These data contribute to the growing body of evidence that serological data (expressed as either a seroprevalence or seroconversion rate, and generated by either rapid or bead-based tests) reflect population-level TF prevalence, and probably provide meaningful signals about transmission intensity of ocular Ct. An empirical comparison of serological data with the parameter likely to be of pathological significance—the incidence of ocular Ct infection, determined at population level—would be exceedingly difficult to undertake. The gene discussed is TF; the disease is infection.