The infectious disease trap of animal agriculture

Abstract

Infectious diseases originating from animals (zoonotic diseases) have emerged following deforestation from agriculture. Agriculture can reduce its land use through intensification, i.e., improving resource use efficiency. However, intensive management often confines animals and their wastes, which also fosters disease emergence. Therefore, rising demand for animal-sourced foods creates a "trap" of zoonotic disease risks: extensive land use on one hand or intensive animal management on the other. Not all intensification poses disease risks; some methods avoid confinement and improve animal health. However, these "win-win" improvements alone cannot satisfy rising meat demand, particularly for chicken and pork. Intensive poultry and pig production entails greater antibiotic use, confinement, and animal populations than beef production. Shifting from beef to chicken consumption mitigates climate emissions, but this common strategy neglects zoonotic disease risks. Preventing zoonotic diseases requires international coordination to reduce the high demand for animal-sourced foods, improve forest conservation governance, and selectively intensify the lowest-producing ruminant animal systems without confinement.

Fig. 1.. Higher incomes are associated with high meat demand that must be met through intensification or deforestation (or both).

Intensification can trigger higher meat demand through lower prices, because meat demand is elastic with respect to its cost. Intensification and deforestation are highlighted in orange, as both have caused recent zoonotic disease emergence and are predicted to continue doing so. Intensification is colored by a gradient to indicate that intensification strategies lie on a gradient of helpful/neutral to harmful with respect to zoonosis risks.

Fig. 2.. A three-pillar approach for preventing zoonotic disease emergence and reducing environmental impacts from animal agriculture (center).

Within individual circles and the intersections between the two, limitations of adopting only one or two strategies are described.

Fig. 3.. Requirements to produce 1 metric ton of meat (dressed carcass weight), averaged among all OECD countries and weighted by production quantity, base year 2010.

(A) Hectares required for the production of animal feed (crops, pastures, and forages) in natively forested areas, calculated by the author from geospatial potential vegetation data and agricultural production data in (9) and sources therein. (B) Grams of antibiotics used, derived from (74). (C) Number of animals required for slaughter, from United Nations FAOSTAT (105). OECD, Organization for Economic Co-operation and Development.