Assessing Biosecurity Risks for the Introduction and Spread of Diseases Among Commercial Sheep Properties in New South Wales, Australia, Using Foot-and-Mouth Disease as a Case Study

Abstract

Sheep production systems are a major industry in Australia, with a gross value of roughly $4.66 billion; 87.3% of which is attributable to export markets. Exotic diseases such as foot-and-mouth disease (FMD) are a potential threat to the viability of Australia’s export market. Previous outbreaks of FMD in developed countries, and challenges in the management of onshore biosecurity, signify the importance of on-farm biosecurity in controlling disease transmission. This study aims to investigate the risk of disease introduction and spread among New South Wales (NSW) sheep properties using FMD as a case study and draw recommendation for the industry. Exposure and partial consequence assessments, using scenario trees and Monte Carlo stochastic modeling, were conducted to identify pathways of introduction and spread and calculate the probabilities of these pathways occurring. Input parameters were estimated from the data obtained during qualitative interviews with producers and scientific literature. According to the reported practices of sheep producers and assuming each pathway was carrying the FMD virus, the exposure assessment estimates the median (5–95%) probability of FMD exposure of sheep on a naive property to be 0.619 (0.541–0.698), 0.151 (0.085–0.239), 0.235 (0.153–0.324), and 0.710 (0.619–0.791) for introduction through new stock, wildlife, carriers (humans, dogs, and vehicles), and neighbors, respectively. The spread assessment estimated the median probability of FMD spreading from an infected sheep property to neighboring enterprises to be 0.603 (0.504–0.698). A similar probability was estimated for spread via wildlife (0.523; 0.404–0.638); and a lower spread probability was estimated for carriers (0.315; 0.171–0.527), sheep movement (0.285; 0.161–0.462), and dead stock (0.168; 0.070–0.312). The sensitivity analysis revealed that the introduction of an FMD-infected sheep was more influential for exposure via new stock than isolation practices. Sharing adjacent boundaries was found to be the most influential factor for exposure and spread between neighboring enterprises, and to a lesser extent, hygiene practices were found to have the most influence on exposure and spread through carriers. To minimize the potential risk of FMD introduction and spread between sheep properties, maintenance of boundary fences, identification of infected animals before introduction to the property, and hygiene and disinfection practices should be improved.

Development of a quantitative risk assessment of bovine viral diarrhea virus and bovine herpesvirus-1 introduction in dairy cattle herds to improve biosecurity

“…On the other hand, cleaning and disinfection of transport vehicles is compulsory but the efficacy is probably low, and sometimes not applied. Efforts to develop more adequate disinfection points within Spain and more rigorous monitoring would be beneficial in reducing the probability of disease transmission through contaminated vehicles, as demonstrated by previous studies that include international transport (Bronsvoort et al, 2008;Fountain et al, 2018). Furthermore, animal transports in which cattle from different farms were mixed was quite common and increased the probability of disease introduction in several farms.…”

Knowledge and attitudes of Australian livestock producers concerning biosecurity practices

“…Further education of producers on the benefits of onfarm biosecurity and surveillance could promote uptake of practices by increasing self-efficacy of producers. 22 While much of the focus seems to be on the producers, the papers reviewed suggest integrated changes to all levels of the production system and that strengthening of partnerships among stakeholders may be beneficial. Vertical integration of industry into farming operations was shown to result in a higher rate of compliance to biosecurity practices compared to those farms under private ownership.…”

“…and veterinarians may have a role to play here as trusted partners in promoting animal health. Further education of producers on the benefits of on‐farm biosecurity and surveillance could promote uptake of practices by increasing self‐efficacy of producers 22 …”

BOARD INVITED REVIEW: Prospects for improving management of animal disease introductions using disease-dynamic models

“…These approaches are frequently implemented in a spatially explicit context (e.g., Buhnerkempe et al, 2014;Bonney et al, 2018) but do not have to be spatial (e.g., Pepin and VerCauteren, 2016). Nondynamical risk models correlate predictors to case data (in donor or recipient host populations) to make predictions about potential risk in the recipient host population (e.g., Belkhiria et al, 2016) or predict risk probabilistically using conditional probability and historical surveillance patterns (Faverjon et al, 2015;Fountain et al, 2018). Nondynamical risk models have dominated the literature when assessing risks of transboundary introduction by lateral transfer.…”