Pathways to zoonotic spillover

Abstract

Zoonotic spillover, which is the transmission of a pathogen from a vertebrate animal to a human, presents a global public health burden but is a poorly understood phenomenon. Zoonotic spillover requires several factors to align, including the ecological, epidemiological and behavioural determinants of pathogen exposure, and the within-human factors that affect susceptibility to infection. In this Opinion article, we propose a synthetic framework for animal-to-human transmission that integrates the relevant mechanisms. This framework reveals that all zoonotic pathogens must overcome a hierarchical series of barriers to cause spillover infections in humans. Understanding how these barriers are functionally and quantitatively linked, and how they interact in space and time, will substantially improve our ability to predict or prevent spillover events. This work provides a foundation for transdisciplinary investigation of spillover and synthetic theory on zoonotic transmission.

Ecological spillover dynamics of organisms from urban to natural landscapes

“…This is especially true for the cases we present of pathogens moving between the urban matrix and wildlands. The detailed synthesis presented by Plowright et al (2017) is exactly the kind of analysis required for the (non-pathogen) factors we propose in our framework. Thus, the framework as proposed by Plowright et al (2017) is nested within the larger framework of ecological spillover, especially as relates to the factors identified that precede human exposure to pathogens.…”

“…Recently, Plowright et al (2017), proposed a detailed synthetic framework for assessing zoonotic spillover potential (animal-to-human transmission). This framework incorporates the rich research history in epidemiology and disease ecology into an interacting hierarchy of spillover pathways and bottlenecks to understand gaps in knowledge, determine the parameters of risk analysis, examine potential points of intervention and control, and develop mathematical models for zoonotic spillover, Ecological spillover dynamics of organisms from urban to natural landscapes | 7 among other goals.…”

“…animal-to-human spillover (Sauvage, Langlais and Pontier 2007;Lloyd-Smith et al 2009;Plowright et al 2014Plowright et al , 2017, animal-to-animal (Dobson 2004;Childs, Richt and Mackenzie 2007) and plant-to-plant (Beckstead et al 2010), see Daszak, Cunningham and Hyatt (2000) for general definition] and in invasive species literature (Meeus et al 2011;Dunn and Hatcher 2015), but expands the concept to include all potential ecological interactions that result in ecological effects moving from urban to wildland environments.…”

Quantifying direct and indirect contacts for the potential transmission of infection between species using a multilayer contact network

“…Between-species transmission of infection in multi-host disease systems remains poorly understood, despite representing a potentially important opportunity for disease control (Plowright et al, 2017;Webster et al, 2017). The behaviours that might result in transmission of infections between species are often rare (Viana et al, 2014), with successful transfer and establishment of the pathogen in a new host being rarer still (Woolhouse et al, 2001).…”

“…This distinction can be particularly important when direct interactions among potential hosts are rare, which is likely to be the case for between-species transmission (Viana et al, 2014). Identifying the relative importance of direct and indirect transmission, and the behaviours involved, are therefore likely to be important prerequisites to the development of effective disease management strategies (Plowright et al, 2017;Webster et al, 2017).…”