Epidemics in markets with trade friction and imperfect transactions.
Market trade-routes can support infectious-disease transmission, impacting biological populations and even disrupting trade that conduces the disease. Epidemiological models increasingly account for reductions in infectious contact, such as risk-aversion behaviour in response to pathogen outbreaks. However, responses in market dynamics clearly differ from simple risk aversion, as are driven by other motivation and conditioned by "friction" constraints (a term we borrow from labour economics). Consequently, the propagation of epidemics in markets of, for example livestock, is frictional due to time and cost limitations in the production and exchange of potentially infectious goods. Here we develop a coupled economic-epidemiological model where transient and long-term market dynamics are determined by trade friction and agent adaptation, and can influence disease transmission. The market model is parameterised from datasets on French cattle and pig exchange networks. We show that, when trade is the dominant route of transmission, market friction can be a significantly stronger determinant of epidemics than risk-aversion behaviour. In particular, there is a critical level of friction above which epidemics do not occur, which suggests some epidemics may not be sustained in highly frictional markets. In addition, friction may allow for greater delay in removal of infected agents that still mitigates the epidemic and its impacts. We suggest that policy for minimising contagion in markets could be adjusted to the level of market friction, by adjusting the urgency of intervention or by increasing friction through incentivisation of larger-volume less-frequent transactions that would have limited effect on overall trade flow. Our results are robust to model specificities and can hold in the presence of non-trade disease-transmission routes.
INRA, UR 1404 Mathématiques et Informatique Appliquées du Génome à l'Environnement, F-78350 Jouy-en-Josas, France; Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, United Kingdom; AgroParisTech, F-75005 Paris, France. Electronic address: mathieu@moslonkalefebvre.com.
Mathieu
M
Moslonka-Lefebvre
INRA, UR 1404 Mathématiques et Informatique Appliquées du Génome à l'Environnement, F-78350 Jouy-en-Josas, France.
Hervé
H
Monod
Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, United Kingdom.
Christopher A
CA
Gilligan
INRA, UR 1404 Mathématiques et Informatique Appliquées du Génome à l'Environnement, F-78350 Jouy-en-Josas, France.
Elisabeta
E
Vergu
Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, United Kingdom.
João A N
JA
Filipe
D000818:Animals; D002417:Cattle; D003132:Commerce; D003141:Communicable Diseases / Q000453:epidemiology*; D058872:Epidemics; D005602:France; D006801:Humans; D058751:Livestock; D008954:Models, Biological; D018803:Models, Economic; D011336:Probability; D013552:Swine; D013997:Time Factors
Behavioural response; Economic epidemiology; Epidemic threshold; Trade networks