Modeling of Mycobacterium avium subsp. paratuberculosis dynamics in a dairy herd: An individual based approach

Al-Mamun, Mohammad A.; Smith, Rebecca L.; Schukken, Y.H.; Gröhn, Yrjö T.

doi:10.1016/j.jtbi.2016.08.014

Cited by 16 publications

(28 citation statements)

References 43 publications

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“…Simulation models are useful to explore the potential of different strategies within a farm [14], [15]. This is especially true regarding paratuberculosis because it is slowly developing and lack of perfect tests.…”

Section: Introductionmentioning

confidence: 99%

Adaptive Test Schemes for Control of Paratuberculosis in Dairy Cows

et al. 2016

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Paratuberculosis is a chronic infection that in dairy cattle causes reduced milk yield, weight loss, and ultimately fatal diarrhea. Subclinical animals can excrete bacteria (Mycobacterium avium ssp. paratuberculosis, MAP) in feces and infect other animals. Farmers identify the infectious animals through a variety of test-strategies, but are challenged by the lack of perfect tests. Frequent testing increases the sensitivity but the costs of testing are a cause of concern for farmers. Here, we used a herd simulation model using milk ELISA tests to evaluate the epidemiological and economic consequences of continuously adapting the sampling interval in response to the estimated true prevalence in the herd. The key results were that the true prevalence was greatly affected by the hygiene level and to some extent by the test-frequency. Furthermore, the choice of prevalence that will be tolerated in a control scenario had a major impact on the true prevalence in the normal hygiene setting, but less so when the hygiene was poor. The net revenue is not greatly affected by the test-strategy, because of the general variation in net revenues between farms. An exception to this is the low hygiene herd, where frequent testing results in lower revenue. When we look at the probability of eradication, then it is correlated with the testing frequency and the target prevalence during the control phase. The probability of eradication is low in the low hygiene herd, and a test-and-cull strategy should probably not be the primary strategy in this herd. Based on this study we suggest that, in order to control MAP, the standard Danish dairy farm should use an adaptive strategy where a short sampling interval of three months is used when the estimated true prevalence is above 1%, and otherwise use a long sampling interval of one year.

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Section: Introductionmentioning

confidence: 99%

Adaptive Test Schemes for Control of Paratuberculosis in Dairy Cows

et al. 2016

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“…Several models have been published that represent Map spread within a dairy cattle herd (reviewed in [ 30 ], and more recently [ 29 , 31 – 38 ]). We selected a stochastic compartmental model that offers an up-to-date description of Map spread within a dairy cattle herd.…”

Section: Methodsmentioning

confidence: 99%

Which phenotypic traits of resistance should be improved in cattle to control paratuberculosis dynamics in a dairy herd: a modelling approach

Romdhane

Beaunée

Camanes

et al. 2017

Vet Res

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Paratuberculosis is a worldwide disease causing production losses in dairy cattle herds. Variability of cattle response to exposure to Mycobacterium avium subsp. paratuberculosis (Map) has been highlighted. Such individual variability could influence Map spread at larger scale. Cattle resistance to paratuberculosis has been shown to be heritable, suggesting genetic selection could enhance disease control. Our objective was to identify which phenotypic traits characterising the individual course of infection influence Map spread in a dairy cattle herd. We used a stochastic mechanistic model. Resistance consisted in the ability to prevent infection and the ability to cope with infection. We assessed the effect of varying (alone and combined) fourteen phenotypic traits characterising the infection course. We calculated four model outputs 25 years after Map introduction in a naïve herd: cumulative incidence, infection persistence, and prevalence of infected and affected animals. A cluster analysis identified influential phenotypes of cattle resistance. An ANOVA quantified the contribution of traits to model output variance. Four phenotypic traits strongly influenced Map spread: the decay in susceptibility with age (the most effective), the quantity of Map shed in faeces by high shedders, the incubation period duration, and the required infectious dose. Interactions contributed up to 12% of output variance, highlighting the expected added-value of improving several traits simultaneously. Combinations of the four most influential traits decreased incidence to less than one newly infected animal per year in most scenarios. Future genetic selection should aim at improving simultaneously the most influential traits to reduce Map spread in cattle populations.Electronic supplementary materialThe online version of this article (doi:10.1186/s13567-017-0468-8) contains supplementary material, which is available to authorized users.

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“…Several modeling studies have shown recently that control programmes that are aimed at eliminating high shedders of paratuberculosis are biologically and economically effective, whereas complete elimination of paratuberculosis from endemically infected herds and areas has repeatedly shown to be not a cost efficient approach (Kirkeby et al 2016, Al-Mamun et al 2016. In any case, the required control programme aimed at eliminating high shedders certainly means that the number of shedders on farms in the Netherlands will be among the lowest in the world.…”

Section: Problems In Farm Animal Healthmentioning

confidence: 99%