Abstract

The number of cattle herds placed under movement restrictions in Great Britain (GB) due to the suspected presence of bovine tuberculosis (bTB) has progressively increased over the past 25 years despite an intensive and costly test-and-slaughter control programme. Around 38% of herds in GB that clear movement restrictions will experience a recurrent incident within 24 months. A major risk factor for a herd being diagnosed with bTB is previous disease in that herd; yet the relative contributions due to within-herd persistence and re-introduction from outside the herd have not been determined. Here, we apply epidemiological models parameterised from VetNet data to infer the contribution of missed infection to the observed empirical patterns of within-herd persistence of bTB in GB. Our best fitting model, that is most consistent with experimental evidence, estimates that the probability of infection remaining after a herd has been declared “bTB free” increases with herd size, up to a maximum of ~15%. However, the impact of missed infection is very small compared to the extrinsic rate of transmission into the herd. As a consequence, while ongoing efforts to improve current imperfect diagnostic tests may be able to reduce the duration of bTB breakdowns, they are unlikely to reduce recurrence unless the sources of extrinsic transmission into herds are simultaneously addressed.