What causes infectious mononucleosis (mono) and how is it transmitted?

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What Causes Mono and How Is It Transmitted

Infectious mononucleosis is caused primarily by Epstein-Barr virus (EBV) and is transmitted through saliva via close personal contact, particularly through sharing saliva-contaminated items like drinking vessels, water bottles, and cups. 1, 2

Causative Pathogen

  • Epstein-Barr virus (EBV), a member of the herpes virus family, is the primary cause of infectious mononucleosis. 1, 3
  • Other pathogens can produce similar mononucleosis syndromes, including cytomegalovirus (CMV), Toxoplasma gondii, and acute HIV infection, though these are less common. 1
  • EBV is a double-stranded DNA virus that infects at least 90% of the population worldwide. 4, 5

Transmission Routes

The virus spreads primarily through saliva, earning it the colloquial name "kissing disease." 3, 6

Primary Transmission Mechanisms:

  • Close personal contact with infected individuals, particularly exposure to their saliva, is the main route of transmission. 6
  • Sharing items contaminated with saliva facilitates spread, including water bottles, drinking vessels, ladles, cups, and mouth guards. 7, 2
  • The virus can also be transmitted through blood and respiratory droplets, though these are less common routes. 4

Risk Factors for Transmission:

  • Close community contact and crowded settings facilitate transmission. 2
  • The disease most commonly affects adolescents and young adults aged 15 to 24 years through intimate oral contact. 3, 5, 6
  • How preadolescent children acquire the virus remains unclear, though primary infection in children under 10 years is usually asymptomatic. 5, 4

Prevention Strategies

Avoiding sharing of personal items that may contain saliva is the most practical prevention measure. 2

Specific Prevention Recommendations:

  • Do not share drinking vessels, water bottles, cups, or ladles. 7
  • Avoid sharing mouth guards, towels, personal protective equipment, and other items that contact saliva. 7
  • Hand hygiene is essential during outbreaks of infectious diseases. 2
  • Regular cleaning of facilities and equipment in group settings (athletic programs, schools) reduces transmission risk. 7

Important Caveat:

  • Since avoiding exposure to EBV is almost impossible given its ubiquity, the most effective long-term prevention would be development of an effective vaccine, which is not currently available. 3, 4
  • In the case of EBV infection, close contact is required for transmission, and endemic disease within adolescent group settings has been reported. 7

Special Populations at Risk

  • Immunocompromised patients have an increased risk of severe disease and lymphoproliferative disorders. 2
  • There have been no validated reports of EBV transmission through bloodborne pathogen exposure during athletic competitions, despite biological plausibility. 7

References

Guideline

Mononucleosis Causes and Diagnosis

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

Guideline

Primary Transmission of Infectious Mononucleosis

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2025

Research

Infectious Mononucleosis: An Updated Review.

Current pediatric reviews, 2024

Research

[Infectious mononucleosis--a "childhood disease" of great medical concern].

Medizinische Monatsschrift fur Pharmazeuten, 2013

Research

Infectious Mononucleosis.

Current topics in microbiology and immunology, 2015

Research

Infectious Mononucleosis: Rapid Evidence Review.

American family physician, 2023

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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