Disease-relevant interactions between Mycobacterium bovis wildlife hosts and cattle: a systematic review and a meta-analysis

Abstract

Animal tuberculosis (TB) affects livestock and wildlife, having economic and animal health implications. Current knowledge postulates that Mycobacterium bovis maintenance and spread to other species is largely driven by interactions between cattle and wildlife. Despite recent insights about the role of direct and indirect interactions on TB dynamics at the wildlife-livestock interface, standardization of experimental approaches and data interpretation is lacking, which hampers inferences on the underlying transmission processes. Here, we seeked to examine global patterns of interactions between M. bovis wildlife hosts and cattle worldwide We began by systematically reviewing the different concepts essential to the study of interactions and revised the methodological approaches currently used to shed light on the ecological processes behind M. bovis transmission. Then, a meta-analysis of studies that have quantified interspecific interactions between wildlife and cattle was performed through a literature search on ISI’s Web of Science. Additionally, relevant literature cited there was also screened. We used generalized linear mixed models to investigate the relative importance of direct and indirect interactions, while accounting for the effect of potential ecological and methodological sources of variation. We found four definitions used to evaluate indirect interactions between wildlife hosts of M. bovis and cattle using camera trapping, proximity and gps collars; and two definitions used to assess direct interactions encompassing camera trapping and proximity collars. Global estimates of direct interactions were low and even a rare. On the opposite, indirect interactions frequencies were higher, with the mean estimated frequency representing 78.4 times more than the mean of direct interactions. Although we found no evidence for a significant effect of method type, species-traits, and landscape context on the frequencies of interactions, our results suggest that certain species (wild boar and badgers) are more likely to interact with cattle, particularly during warmer periods and at sites near water sources. Indirect interactions in shared environments might be a concern for TB transmission. The lack of scientific evidence on this topic along with complex ecological and methodological factors still limits drawing conclusions on general impacts and the source of interactions patterns at the wildlife-cattle interface.