Can biosecurity on farms reduce bovine tuberculosis risks in cattle in England? A review of observational and literature-based evidence

Background: Bovine tuberculosis (TB) is a burden to cattle farming in Great Britain. Poor biosecurity has been identified as contributing to the epidemic. Methods: We conducted a systematic review of epidemiological studies published in the scientific literature between 1921 and 2024 that measured the association between farm biosecurity and cattle TB. Eligible studies controlled for confounding factors and reported statistically significant association/s between biosecurity and TB (p < 0.05) and/or an effect ratio/s of more than 3. Biosecurity uptake in England was assessed using official Disease Report Forms (DRFs) from 4074 TB incidents occurring in 2018 and 2019. Results: Thirty-three papers with 116 effect estimates met the inclusion criteria and were grouped according to a five-point biosecurity plan. There was consistent evidence for TB risk being reduced by reducing contact with neighbouring herds and preventing cattle at higher TB risk from entering herds. The evidence for the effectiveness of measures for reducing contact between badgers and cattle was inconsistent. The DRF data showed a low uptake of biosecurity to reduce contact between badgers and cattle. Limitations: All the studies identified were retrospective. Biosecurity was measured using different instruments, for example, questionnaires. Conclusions: There is analytical epidemiological evidence supporting guidance for improving biosecurity, but there are some limitations. Further research is needed to identify the most effective wildlife-focused measures.