Epidemiological connectivity between humans and animals across an urban landscape

Abstract

Urbanization is predicted to be a key driver of disease emergence through human exposure to novel, animal-borne pathogens. However, while we suspect that urban landscapes are primed to expose people to novel animal-borne diseases, evidence for the mechanisms by which this occurs is lacking. To address this, we studied how bacterial genes are shared between wild animals, livestock, and humans (n = 1,428) across Nairobi, Kenya—one of the world’s most rapidly developing cities. Applying a multilayer network framework, we show that low biodiversity (of both natural habitat and vertebrate wildlife communities), coupled with livestock management practices and more densely populated urban environments, promotes sharing of Escherichia coli –borne bacterial mobile genetic elements between animals and humans. These results provide empirical support for hypotheses linking resource provision, the biological simplification of urban landscapes, and human and livestock demography to urban dynamics of cross-species pathogen transmission at a landscape scale. Urban areas where high densities of people and livestock live in close association with synanthropes (species such as rodents that are more competent reservoirs for zoonotic pathogens) should be prioritized for disease surveillance and control.

The City as an Evolutionary Hothouse—The Search for Rapid Evolution in Urban Settings

“…Indeed, urban-adapted mammals are known to carry more zoonoses than non-urban taxa [134]. Thus, urbanization can be a key driver of disease emergence through human exposure to novel, animal-borne pathogens under conditions of high human and commensal densities and close, frequent contact with a variety of potential hosts [133,135]. However, the transmission of parasites from wild animals to humans and domestic animals in urban and peri-urban environments is not well understood [136].…”

Antimicrobial resistance (AMR) as a form of human–wildlife conflict: Why and how nondomesticated species should be incorporated into AMR guidance

“…Additionally, if resistant genes and microbes can infect wildlife, it is unlikely to be long before they reach neighboring domestic animals, agricultural environments, and humans (Arnold et al, 2016; Cui et al, 2023; Greig et al, 2015; Ramey & Ahlstrom, 2020). An article published as this manuscript was under review provides empirical evidence that socioecological effects of urbanization can facilitate the transfer of mobile genetic elements between humans, livestock, and wildlife (Hassell et al, 2023) While this research focuses on zoonotic implications more generally, it adds weight to the argument that exploring AMR in nondomestic animals and their environment could be essential to support our understanding of the timeline, drivers, and consequences of resistance.…”

“…Unfortunately, habitat degradation, climate change, pollution, intensive farming, and human encroachment are having a major influence on biodiversity including that of plants and microbes (Peixoto et al, 2022 ; Wang et al, 2018 ). A loss of biodiversity at any level has negative impacts on the functionality, productivity, and resilience of ecosystems (Hassell et al, 2023 ; Sutherland et al, 2023 ; Symstad et al, 1998 ; van der Plas, 2019 ). However, a loss of natural antimicrobial diversity could mean that wildlife has a limited arsenal of antimicrobial compounds in their natural environments, while also impacting pharmacological pipelines.…”

“…In combination, the framing of AMR as a form of human–wildlife conflict and engaging with stakeholders and data in the HWC area will significantly enrich our understanding of AMR by accelerating transdisciplinary action to tackle AMR via a holistic One Health approach. It is becoming impossible to disregard the health implications of interactions between humans, wildlife and domesticated animals and environments (Hassell et al, 2023 ; Otu et al, 2021 ). However, current AMR narratives and global guidance neglect wildlife, and this represents a major gap in our understanding of AMR as a One Health challenge.…”