Disentangling wildlife-cattle interactions in multi-host tuberculosis scenarios: systematic review and meta-analysis

Ecological interactions involving wildlife (wild mammals) and cattle Bos taurus are considered fundamental drivers of animal tuberculosis (TB) caused by Mycobacterium bovis at the wildlife-livestock interface. Despite recent insights about the role of direct and indirect interactions on TB dynamics, a mechanistic evaluation of studies addressing patterns of wildlife-cattle interaction at the global level is lacking, and the most likely factors explaining interaction rates under different epidemiological scenarios remain poorly understood. We began by reviewing the main criteria used to define a wildlife-cattle interaction relevant to Mycobacterium bovis transmission under different methodological approaches (camera-trapping, proximity loggers and Global Positioning System collars). Secondly, we applied a generic framework to estimate and characterise interaction patterns between susceptible wildlife and cattle hosts worldwide, testing the effect of potential ecological and methodological factors on interaction rates. We synthesise two main criteria to define direct interactions and five criteria to define indirect interactions between wildlife and cattle. Using data from 31 studies, our meta-analysis showed that wildlife-cattle direct interaction rates were low (mean = 0.03 interactions/month per species pair, range: 0.00-0.12). In contrast, indirect interaction rates were 154 times higher than the mean of direct interaction rates (mean = 4.63 interactions/month per species pair, range: 0.16-30.00). To prevent TB transmission to cattle, attention should be given to indirect interactions between wildlife and cattle in shared environments. Indirect interactions significantly increase with increasing wildlife density, which, hypothetically, could result in a higher TB transmission risk for cattle. We outline recommendations to achieve harmonised integration and comparison of results in future studies. Consolidation of knowledge in this field will contribute towards guiding control and biosecurity measures, also applicable to other infectious diseases at the wildlife, domestic species and human interfaces.