Climate and mammal host community characteristics drive tuberculosis maintenance at the wildlife livestock interface

Animal tuberculosis (TB) is a zoonosis maintained by various domestic and wild mammals in complex episystems. Higher competent host species richness at the community level promotes infection maintenance. Consequently, it has been proposed to go beyond the classic one- or two-host systems, where only certain species were considered maintenance hosts, to address "maintenance communities" of multiple hosts with different levels of contribution to infection maintenance. A further factor in TB epidemiology is the environment. In the Iberian Peninsula, water availability has a strong influence on TB in wildlife and livestock. However, the relative importance of any single host species, the richness and network of interactions in each community, or the environment in driving infection maintenance is unknown. We addressed this complexity using structural equation modelling (SEM), a framework to analyze complex relationships between multiple variables. We analyzed 18 multi-host communities and assessed the effects of climate (humidity), mammal diversity, and host (cattle, wild boar, and red deer) abundance and connectedness on TB prevalence in wild boar and cattle. Red deer abundance and connectedness and wild boar connectedness were positively correlated with TB prevalence in wild boar. Humidity was negatively correlated with TB prevalence in wild boar and cattle. Red deer connectedness and the diversity of the mammal community were positively correlated with TB prevalence in cattle, while wild boar abundance was negatively correlated. Through SEM, we integrated host abundance with community network parameters, mammal diversity, and climate to reveal the drivers of TB maintenance in multi-host systems. Climate effects were stronger on cattle TB than on wild boar TB and these effects were superimposed to other risk factors such as red deer abundance and host community structure. Our findings suggest that TB eradication in cattle could be particularly challenging in regions with high competent host species richness and arid climate, with implications for livestock health, economic sustainability of cattle farms, and reduction of zoonotic risk in rural areas.