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

Abstract

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.

Figure 1

Positive Monospot tests from 1997 to 2012. Number of tests performed per year shown by grey line and right hand scale. Age-gender standardised rate shown by black line and left hand scale.

Figure 2

Total Monospot and EBV specific antibody tests performed 1997 to 2012.

Figure 3

Positive / Total Monospot IM test results from 1997 to 2012.

Figure 4

Number of positive and negative Monospot tests by age and gender.

Figure 5

Seasonality of positive Monospot tests in age groups 0–14 and 15–24 years.