiency virus (HIV), etc) through saliva (most commonly in adolescents & young adults aged 15-24) Virus infects epithelial cells of the oropharynx Virus infects & immortalizes circulating B lymphocytes Virus replicates in infected B-cells Immune cell proliferation in lymphatic system (primarily lymph nodes & spleen) Infected B-cells enter systemic circulation Systemic inflammatory response activated Inflammation & edema of sinuses Bilateral periorbital &/or palpebral edema Pharyngitis** (often with grey/white exudative secretions) Palatal petechiae Blood vessel damage in the soft palate Edema of soft palate & tonsils Airway obstruction ↑ Immunoglobulin M (IgM) antibodies to EBV viral capsid antigen (VCA) Positive IgM-VCA Immortalized B-cells produce ↑ antibodies Production of heterophile antibodies (weakly reactive & non-specific) Positive monospot (heterophile antibody) test (↓ sensitivity in children <4 years) Virus may remain dormant in B-cells Latent infection with periodic reactivation Generalized lymphadenopathy (enlarged lymph nodes) Massive cervical, mediastinal or hilar lymphadenopathy Posterior cervical lymphadenopathy Platelets sequestered (trapped) within spleen & overactive spleen (hypersplenism) discards ↑ platelets Thrombocytopenia (↓ platelets) Weak reticular tissue in the spleen stretches Splenomegaly Splenic rupture & becomes more susceptible to injury Inflammatory response ↑ energy demand Fatigue Longstanding impacts from unknown mechanism Chronic Fatigue Syndrome Inflammatory cytokines released into circulation ↑ Thermo-regulatory set-point at hypothalamus Fever Lymphocytosis (↑ lymphocytes) (markedly CD8+ T-cells & NK cells) Immune cells infiltrate the liver Hepatomegaly ↑ Aminotransferases Leukocytosis (↑ leukocytes) CD8+ T-cells & NK cells indirectly damage hepatocytes ↑ Bilirubin & jaundice** Systemic immune response &/or antibiotic hypersensitivity reaction CD8+ T-cells respond to virus Atypical lymphocytes on blood smear Generalized maculopapular rash Authors: Ayden Hansen, Griselle Leon Reviewers: Charissa Chen, Emily J. Doucette Danielle Nelson* * MD at time of publication Published Sept 3, 2015; updated Apr 22, 2025 on www.thecalgaryguide.com Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications