How does Epstein-Barr virus infection occur?

How Epstein-Barr Virus Infection Occurs

EBV transmission occurs primarily through intimate oral contact via infected saliva, with the virus entering through the oropharyngeal mucosa to infect epithelial cells and subsequently B lymphocytes, establishing lifelong latency in the host. 1, 2

Primary Transmission Routes

Oral-Salivary Transmission (Primary Route)

• EBV spreads predominantly through saliva during intimate kissing contact, particularly among adolescents and young adults 1, 3
• The virus enters through the oropharyngeal mucosa where it initially replicates in epithelial cells 2, 4
• Following primary infection, the virus is shed in saliva for weeks, and chronic shedding continues throughout life, facilitating person-to-person transmission 2
• How preadolescent children acquire the virus remains unclear, though transmission still occurs during early childhood 3

Alternative Transmission Routes (Less Common)

• Sexual transmission is possible but not a major route, with EBV detected in 7% of cervical samples, 5% of male urethral samples, and 3% of semen samples from asymptomatic individuals 5
• The virus levels in genital secretions are significantly lower than in saliva (below 10 EBV genomes per microgram of DNA), making sexual transmission inefficient 5
• EBV can rarely spread through semen, blood transfusions, and organ transplantations 4
• The virus in genital secretions is mainly cell-associated, suggesting latent infection in B lymphocytes rather than epithelial cells 5

Cellular Infection Mechanism

Initial Infection Process

• After entering through oropharyngeal mucosa, EBV replicates in epithelial cells of the oropharynx 2, 4
• Infiltrating B lymphocytes become infected, and the virus activates normal resting B cells, resulting in immortalized B cell populations 2
• This growth program utilizes all latent viral genes and proteins 2

Viral Persistence Strategy

• EBV can shuttle between different cell types, mainly B cells and epithelial cells, and switch between latent and lytic life cycles 4
• B cells serve as the major reservoir for the virus, though other cell types (rarely NK cells and T-cells) may become infected 6, 4
• This ability to switch between cell types and life cycles enables chronic relapsing/reactivating infections 4

Clinical Context of Transmission

Age-Related Infection Patterns

• Primary infection in childhood is mostly asymptomatic 6
• Infection during adolescence or young adulthood can result in infectious mononucleosis, characterized by sore throat, cervical lymphadenopathy, fatigue, and fever lasting several weeks 3
• Over 90-95% of the human population becomes infected at some point during their lifespan 3, 6

Important Transmission Considerations in Sports/Group Settings

• Close contact is required for transmission, and endemic disease within adolescent group settings has been reported 1
• Avoidance of sharing drinking vessels, water bottles, cups, and other items that contact saliva is important in reducing infectious risk 1

Common Pitfalls

• Do not assume all transmission occurs through symptomatic individuals - chronic asymptomatic shedding in saliva is the primary mechanism of spread 2
• While sexual transmission is biologically plausible with documented shared viral isolates between sexual partners, the low viral loads in genital secretions make this a minor transmission route compared to oral contact 5
• The virus establishes lifelong latency after primary infection, meaning infected individuals can transmit the virus throughout their lifetime, not just during acute illness 2, 6