Ebola in the Hog Sector: Modeling Pandemic Emergence in Commodity Livestock

Commodity agriculture represents an expanding sink for a growing array of zoonotic pathogens. The emergence of novel strains of Ebola by way of economically driven shifts in husbandry and horticulture appears one such transition. Following up experimental studies of Ebola transmission, the agroeconomic origins of the Zaire ebolavirus outbreak in West Africa, and reports of endemic Reston ebolavirus in commercial hog in the Philippines and China, we develop a series of stochastic models that explicitly integrate epidemiology, spatial dynamics, and economics. Our inductive modeling suggests repeated punctuated emergence and human spillover of foodborne pathogens are intrinsic to industrial systems of production. In contrast to traditional and conservation agroecologies, by its accelerated and geographically expansive production of genetically uniform seed and stock, highly capitalized agriculture appears especially vulnerable to sudden shifts in disease evolution and spread. Industrial food production strips out environmental stochasticity that can cap pathogen population growth. The mechanisms for such explosive epidemiologies appear fundamentally founded in economic policy and practice. A variant of the Black–Scholes pricing model implies that pathogen propagation in intensive agrifood production outpaces the margins the sector allocates to biocontrol and containment across large expanses of the model’s parameter space. The resulting financial gaps appear met by externalizing the epidemiological costs of industrial food production to livestock morbidity, contract producers, farmworker and consumer health, smallholder markets, local wildlife, off-site environments, and government budgets across administrative units. By way of the models’ results, we hypothesize that as the hog sector expands for export, including across areas of Africa in which Ebola has already emerged as a human infection, multiple Ebola strains will follow Reston’s trajectory, evolving novel phenotypes in livestock and repeatedly spilling over into human populations.