Matrix matters: a new approach for understanding zoonoses emergence in agricultural landscapes

Background/Question/Methods

Land use change, along with changes in agriculture, are major drivers of zoonotic spillovers from wildlife to humans. The emerging narrative is that deforestation, fragmentation, and general conversion of forest to agriculture is accelerating zoonotic spillover by reducing biodiversity, allowing host reservoir populations to increase, and increasing human contact with wildlife. However, this narrative ignores that the quality of the agricultural matrix (i.e., how much the agricultural system resembles the natural/undisturbed system) varies with different kinds of agriculture, and how political economy influences both the quality of the matrix and the social relationships that drive disease transmission and determines whether a spillover event is merely spread locally and dies off, or has the potential to become a global pandemic. Pathogens have complex responses to environmental change across spatial and temporal scales. Such complexity does not negate the need to develop a general framework to understand the relationship between land use and zoonoses. But it does suggest that such analysis must be nuanced and incorporate the variety of agricultural matrices within which pathogens emerge, and through which they need to move, in order to reach centers of critical human population densities where rapid spread becomes possible.

Results/Conclusions

Here we present a novel approach to the land use-zoonoses relationship that, 1) focuses on the quality of the agricultural matrix and its potential to play a role in the emergence and transmission of zoonotic pathogens, and 2) places pathogen spillover and spread within a socio-economic and political context. Using examples of different kinds of agricultural matrices, we discuss the probability of emergence and transmission of pathogens and present a theoretical framework that allows for the incorporation of these factors in an analysis of zoonoses. This novel approach recognizes the complexities involved in the zoonoses-landscape interaction and distinguishes between different kinds of agricultural matrices and their impacts on emergence and transmission based on ecological and sociopolitical factors.