Vegetation cover and biodiversity reduce parasite infection in wild hosts across ecological levels and scales

Abstract

Land use changes and biodiversity loss critically disrupts ecosystem functioning and are major drivers of infectious disease outbreaks. Trypanosoma cruzi, the agent of Chagas disease, is a multi‐host parasite whose epidemiology has changed due to the expansion of anthropogenic activities over natural areas. We aimed to understand the ecological processes increasing parasite prevalence at the individual, the community and the landscape levels using the largest database on small mammal infection by T. cruzi in Brazil. We applied machine learning techniques and structural equation models to show that allometric traits and the relative abundance of rodents in the community were important predictors of infection risk, followed by variables associated with the landscape environmental quality. Natural vegetation cover change and the taxonomic and functional dimensions of biodiversity indirectly reduced infection through its effect on the abundance distribution and composition of host communities. According to our findings, approaches to biodiversity conservation and restoration based on the integration of social inclusion and human welfare would contribute to regulate the prevalence of T. cruzi in wild hosts, which may reduce overall transmission risk.

Host-pathogen-vector continuum in a changing landscape: Drivers ofBartonellaprevalence and evidence of historic spillover in a multi-host community

“…Small mammals, however, carry especially high numbers of pathogens [12,13] because they are disproportionately diverse within mammalian communities [14], even more so than bats. Small mammals also differ from bats in that they often increase (rather than decrease) in abundance in a modified landscape, resulting in the elevated prevalence and transmission risk of associated zoonoses in the landscape [15,16]. Small mammal densities are known to locally increase, for example, when large herbivore densities decrease [17], leading in turn to an increase in pathogen prevalence [18].…”

“…(iv) and finally, do we find evidence for spillover, detected as shared Bartonella haplotypes between members of these communities? We began with the expectation that the forest-plantation mosaic would have higher small mammal densities and Bartonella prevalence than the protected area [9,15]. We also expected that Bartonella haplotypes would be specific to host species [25] while limited spillover (vector-mediated spillover) among hosts that occupy the same habitats [26].…”

“…(iv) and finally, do we find evidence for spillover, detected as shared Bartonella haplotypes between members of these communities? We began with the expectation that the forest-plantation mosaic would have higher small mammal densities and Bartonella prevalence than the protected area [9,15].…”