What is the primary mode of transmission for infectious mononucleosis?

Primary Transmission of Infectious Mononucleosis

Infectious mononucleosis is primarily transmitted through saliva, most commonly through intimate oral contact. 1, 2

Transmission Routes

• Epstein-Barr virus (EBV), the causative agent of infectious mononucleosis, is spread primarily through saliva exchange, often referred to as "the kissing disease" 1
• Close personal contact with infected individuals is the main route of transmission, particularly among adolescents and young adults 2
• Sharing of items contaminated with saliva can also lead to transmission 3
• While less common, transmission via blood and respiratory droplets can also occur 4
• Risk factors include close community contact and crowded settings, which facilitate transmission 3

Epidemiology and Population at Risk

• Infectious mononucleosis most commonly affects adolescents and young adults aged 15-24 years 1, 2
• At least 90% of adults worldwide are seropositive for EBV, indicating prior infection 4
• The mode of transmission in preadolescents is less well understood, as primary EBV infection in children under 10 years is usually asymptomatic 5, 4
• The incubation period ranges up to seven weeks after exposure before symptoms appear 4

Clinical Manifestations

• The classic triad of infectious mononucleosis includes fever, tonsillar pharyngitis, and lymphadenopathy 1, 6
• Additional common symptoms include:
  • Fatigue, which may be profound and last up to three months 1
  • Periorbital/palpebral edema (in approximately one-third of patients) 1
  • Splenomegaly (50% of cases) and hepatomegaly (10% of cases) 1
  • Maculopapular rash in 10-45% of cases 1

Diagnostic Approach

• Heterophile antibody test (Monospot) is the most widely used initial test, becoming positive between the sixth and tenth day after symptom onset 7, 8
• EBV serologic testing is recommended when clinical suspicion remains high despite a negative heterophile test 7
• False-negative heterophile results are common early in infection and in children under 10 years 8
• Laboratory findings typically include lymphocytosis with atypical lymphocytes constituting more than 10% of the total lymphocyte count 1, 6

Prevention Considerations

• Avoiding exposure to EBV is challenging due to its widespread prevalence 1
• Hand hygiene is essential during outbreaks of infectious diseases 3
• Currently, no vaccine is available for EBV prevention 4
• Avoiding sharing of personal items that may contain saliva can help reduce transmission risk 3

Important Caveats

• Immunocompromised patients have an increased risk of severe disease and lymphoproliferative disorders 8
• Spontaneous splenic rupture occurs in 0.1-0.5% of patients and is potentially life-threatening 1
• Patients should avoid contact sports or strenuous exercise for at least 8 weeks or while splenomegaly is present to prevent splenic rupture 1, 2
• EBV infection has been linked to certain cancers and autoimmune diseases as long-term sequelae 2