Blowback: new formal perspectives on agriculturally driven pathogen evolution and spread

On Disease Configurations, Black-Grass Blowback, and Probiotic Pest Management

This article explores approaches to managing pests that are being developed in response to the faltering effectiveness of antibiotic regimes of chemical control. It focuses on black-grass (Alopecurus myosuroides), an endemic plant in European agriculture that has emerged as a serious yield-robber with increasing levels of herbicidal resistance. Following farmers and agronomists who have developed "integrated" approaches to black-grass management, the article identifies approaches to biosecurity that do not target unwanted life so much as they modulate ecological systems in their entirety. Pathogenesis, in this relational understanding, follows not from breaches of dangerous life into healthy space, but from ecological intra-actions that enable the proliferation of some life to compromise the multispecies livability of the body in question. The article contributes to the literature by detailing how this configurational approach works in the world. It traces the polymorphic spatial imaginaries required to map pests well; the process of knowledge intensification needed to reveal which configurations can resist pathogenesis; and the probiotic biopolitical interventions used to safeguard farmland productivity. The article uses black-grass to present a temporal metanarrative of intensive farming causing ecological blowback, leading to the development of approaches to pest management predicated on a pragmatic tolerance toward unwanted life.

Genotype and sex-based host variation in behaviour and susceptibility drives population disease dynamics

Host heterogeneity in pathogen transmission is widespread and presents a major hurdle to predicting and minimizing disease outbreaks. Using Drosophila melanogaster infected with Drosophila C virus as a model system, we integrated experimental measurements of social aggregation, virus shedding, and disease-induced mortality from different genetic lines and sexes into a disease modelling framework. The experimentally measured host heterogeneity produced substantial differences in simulated disease outbreaks, providing evidence for genetic and sex-specific effects on disease dynamics at a population level. While this was true for homogeneous populations of single sex/genetic line, the genetic background or sex of the index case did not alter outbreak dynamics in simulated, heterogeneous populations. Finally, to explore the relative effects of social aggregation, viral shedding and mortality, we compared simulations where we allowed these traits to vary, as measured experimentally, to simulations where we constrained variation in these traits to the population mean. In this context, variation in infectiousness, followed by social aggregation, was the most influential component of transmission. Overall, we show that host heterogeneity in three host traits dramatically affects population-level transmission, but the relative impact of this variation depends on both the susceptible population diversity and the distribution of population-level variation.

One Health and Zoonotic Uncertainty in Singapore and Australia: Examining Different Regimes of Precaution in Outbreak Decision-Making

A One Health approach holds great promise for attenuating the risk and burdens of emerging infectious diseases (EIDs) in both human and animal populations. Because the course and costs of EID outbreaks are difficult to predict, One Health policies must deal with scientific uncertainty, whilst addressing the political, economic and ethical dimensions of communication and intervention strategies. Drawing on the outcomes of parallel Delphi surveys conducted with policymakers in Singapore and Australia, we explore the normative dimensions of two different precautionary approaches to EID decision-making—which we call regimes of risk management and organizing uncertainty, respectively. The imperative to act cautiously can be seen as either an epistemic rule or as a decision rule, which has implications for how EID uncertainty is managed. The normative features of each regime, and their implications for One Health approaches to infectious disease risks and outbreaks, are described. As One Health attempts to move upstream to prevent rather than react to emergence of EIDs in humans, we show how the approaches to uncertainty, taken by experts and decision-makers, and their choices about the content and quality of evidence, have implications for who pays the price of precaution, and, thereby, social and global justice.

Hookworms Make Us Human: The Microbiome, Eco-immunology, and a Probiotic Turn in Western Health Care

Historians of science have identified an ecological turn underway in immunology, driven by the mapping of the human microbiome and wider environmentalist anxieties. A figure is emerging of the human as a holobiont, composed of microbes and threatened by both microbial excess and microbial absence. Antimicrobial approaches to germ warfare are being supplemented by probiotic approaches to restoring microbial life. This article examines the political ecology of this probiotic turn in Western health care. It focuses on Necator americanus-a species of human hookworm-and its relations with immunologists. The analysis moves from a history of human disentanglement from hookworm, to contemporary anxieties about their absence. It examines the reintroduction of worms for helminthic therapy and explores emerging trajectories for probiotic health care involving the synthesis, modification, and/or restoration of worms and their salutary ecologies. The conclusion differentiates these trajectories and identifies an emerging model of "post-paleo" microbiopolitics.

Did Neoliberalizing West African Forests Produce a New Niche for Ebola?

A recent study introduced a vaccine that controls Ebola Makona, the Zaire ebolavirus variant that has infected 28,000 people in West Africa. We propose that even such successful advances are insufficient for many emergent diseases. We review work hypothesizing that Makona, phenotypically similar to much smaller outbreaks, emerged out of shifts in land use brought about by neoliberal economics. The epidemiological consequences demand a new science that explicitly addresses the foundational processes underlying multispecies health, including the deep-time histories, cultural infrastructure, and global economic geographies driving disease emergence. The approach, for instance, reverses the standard public health practice of segregating emergency responses and the structural context from which outbreaks originate. In Ebola's case, regional neoliberalism may affix the stochastic "friction" of ecological relationships imposed by the forest across populations, which, when above a threshold, keeps the virus from lining up transmission above replacement. Export-led logging, mining, and intensive agriculture may depress such functional noise, permitting novel spillovers larger forces of infection. Mature outbreaks, meanwhile, can continue to circulate even in the face of efficient vaccines. More research on these integral explanations is required, but the narrow albeit welcome success of the vaccine may be used to limit support of such a program.

The dawn of Structural One Health: a new science tracking disease emergence along circuits of capital

The One Health approach integrates health investigations across the tree of life, including, but not limited to, wildlife, livestock, crops, and humans. It redresses an epistemological alienation at the heart of much modern population health, which has long segregated studies by species. Up to this point, however, One Health research has also omitted addressing fundamental structural causes underlying collapsing health ecologies. In this critical review we unpack the relationship between One Health science and its political economy, particularly the conceptual and methodological trajectories by which it fails to incorporate social determinants of epizootic spillover. We also introduce a Structural One Health that addresses the research gap. The new science, open to incorporating developments across the social sciences, addresses foundational processes underlying multispecies health, including the place-specific deep-time histories, cultural infrastructure, and economic geographies driving disease emergence. We introduce an ongoing project on avian influenza to illustrate Structural One Health's scope and ambition. For the first time researchers are quantifying the relationships among transnational circuits of capital, associated shifts in agroecological landscapes, and the genetic evolution and spatial spread of a xenospecific pathogen.