Abstract
The objective of this paper is to study shedding patterns of cows infected with Mycobacterium avium subsp. paratuberculosis (MAP). While multiple single farm studies of MAP dynamics were reported, there is not large scale meta-analysis of both natural and experimental infections. Large difference in shedding patterns between experimentally and naturally infected cows were observed. Experimental infections are thus probably driven by different pathological mechanisms. For further evaluations of shedding patterns only natural infections were used. Within such infections, the transition to high shedding was studied as a proxy to the development of a clinical disease. The majority of studied cows never developed high shedding levels. Those that do, typically never reduced their shedding level to low or no shedding. Cows that eventually became high shedders showed a pattern of continuous shedding. In contrast, cows with an intermittent shedding pattern had a low probability to ever become high shedders. In addition, cows that start shedding at a younger age (less than three years of age) have a lower hazard of becoming high shedders compared to cows starting to shed at an older age. These data suggest the presence of three categories of immune control. Cows that are intermittent shedders have the infection process under control (no progressive infection). Cows that start shedding persistently at a young age partially control the infection, but eventually will be high shedders (slow progressive infection), while cows that start shedding persistently at an older age cannot effectively control the infection and become high shedders rapidly.
Original language | English |
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Article number | 66 |
Journal | Veterinary Research |
Volume | 46 |
Issue number | 1 |
DOIs | |
State | Published - 19 Jun 2015 |
Bibliographical note
Publisher Copyright:© 2015 Mitchell et al.
Funding
We acknowledge the dairy farmers that contributed to the collection of data from their farms. This work was conducted with partial funding provided at the National Institute for Mathematical and Biological Synthesis, an institute sponsored by the National Science Foundation, the U.S. Department of Homeland Security, and the U.S. Department of Agriculture through NSF Award #EF-0832858, with additional support from The University of Tennessee, Knoxville. We acknowledge the long term funding of the Regional Dairy Quality Management Alliance through a collaborative contract with the USDA agricultural research services.
Funders | Funder number |
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National Science Foundation | |
Directorate for Biological Sciences | 0832858 |
U.S. Department of Homeland Security | |
U.S. Department of Agriculture | |
University of Tennessee |