Dynamic Network of Interactions in the Wildlife-Livestock Interface in Mediterranean Spain: An Epidemiological Point of View

Abstract

The correct management of diseases that are transmitted between wildlife and livestock requires a reliable estimate of the pathogen transmission rate. The calculation of this parameter is a challenge for epidemiologists, since transmission can occur through multiple pathways. The social network analysis is a widely used tool in epidemiology due to its capacity to identify individuals and communities with relevant roles for pathogen transmission. In the present work, we studied the dynamic network of interactions in a complex epidemiological scenario using information from different methodologies. In 2015, nine red deer, seven fallow deer, six wild boar and nine cattle were simultaneously monitored using GPS-GSM-Proximity collars in Doñana National Park. In addition, 16 proximity loggers were set in aggregation points. Using the social network analysis, we studied the dynamic network of interactions, including direct and indirect interactions, between individuals of different species and the potential transmission of pathogens within this network. The results show a high connection between species through indirect interactions, with a marked seasonality in the conformation of new interactions. Within the network, we differentiated four communities that included individuals of all the species. Regarding the transmission of pathogens, we observed the important role that fallow deer could be playing in the maintenance and transmission of pathogens to livestock. The present work shows the need to consider different types of methodologies in order to understand the complete functioning of the network of interactions at the wildlife/livestock interface. It also provides a methodological approach applicable to the management of shared diseases.

Long-Term Determinants of Tuberculosis in the Ungulate Host Community of Doñana National Park

“…Interestingly, we found a significant association between the presence of TBL in cattle and the prevalence of TBL in fallow deer (see Figure 6 ). Previous studies on spatiotemporal interaction patterns among wild ungulates and cattle carried out in DNP showed that the dynamics of TB transmission in this area is conditioned by environmental and habitat-related peculiarities which facilitate the spatiotemporal direct and indirect overlap between wildlife and livestock species [ 25 , 29 , 30 ] ( Figure 10 ). Interestingly, high contact rates between fallow deer and cattle have been reported in DNP [ 13 , 30 ].…”

“…However, we cannot ignore differences in exposure in a grazing species that mainly use open areas, in contrast to the more habitat generalist wild boar and red deer. In DNP, intra and interspecific contact networks, and the subsequent molecular epidemiology pattern (distribution of the M. bovis types), seems to act at a very local scale at the host community level [ 19 , 25 , 30 ]. Previous studies on molecular epidemiology of TB in DNP have suggested that a local transmission frequently occurs between species [ 19 ].…”

“…In this sense, most studies have demonstrated that cattle tend to avoid shrublands in favour of open grassland and marshland just like fallow deer, which usually graze on the meadows on the periphery of the marsh and on the marsh itself [ 43 , 61 ]. Furthermore, the gregarious habits of both species, more marked in open habitats, favour these contacts, often establishing mixed groups [ 30 , 62 , 63 ]. This finding is in agreement with Triguero-Ocaña et al [ 30 ] who recently suggested the potential substantial role of fallow deer in the maintenance and transmission of TB to livestock in DNP.…”

“…Furthermore, the gregarious habits of both species, more marked in open habitats, favour these contacts, often establishing mixed groups [ 30 , 62 , 63 ]. This finding is in agreement with Triguero-Ocaña et al [ 30 ] who recently suggested the potential substantial role of fallow deer in the maintenance and transmission of TB to livestock in DNP. In summary, the association of the presence of TBL between cattle and fallow deer is indicative of (i) sharing (in either direction) TB with cattle and/or (ii) being exposed to similar risk factors since both species are the closest ecologically speaking among the ruminants of the park (they are both grazers that prefer open lands, while red deer typically are mixed grazers/browsers).…”

“…Research in DNP has provided essential understanding on the epidemiology and ecology of TB in this diverse host community and such a complex environment [ 18 , 19 , 23 , 24 , 25 ]. Some of the previous findings regarding the spatial ecology of interactions at the wildlife–livestock interface [ 18 , 25 , 28 , 29 , 30 ], the population dynamics and the molecular epidemiology [ 14 , 23 , 24 ] are noteworthy. Research in DNP has also provided evidence of the relevance of some population and environmental factors in the transmission and maintenance of MTC [ 13 ].…”