Sex differences in campylobacteriosis incidence rates at different ages - a seven country, multi-year, meta-analysis. A potential mechanism for the infection.
Abstract Background There is evidence that females mount a more efficient immune response to gram-negative bacteria. The objectives of this study were to determine whether there are consistent sex differences in the incidence rates of campylobacteriosis at different ages in different countries.Methods We obtained data on incidence rates of campylobacteriosis by sex and age group over a period of 11-26 years from seven countries Male to female incidence rate ratios (IRR) were computed by age group, country and time period. For each age group, we used meta-analytic methods to combine the IRRs. Sensitivity analysis was used to test whether the results are stable and robust. Meta-regression was conducted to the estimate the effects of age, country, and time period on the IRR.Results In the age groups <1, 1-4, 5-9, 10-14, 15-44, 45-64 and 65+ years old, the pooled IRRs (with 95% CI) were 1.31 (1.26-1.37), 1.34 (1.31-1.37), 1.35 (1.32-1.38), and 1.73 (1.68-1.79), 1.10 (1.08-1.12), 1.19(1.17-1.21), 1.27 (1.24-1.30), respectively. For each age group, the excess campylobacteriosis incidence rates in males is remarkably consistent for countries and time-periods, and in meta-regression analysis, age group was responsible for almost all the variation in the IRRs.Conclusions The male predominance in campylobacteriosis incidence rates starts in infancy. This suggests that this is due, at least in part, to physiological or genetic differences and not just behavioural factors. These findings can provide clues to the mechanisms of the infection, and could lead to more targeted treatments and vaccine development.