The epidemiology of infectious mononucleosis in Northern Scotland: a decreasing incidence and winter peak.

BACKGROUND

Infection with Epstein-Barr virus (EBV) is almost ubiquitous in humans and generally occurs at two ages: infantile, which is usually asymptomatic and associated with poorer socioeconomic conditions, and adolescent, which causes infectious mononucleosis (IM) in ~25% cases. The determinants of whether the infection causes IM remain uncertain. We aimed to evaluate seasonality and temporal trends in IM.

METHODS

Data from all Monospot tests, used as a marker for IM, were collected from the Grampian population over 16 years.

RESULTS

Positive Monospot test results peaked at 17 years in females and 19 in males. Females had 16% more diagnoses, although 55% more tests. IM was ~38% more common in winter than summer. The annual rate of positive tests decreased progressively over the study period, from 174/100 000 (95% CI 171-178) in 1997 to 67/100 000 (95% CI 65-69) in 2012.

CONCLUSIONS

IM appears to be decreasing in incidence, which may be caused by changing environmental influences on immune systems. One such factor may be exposure to sunlight.Words 168.

FUNDING: The Medical Research Council and NHS Grampian-MS endowments.