A new compartmental model of Mycobacterium avium subsp. paratuberculosis infection dynamics in cattle

Smith, Rebecca L.; Schukken, Y.H.; Gröhn, Yrjö T.

doi:10.1016/j.prevetmed.2015.10.008

Cited by 23 publications

(27 citation statements)

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“…The infection and testing model (Figure 1) has been previously described [35], and used for an economic analysis of MAP [31]. This is a continuous-time model, simulated over 5 years after a burn-in of 50 years using values representative of US dairy herds.…”

Section: Methodsmentioning

confidence: 99%

Mastitis risk effect on the economic consequences of paratuberculosis control in dairy cattle: A stochastic modeling study

Chiu

Tauer

Grohn³

et al. 2019

Preprint

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18The benefits and efficacy of control programs for herds infected with Mycobacterium avium 19 subsp. paratuberculosis (MAP) have been investigated under various contexts. However, most 20 previous research investigated paratuberculosis control programs in isolation, without modeling 21 the potential association with other dairy diseases. This paper evaluated the benefits of MAP 22 control programs when the herd is also affected by mastitis, a common disease causing the 23 largest losses in dairy production. The effect of typically suggested MAP controls were estimated 24 under the assumption that MAP infection increased the rate of clinical mastitis. We evaluated 25 one hundred twenty three control strategies comprising various combinations of testing, culling, 26 and hygiene, and found that the association of paratuberculosis with mastitis alters the ranking of 27 specific MAP control programs, but only slightly alters the cost-effectiveness of particular MAP 28 control components, as measured by the distribution of net present value of a representative U.S. 29 dairy operation. In particular, although testing and culling for MAP resulted in a reduction in 30 MAP incidence, that control led to lower net present value (NPV) per cow. When testing was 31 used, ELISA was more cost-effective than alternative testing regimes, especially if mastitis was 32 explicitly modeled as more likely in MAP-infected animals, but ELISA testing was only 33 significantly associated with higher NPV if mastitis was not included in the model at all. 34Additional hygiene was associated with a lower NPV per cow, although it lowered MAP 35 prevalence. Overall, the addition of an increased risk of mastitis in MAP-infected animals did not 36 change model recommendations as much as failing to consider mastitis at all. 37 Paratuberculosis, or Johne's Disease, is a chronic intestinal disease of ruminants caused by 40 infection with Mycobacterium avium subsp. paratuberculosis (MAP). Animals are usually 41 infected at a young age, with a variable and often extended latent period [1]. Infected animals 42 have lower milk production [2-9], decreased reproductive performance in later stages of disease 43 [6,10-12], and are often culled early [5,13]. It is difficult to control MAP in dairy herds; many 44 tests have poor diagnostic sensitivity [14], MAP persists in the environment for long periods of 45 time [15], paratuberculosis symptoms are slow to develop [16], and the available vaccines are 46 limited in distribution due to their cross-reaction with tuberculosis diagnostics [17]. 47 The debate over the economically optimal control method for MAP results from a wide range of 48 models and assumptions. Some studies have found test and culling to be consistently cost-49 effective [18,19], while others have found that cost-efficacy of test and cull required subsidized 50 testing costs [20] or only culling of animals with decreased milk production during MAP latency 51 [21]. Simulation models have identified cost-effective programs, such as q...

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Section: Methodsmentioning

confidence: 99%

Mastitis risk effect on the economic consequences of paratuberculosis control in dairy cattle: A stochastic modeling study

Chiu

Tauer

Grohn³

et al. 2019

Preprint

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“…When elimination is not possible, we have to rely on implementing the best herd-specific control strategies. Previous compartmental models have shown variable results for investigating infection dynamics(23,25,27), test-and-culling strategies(25,59), vaccination(24,60,61), and intermittent MAP shedding(30,43). None of these combined the individual animal’s information with herd management policy while fitting the model to real herd data, however.…”

Section: Methodsmentioning

confidence: 99%

“…In last two decades, different mathematical models have been developed on a within-herd scale to understand MAP transmission dynamics (23,24) and effectiveness of recommended control strategies (25–28). These models were simulated to assess the impact of contact structure on the MAP transmission (23), efficacy of test-and-cull policy (24,25,29,30), impact of low diagnostic test sensitivity in decision making (8,31), stopping some transmission pathways using hygiene improvement (32), improved calf management (33), impact of super-shedders in transmission(34,35), and economic efficacy of recommended programs (29). Most of these studies suggest that culling a test positive animal is an effective solution to reduce the prevalence.…”

Section: Introductionmentioning

confidence: 99%

A Data-driven Individual-based Model of Infectious Disease in Livestock Operation: A Validation Study for Paratuberculosis

