Abstract
Understanding the effects of anthropogenic disturbance on zoonotic disease risk is both a critical conservation objective and a public health priority. Here, we evaluate the effects of multiple forms of anthropogenic disturbance across a precipitation gradient on the abundance of pathogen-infected small mammal hosts in a multi-host, multi-pathogen system in central Kenya. Our results suggest that conversion to cropland and wildlife loss alone drive systematic increases in rodent-borne pathogen prevalence, but that pastoral conversion has no such systematic effects. The effects are most likely explained both by changes in total small mammal abundance, and by changes in relative abundance of a few high-competence species, although changes in vector assemblages may also be involved. Several pathogens responded to interactions between disturbance type and climatic conditions, suggesting the potential for synergistic effects of anthropogenic disturbance and climate change on the distribution of disease risk. Overall, these results indicate that conservation can be an effective tool for reducing abundance of rodent-borne pathogens in some contexts (e.g. wildlife loss alone); however, given the strong variation in effects across disturbance types, pathogen taxa and environmental conditions, the use of conservation as public health interventions will need to be carefully tailored to specific pathogens and human contexts.This article is part of the themed issue ‘Conservation, biodiversity and infectious disease: scientific evidence and policy implications’.
Highlights
Given the burgeoning global burden of zoonotic disease [1,2,3,4] and a hypothesized protective effect of biodiversity on disease prevalence and exposure risk [5,6,7], there is growing interest in the possibility that biodiversity conservation may reduce the impacts of infectious disease on human populations [8]
Research was conducted in Laikipia County, central Kenya, because East Africa is considered to be a hotspot for emergence and re-emergence of zoonotic disease [1], and is a hotspot of mammalian diversity [45]
For three of the five pathogen taxa, we found no significant difference in the number of infected rodents between pastoral and paired conserved sites (Bartonella, Theileria and Hepatozoon)
Summary
Given the burgeoning global burden of zoonotic disease [1,2,3,4] and a hypothesized protective effect of biodiversity on disease prevalence and exposure risk [5,6,7], there is growing interest in the possibility that biodiversity conservation may reduce the impacts of infectious disease on human populations [8]. We examined the effects of large-wildlife declines [19] and the conversion of savannah habitat to both cropland and intensively used livestock pasture [20] on the ecology of five locally important rodent-borne pathogen genera; Anaplasma, Bartonella, Theileria, Borrelia and Hepatozoon. Many taxa of these pathogens are regionally important to livestock, wildlife and human health [21,22,23,24]. We build on this work to test the importance of the climate gradient in driving changes in abundance of infected animals, and to assess whether local climate conditions interact with disturbance to change the magnitude or even direction of the effect of disturbance on pathogen prevalence
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