Mononucleosis Transmission: Contagious Period and Recovery

Infectious mononucleosis (caused by Epstein-Barr virus, EBV) is transmitted primarily through saliva ("kissing disease").

Contagious Timeline

• Incubation: 4–6 weeks (asymptomatic but virus shedding in saliva).
• Acute illness: 2–4 weeks (high viral load in saliva).
• Convalescence: Viral shedding persists for months (median 6 months; up to 18 months) at low levels.
• Latency: EBV establishes lifelong latency in B cells; intermittent asymptomatic reactivation with salivary shedding.

Key Implications

• You can catch mono from someone who had it 2 months ago—they may still shed virus.
• Transmission requires intimate saliva contact (kissing, sharing cups/utensils, toothbrushes).
• Casual contact (airborne, surfaces) does not transmit EBV efficiently.
• By adulthood, >90% are EBV-seropositive (past infection, often asymptomatic).

Prevention

• Avoid sharing saliva-contaminated items during acute illness and convalescence.
• No vaccine available.
• Good hygiene (handwashing) reduces but doesn't eliminate risk.

If you develop fever, pharyngitis, lymphadenopathy, fatigue 4–6 weeks after exposure, seek evaluation (heterophile antibody test, EBV serology).