TY - JOUR
T1 - The spread of bovine tuberculosis in Canadian shared pastures
T2 - Data, model, and simulations
AU - Rossi, Gianluigi
AU - Aubry, Pascale
AU - Dubé, Caroline
AU - Smith, Rebecca L.
N1 - Funding Information:
We want to thank the Canadian Food Inspection Agency for supporting this study through CFIA Canada contract 10000382632.
Publisher Copyright:
© 2018 Her Majesty the Queen in Right of Canada Transboundary and Emerging Diseases © 2018 Blackwell Verlag GmbH
PY - 2019/1
Y1 - 2019/1
N2 - Bovine tuberculosis (bTB), caused by Mycobacterium bovis, is a chronic disease typical of cattle. Nonetheless, it can affect many mammals including humans, making it one of the most widespread zoonotic diseases worldwide. In industrialized countries, the main pathways of introduction of bTB into a herd are animal trade and contact with infected wildlife. In addition, for slow-spreading diseases with a long latent period such as bTB, shared seasonal pastures might be a between-herd transmission pathway, indeed farmers might unknowingly send infected animals to the pasture, since clinical signs are rarely evident in early infection. In this study, we developed a dynamic stochastic model to represent the spread of bTB in pastures. This was tailored to Canadian cow-calf herds, as we calibrated the model with data sourced from a recent bTB outbreak in Western Canada. We built a model for a herd with seasonal management, characterized by its partition into a group staying in the main facility and the remaining group(s) moving to summer pastures. We used this model to estimate the time of the first introduction of bTB into the herd. Furthermore, we expanded the model to include herds categorized as high-risk contacts with the index herd, in order to estimate the potential for disease spread on shared pastures. Finally, we explored two control scenarios to be applied to high-risk farms after the outbreak detection. Our results showed that the first introduction likely happened 3 to 5 years prior to the detection of the index herd, and the probability of bTB spreading in pastures was low, but not negligible. Nevertheless, the surveillance system currently in place was effective to detect potential outbreaks.
AB - Bovine tuberculosis (bTB), caused by Mycobacterium bovis, is a chronic disease typical of cattle. Nonetheless, it can affect many mammals including humans, making it one of the most widespread zoonotic diseases worldwide. In industrialized countries, the main pathways of introduction of bTB into a herd are animal trade and contact with infected wildlife. In addition, for slow-spreading diseases with a long latent period such as bTB, shared seasonal pastures might be a between-herd transmission pathway, indeed farmers might unknowingly send infected animals to the pasture, since clinical signs are rarely evident in early infection. In this study, we developed a dynamic stochastic model to represent the spread of bTB in pastures. This was tailored to Canadian cow-calf herds, as we calibrated the model with data sourced from a recent bTB outbreak in Western Canada. We built a model for a herd with seasonal management, characterized by its partition into a group staying in the main facility and the remaining group(s) moving to summer pastures. We used this model to estimate the time of the first introduction of bTB into the herd. Furthermore, we expanded the model to include herds categorized as high-risk contacts with the index herd, in order to estimate the potential for disease spread on shared pastures. Finally, we explored two control scenarios to be applied to high-risk farms after the outbreak detection. Our results showed that the first introduction likely happened 3 to 5 years prior to the detection of the index herd, and the probability of bTB spreading in pastures was low, but not negligible. Nevertheless, the surveillance system currently in place was effective to detect potential outbreaks.
KW - beef herd
KW - bovine tuberculosis
KW - parameter estimation
KW - pasture land
KW - simulations
UR - http://www.scopus.com/inward/record.url?scp=85057822014&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85057822014&partnerID=8YFLogxK
U2 - 10.1111/tbed.13066
DO - 10.1111/tbed.13066
M3 - Article
C2 - 30407739
AN - SCOPUS:85057822014
VL - 66
SP - 562
EP - 577
JO - Transboundary and Emerging Diseases
JF - Transboundary and Emerging Diseases
SN - 1865-1674
IS - 1
ER -