How animal behaviour influences indirect exposure risk to tuberculosis in Mediterranean ecosystems

Abstract

Animal tuberculosis, caused by bacteria of the Mycobacterium tuberculosis complex (MTBC), poses major economic and socio-ecological challenges in Europe. In Mediterranean ecosystems, water scarcity constrains host movements and resource use, shaping complex pathogen transmission dynamics at wildlife-cattle interfaces. Integrating animal behaviour with activity patterns may provide insights into host use of shared environments and potential exposure pathways. Using camera trapping, we investigated how wildlife and cattle behaviour relate to potential environment-mediated MTBC exposure in a Mediterranean multi-host landscape in the southwestern Iberian Peninsula. We quantified wildlife-cattle diel activity overlap and examined how water availability, habitat type, tree density, and season influence behaviours relevant to environmental exposure. We also assessed whether the occurrence of these behaviours was associated with spatial variation in environmental MTBC DNA concentration. Red deer showed the highest activity overlap with cattle, predominantly in forested areas away from water, and during the wet season (Dhat4 = 0.73). Behaviours potentially relevant to environmental exposure were most prevalent in red deer and least frequent in red foxes. Foraging dominated observations across species, drinking was common in cattle, red deer, and wild boar, and wallowing was largely restricted to red deer. Foraging occurred more frequently near water across wild species, while cattle foraged more frequently in areas with denser canopy cover and during the dry season. Environmental MTBC DNA concentration showed a marginal positive association with red deer foraging, whereas wallowing was less likely at sites with higher MTBC DNA loads. No significant associations were detected between environmental MTBC concentration and behaviour in the other species. Our findings show that behavioural patterns with shared environments provide complementary information to temporal activity overlap when assessing potential MTBC exposure. Accounting for behavioural and environmental context can help identify species, habitats, and behaviours that warrant greater attention in TB surveillance and management, while distinguishing potential exposure pathways from demonstrated transmission.