Incubation Period for Infectious Mononucleosis
The incubation period for infectious mononucleosis (mono) after exposure to Epstein-Barr virus is typically 4 to 7 weeks, with symptoms beginning to appear after this latency period. 1
Timeline of EBV Infection
The incubation period ranges from approximately 4 to 7 weeks (up to 7 weeks) after initial exposure to EBV before symptoms develop. 1
After this incubation period, the first signs of symptomatic infection include sore throat, mild fever, and swollen lymph nodes in the neck area. 1
The classic triad of fever, tonsillar pharyngitis, and lymphadenopathy appears after the incubation period is complete. 2
When Diagnostic Testing Becomes Positive
Heterophile antibodies (Monospot test) typically become detectable between days 6-10 after symptom onset, not after exposure. 3 This means testing during the first week of symptoms has a 25% false-negative rate. 4
Heterophile antibodies peak during weeks 2-3 of illness. 3
VCA IgM antibodies indicate acute/recent infection and develop early in the symptomatic phase. 3
EBNA antibodies develop 1-2 months after primary infection begins and persist for life, making them useful for distinguishing recent from past infection. 3, 5
Clinical Presentation Timeline
Symptoms usually subside after a few weeks, though protracted courses can occur. 1
Fatigue may be profound but tends to resolve within three months. 2
Peripheral blood leukocytosis with atypical lymphocytes (>10% of total lymphocyte count) is observed during the symptomatic phase. 2
Important Clinical Caveat
- Primary EBV infection in children up to 10 years is usually asymptomatic or shows nonspecific courses, whereas adolescents and young adults (ages 15-24) are most likely to develop symptomatic infectious mononucleosis. 1, 4 This explains why the clinical syndrome is predominantly seen in teenagers and young adults despite widespread childhood exposure to the virus.