What is the risk of transmitting infectious mononucleosis (mono) to others?

Risk of Transmitting Infectious Mononucleosis (Mono)

The primary risk of transmitting infectious mononucleosis occurs through close personal contact with saliva from an infected person, with transmission via blood and respiratory droplets also possible but less common. 1

Transmission Routes

• Infectious mononucleosis is caused by the Epstein-Barr virus (EBV), which is primarily transmitted through saliva (commonly called the "kissing disease"), making intimate oral contact the main route of transmission 2, 1
• Secondary transmission routes include blood exposure and respiratory droplets, though these are less common 2
• The virus can remain in saliva for months after infection, creating an extended period of potential transmission 1
• Transmission through sharing of drinking vessels, eating utensils, or other items that may have saliva contact is possible 3

Transmission Risk Factors

• The highest risk period for transmission is during the acute phase of illness when viral shedding is greatest 1
• Adolescents and young adults (15-24 years) have the highest incidence of symptomatic infectious mononucleosis 1
• Close, prolonged contact increases transmission risk, similar to other respiratory and saliva-transmitted infections 3
• Contaminated hands can serve as vectors for indirect transmission, highlighting the importance of hand hygiene 3

Incubation Period and Infectivity

• The incubation period for infectious mononucleosis ranges from 4 to 7 weeks, during which transmission may occur before symptoms appear 2
• Infected individuals can continue shedding the virus in saliva for months after symptoms resolve, though infectivity generally decreases over time 1, 4
• Unlike some other infections, EBV can be transmitted even when the infected person is asymptomatic 4

Prevention Strategies

• Avoid sharing drinking vessels, eating utensils, and other items that may have saliva contact 3
• Practice good hand hygiene, especially after potential contact with saliva 3
• Avoid close contact (kissing, sharing drinks) with individuals known to have active mono 1
• In sports settings, follow standard precautions for blood exposure if bleeding occurs 3
• There is currently no vaccine available for EBV/infectious mononucleosis 2

Special Considerations

• Most adults (>90%) worldwide have been infected with EBV and carry the virus, though most infections in children under 10 years are asymptomatic or have nonspecific symptoms 2, 4
• Immunocompromised individuals are at higher risk for severe disease and complications if they contract EBV 1
• Athletes with active infectious mononucleosis should avoid contact sports for at least three weeks from symptom onset due to risk of splenic rupture, which is a potentially fatal complication 1, 5

While infectious mononucleosis is generally self-limiting in immunocompetent individuals, awareness of transmission routes and preventive measures can help reduce spread, particularly in settings with close personal contact such as schools, colleges, and sports environments 1, 4.