Within-herd transmission of Mycoplasma bovis infections after initial detection in dairy cows.

Autor:	Biesheuvel MM; Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N4N1. Electronic address: marit.biesheuvel@ucalgary.ca., Ward C; Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, MN 55455., Penterman P; Royal GD, Deventer, the Netherlands 7418 EZ., van Engelen E; Royal GD, Deventer, the Netherlands 7418 EZ., van Schaik G; Royal GD, Deventer, the Netherlands 7418 EZ; Faculty of Veterinary Medicine, Department of Population Health Sciences, Utrecht University, Utrecht, the Netherlands 3584 CL., Deardon R; Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N4N1; Faculty of Science, Department of Mathematics and Statistics, University of Calgary, Calgary, AB, Canada T2N 1N4., Barkema HW; Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada T2N4N1.
Jazyk:	angličtina
Zdroj:	Journal of dairy science [J Dairy Sci] 2024 Jan; Vol. 107 (1), pp. 516-529. Date of Electronic Publication: 2023 Sep 13.
DOI:	10.3168/jds.2023-23407
Abstrakt:	Mycoplasma bovis outbreaks in cattle, including pathogen spread between age groups, are not well understood. Our objective was to estimate within-herd transmission across adult dairy cows, youngstock, and calves. Results from 3 tests (PCR, ELISA, and culture) per cow and 2 tests (PCR and ELISA) per youngstock and calf were used in an age-stratified susceptible-infected-removed/recovered (SIR) model to estimate within-herd transmission parameters, pathways, and potential effects of farm management practices. A cohort of adult cows, youngstock, and calves on 20 Dutch dairy farms with a clinical outbreak of M. bovis in adult cows were sampled, with collection of blood, conjunctival fluid, and milk from cows, and blood and conjunctival fluid from calves and youngstock, 5 times over a time span of 12 wk. Any individual with at least one positive laboratory test was considered M. bovis-positive. Transmission dynamics were modeled using an age-stratified SIR model featuring 3 age strata. Associations with farm management practices were explored using Fisher's exact tests and Poisson regression. Estimated transmission parameters were highly variable among herds and cattle age groups. Notably, transmission from cows to cows, youngstock, or to calves was associated with R-values ranging from 1.0 to 80 secondarily infected cows per herd, 1.2 to 38 secondarily infected youngstock per herd, and 0.1 to 91 secondarily infected calves per herd, respectively. In case of transmission from youngstock to youngstock, calves or to cows, R-values were 0.7 to 96 secondarily infected youngstock per herd, 1.1 to 76 secondarily infected calves per herd, and 0.1 to 107 secondarily infected cows per herd. For transmission from calves to calves, youngstock or to cows, R-values were 0.5 to 60 secondarily infected calves per herd, 1.1 to 41 secondarily infected youngstock per herd, and 0.1 to 47 secondarily infected cows per herd. Among on-farm transmission pathways, cow-to-youngstock, cow-to-calf, and cow-to-cow were identified as most significant contributors, with calf-to-calf and calf-to-youngstock also having noteworthy roles. Youngstock-to-youngstock was also implicated, albeit to a lesser extent. Whereas the primary focus was a clinical outbreak of M. bovis among adult dairy cows, it was evident that transmission extended to calves and youngstock, contributing to overall spread. Factors influencing transmission and specific transmission pathways were associated with internal biosecurity (separate caretakers for various age groups, number of people involved), external biosecurity (contractors, external employees), as well as indirect transmission routes (number of feed and water stations). (© 2024, The Authors. Published by Elsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association®. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).)
Databáze:	MEDLINE
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