Al-Mamun

Smith

Nigsch

et al. 2018

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24Chronic livestock diseases cause large financial loss and affect the animal health and welfare. 25Controlling these diseases mostly requires precise information on both individual animal and 26 population dynamics to inform farmer's decision. Mathematical models provide opportunities to 27 test different control and elimination options rather implementing them in real herds, but these 28 models require valid parameter estimation and validation. Fitting these models to data is a 29 difficult task due to heterogeneities in livestock processes. In this paper, we develop an 30 infectious disease modeling framework for a livestock disease (paratuberculosis) that is caused 31 by Mycobacterium avium subsp. paratuberculosis (MAP). Infection with MAP leads to reduced 32 milk production, pregnancy rates, and slaughter value and increased culling rates in cattle and 33 causes significant economic losses to the dairy industry in the US. These economic effects are 34 particularly important motivations in the control and elimination of MAP. In this framework, an 35 individual-based model (IBM) of a dairy herd was built and a MAP infection was integrated on 36 top of it. Once the model produced realistic dynamics of MAP infection, we implemented an 37 evaluation method by fitting it to data from three dairy herds from the Northeast region of the 38 US. The model fitting exercises used least-squares and parameter space searching methods to 39 obtain the best-fitted values of selected parameters. The best set of parameters were used to 40 model the effect of interventions. The results show that the presented model can complement 41 real herd statistics where the intervention strategies suggested a reduction in MAP but no 42 elimination was observed. Overall, this research not only provides a complete model for MAP 43 infection dynamics in a cattle herd, but also offers a method for estimating parameter by fitting 44 IBM models.45 46 47 48 Chronic livestock diseases like paratuberculosis (PTB) and bovine tuberculosis (bTB) are 49 commonly reported worldwide (1,2). Bovine TB is caused by the pathogen Mycobacterium bovis 50 (M. bovis) while PTB is caused by Mycobacterium avium subsp. paratuberculosis (MAP). In the 51UK, bTB has been spreading over the last two decades, putatively due to the presence of a 52 wildlife reservoir in badgers(3). In United States (US), 68% of dairy herds have apparently at least 53 one cow that is infected with MAP (4). Both diseases pose a potential threat not only to animal 54 health and production, but also to public health. Historically, bTB has been a contributor to 55 human TB cases worldwide and PTB infections in humans have been associated with an 56 increased risk of Crohn's disease in humans(5). Recently, it has been reported that these 57 diseases may induce additional collateral risks for public health due to dispensed antibiotics as 58 a treatment in some cases can potentially contribute to the spread of antibiotic resistance(6). 60In the US cattle industry, the cost of PTB was estimated at...

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“…The infection and testing model (Figure 1) have been previously described (Smith et al, 2015). This is a continuous-time model, and was simulated over 25 years using values representative of US dairy herds.…”

Section: Methodsmentioning

confidence: 99%

“…The findings of these analyses, therefore, were biased by the assumption that test-positive animals would eventually suffer from clinical disease, greatly decreased milk production, and decreased slaughter value. In addition, previous economic analyses (with one exception, (Robins et al, 2015)) have not considered adult infection, which molecular analysis has revealed to be a possibility (Pradhan et al, 2011) and which has been found to change simulation model outcomes (Smith et al, 2015). As hygiene programs are aimed at decreasing infectious pressure for calves, they are likely to be less effective than previously believed in the presence of adult infections.…”

Section: Introductionmentioning

confidence: 99%

Economic consequences of paratuberculosis control in dairy cattle: A stochastic modeling study

Smith

Al-Mamun

Gröhn

2017

Preventive Veterinary Medicine

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The cost of paratuberculosis to dairy herds, through decreased milk production, early culling, and poor reproductive performance, has been well-studied. The benefit of control programs, however, has been debated. A recent stochastic compartmental model for paratuberculosis transmission in US dairy herds was modified to predict herd net present value (NPV) over 25 years in herds of 100 and 1000 dairy cattle with endemic paratuberculosis at initial prevalence of 10% and 20%. Control programs were designed by combining 5 tests (none, fecal culture, ELISA, PCR, or calf testing), 3 test-related culling strategies (all test-positive, high-positive, or repeated positive), 2 test frequencies (annual and biannual), 3 hygiene levels (standard, moderate, or improved), and 2 cessation decisions (testing ceased after 5 negative whole-herd tests or testing continued). Stochastic dominance was determined for each herd scenario; no control program was fully dominant for maximizing herd NPV in any scenario. Use of the ELISA test was generally preferred in all scenarios, but no paratuberculosis control was highly preferred for the small herd with 10% initial prevalence and was frequently preferred in other herd scenarios. Based on their effect on paratuberculosis alone, hygiene improvements were not found to be as cost-effective as test-and-cull strategies in most circumstances. Global sensitivity analysis found that economic parameters, such as the price of milk, had more influence on NPV than control program-related parameters. We conclude that paratuberculosis control can be cost effective, and multiple control programs can be applied for equivalent economic results.

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A new compartmental model of Mycobacterium avium subsp. paratuberculosis infection dynamics in cattle

Cited by 23 publications

References 37 publications

Mastitis risk effect on the economic consequences of paratuberculosis control in dairy cattle: A stochastic modeling study

Mastitis risk effect on the economic consequences of paratuberculosis control in dairy cattle: A stochastic modeling study

A Data-driven Individual-based Model of Infectious Disease in Livestock Operation: A Validation Study for Paratuberculosis

Economic consequences of paratuberculosis control in dairy cattle: A stochastic modeling study

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