Transmission Interaction Persistence (TIP): A Supply Chain and Epidemiologic Model for Zoonotic Viruses Outbreaks

Abstract

Problem definition: Zoonotic viruses that jump from animals to humans, such as avian influenza or SARS have been the cause of major global pandemics in the last several decades. China has been the source of many of these pandemics. Interestingly, many outbreaks in China have been linked live animal markets, even in situations where the surrounding farms supplying markets had very low infection rates. This suggests that these markets potentially amplify and propagate the spread of zoonotic viruses. Yet, traditional epidemiologic models cannot explain the observed outbreaks in these markets.

Methodology/results: This paper develops an innovative epidemiologic model that incorporates supply chain and in-market operational dynamics and captures mechanisms which could explain the empirical evidence regarding the role of these markets in driving the spread of zoonotic viruses, and specifically avian influenza. By integrating stochastic supply chain and in-market dynamics into a traditional epidemiologic model, the paper describes a new model called Transmission, Interaction, and Persistence (TIP). The analytical results demonstrate how major outbreaks could occur in markets, even when the infection rates among animals sourced from the surrounding farms are very low, and the animals stay in the market less than one day. This is the result of two important dynamics. The first concerns with the supply chain structure in which markets serve as a consolidation point of agricultural inputs from many small farms. The other is driven by in-market operations that affect environmental in-market infection evolution, particularly, persistent infection through two-sided interactions between animals and wastewater, surfaces and feed.

Managerial implications: This paper highlights the important role of supply chain structure and market operational dynamics and the corresponding impact they have on environmental infections, in driving the spread of zoonotic viruses. Additionally, the TIP model enables to evaluate the effectiveness of critical in-market and supply chain interventions to prevent infection outbreaks.

Keywords: Global Health, Zoonotic Diseases, Epidemiology, Supply Chain, Food Safety