Survival analysis of clinical mastitis data using a nested frailty Cox model fit as a mixed-effects Poisson model

Elghafghuf, Adel; Dufour, Simon; Reyher, Kristen K; Dohoo, Ian R.; Stryhn, Henrik

doi:10.1016/j.prevetmed.2014.09.013

Cited by 26 publications

(23 citation statements)

References 50 publications

(1 reference statement)

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“…In short, in this cohort the cows from 91 farms were followed in 2007 and 2008, and all CM events as well as severity of these events were recorded on a 1 to 3 scale as described by Sears et al ( 17 ). In this study, a severity score of 3 (i.e., severe CM) was observed in 20% of CM cases when using the 74 herds validated for CM reporting ( 28 ). We therefore assumed that 20% of the CM cases reported by dairy producers would be severe cases and treated with both local and systemic treatments.…”

Section: Methodsmentioning

confidence: 70%

“…In the study by Olde Riekerink et al ( 30 ), mean incidence rate of CM was estimated at 23 cases per 100 cows-year during 2003 to 2005. In the National Cohort of Dairy Farms (NCDF) study, conducted in 2007 and 2008 a median incidence rate of 21.3 case per cow-305 days was reported ( 28 ). At first sight CM incidence rate may seem to be decreasing over time, but in Elghagguf et al ( 28 ) only first cases were included, whereas in Olde Riekerink et al ( 30 ) and the current study, both first and repeated cases were included.…”

Section: Discussionmentioning

confidence: 99%

“…In the National Cohort of Dairy Farms (NCDF) study, conducted in 2007 and 2008 a median incidence rate of 21.3 case per cow-305 days was reported ( 28 ). At first sight CM incidence rate may seem to be decreasing over time, but in Elghagguf et al ( 28 ) only first cases were included, whereas in Olde Riekerink et al ( 30 ) and the current study, both first and repeated cases were included. In addition, Elghafghuf et al ( 28 ) study was prospective with frequent follow-ups and more precise measurements, while in the current study, number of CM cases within 12 months reported by producers were used to estimate the overall CM incidence, which may possibly result in a certain underestimation.…”

Section: Discussionmentioning

confidence: 99%

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Herd-Level Mastitis-Associated Costs on Canadian Dairy Farms

Aghamohammadi

Haine

Kelton³

et al. 2018

Front. Vet. Sci.

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160

121

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Mastitis imposes considerable and recurring economic losses on the dairy industry worldwide. The main objective of this study was to estimate herd-level costs incurred by expenditures and production losses associated with mastitis on Canadian dairy farms in 2015, based on producer reports. Previously, published mastitis economic frameworks were used to develop an economic model with the most important cost components. Components investigated were divided between clinical mastitis (CM), subclinical mastitis (SCM), and other costs components (i.e., preventive measures and product quality). A questionnaire was mailed to 374 dairy producers randomly selected from the (Canadian National Dairy Study 2015) to collect data on these costs components, and 145 dairy producers returned a completed questionnaire. For each herd, costs due to the different mastitis-related components were computed by applying the values reported by the dairy producer to the developed economic model. Then, for each herd, a proportion of the costs attributable to a specific component was computed by dividing absolute costs for this component by total herd mastitis-related costs. Median self-reported CM incidence was 19 cases/100 cow-year and mean self-reported bulk milk somatic cell count was 184,000 cells/mL. Most producers reported using post-milking teat disinfection (97%) and dry cow therapy (93%), and a substantial proportion of producers reported using pre-milking teat disinfection (79%) and wearing gloves during milking (77%). Mastitis costs were substantial (662 CAD per milking cow per year for a typical Canadian dairy farm), with a large portion of the costs (48%) being attributed to SCM, and 34 and 15% due to CM and implementation of preventive measures, respectively. For SCM, the two most important cost components were the subsequent milk yield reduction and culling (72 and 25% of SCM costs, respectively). For CM, first, second, and third most important cost components were culling (48% of CM costs), milk yield reduction following the CM events (34%), and discarded milk (11%), respectively. This study is the first since 1990 to investigate costs of mastitis in Canada. The model developed in the current study can be used to compute mastitis costs at the herd and national level in Canada.

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Section: Methodsmentioning

confidence: 70%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Herd-Level Mastitis-Associated Costs on Canadian Dairy Farms

Aghamohammadi

Haine

Kelton³

et al. 2018

Front. Vet. Sci.

Self Cite

160

121

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“…The outcome of any IMI is dependent on several host factors including nutritional status, immune status, genetic makeup, parity, and stage of lactation (Rupp and Boichard, 2003;Hertl et al, 2011;Elghafghuf et al, 2014). Despite the extensive influence of the host on the progression and outcome of IMI, pathogenspecific factors also play an important role in the pathophysiology of infection.…”

Section: Pathogen-associated Host Immune Responsementioning

confidence: 99%

“…The prevalence of IMI in a herd is dependent on the rate at which new infections arise and the length of those infections (Wilson et al, 1997). These in turn are influenced by a variety of factors such as parity, stage of lactation, the nature of the infectious agent, and the nutrition and environment of the cow (Smith et al, 1984;Hertl et al, 2011;Elghafghuf et al, 2014;Moyes, 2015). Although contagious pathogens are transmitted from cow to cow, usually at milking, environmental pathogens, with a reservoir in the cow's environment, often infect opportunistically.…”

Section: Introductionmentioning

confidence: 99%

Symposium review: Intramammary infections—Major pathogens and strain-associated complexity

Keane

2019

Journal of Dairy Science

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Intramammary infection (IMI) is one of the most costly diseases to the dairy industry. It is primarily due to bacterial infection and the major intramammary pathogens include Escherichia coli, Streptococcus uberis, and Staphylococcus aureus. The severity and outcome of IMI is dependent on several host factors including innate host resistance, energy balance, immune status, parity, and stage of lactation. Additionally, the infecting organism can influence the host immune response and progression of disease. It is increasingly recognized that not only the infecting pathogen species, but also the strain, can affect the transmission, severity, and outcome of IMI. For each of 3 major IMI-associated pathogens, S. aureus, Strep. uberis, and E. coli, specific strains have been identified that are adapted to the intramammary environment. Strain-dependent variation in the host immune response to infection has also been reported. The diversity of strains associated with IMI must be considered if vaccines effective against the full repertoire of mammary pathogenic strains are to be developed. Although important advances have been made recently in understanding the molecular mechanism underpinning strain-specific virulence, further research is required to fully elucidate the cellular and molecular pathogenesis of mammary adapted strains and the role of the strain in influencing the pathophysiology of infection. Improved understanding of molecular pathogenesis of strains associated with bovine IMI will contribute to the development of new control strategies, therapies, and vaccines. The development of enabling technologies such as pathogenomics, transcriptomics, and proteomics can facilitate system-level studies of strain-specific molecular pathogenesis and the identification of key mediators of host-pathogen interactions.

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Diseases of the Mammary Gland

2017

Veterinary Medicine

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Survival analysis of clinical mastitis data using a nested frailty Cox model fit as a mixed-effects Poisson model

Cited by 26 publications

References 50 publications

Herd-Level Mastitis-Associated Costs on Canadian Dairy Farms

Herd-Level Mastitis-Associated Costs on Canadian Dairy Farms

Symposium review: Intramammary infections—Major pathogens and strain-associated complexity

Diseases of the Mammary Gland

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