Does cytomegalovirus infection increase the risk of tuberculosis in UK children?

There is a hypothesized association between pre-existing cytomegalovirus (CMV) infection and risk of acquiring tuberculosis (TB). We aimed to explore if CMV seroprevalence and CMV IgG levels in children were associated with TB disease or <i>Mycobacterium tuberculosis</i> (<i>Mtb</i>) infection compared with children who were exposed to TB but remained well. In this cross-sectional analysis from an observational cohort study of children exposed to TB in their household in the UK, we examined samples from 75 participants, of whom 40 (53%) were male. Median age of the cohort was 6 years (interquartile range: 3-11 years). In total, 21 (28%) children had TB disease, 27 (36%) had <i>Mtb</i> infection and 27 (36%) had TB exposure only. There was no increased risk of TB in children who were CMV-seropositive (OR 2.18 [0.75-6.48]), and there were no differences in CMV IgG quantification by TB category. There was no detectable CMV viraemia in any of the children in our study. We found higher levels of CMV seroprevalence (49%) than previously described in the UK. In this small study of children exposed to TB, in a low-TB burden setting, we found no association between CMV serostatus or CMV IgG levels and TB status.This article is part of the discussion meeting issue 'The indirect effects of cytomegalovirus infection: mechanisms and consequences'.