Modelling coccidial infection in chickens: Emphasis on vaccination by in-feed delivery of oocysts

Parry, S H; Barratt, M.E.J.; Jones, Simon R. M.; McKee, Sean; Murray, J. D.

doi:10.1016/s0022-5193(05)80661-7

Cited by 16 publications

(11 citation statements)

References 14 publications

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“…The model Eimeria lifecycle ( Figure 1) followed the foundational structure developed by other authors (26,(28)(29)(30). In short, a recursive system of calculations operating at one-day time steps estimates daily change in pathogen lifecycle stages (x) in a FIGURE 1 | Lifecycle of Eimeria species.…”

Section: Eimeria Lifecyclementioning

confidence: 99%

“…The development of coccidiosis modeling has reflected the complexity of disease progression and pathogenesis. Parry et al (26) described a recursive mathematical model of the E. tenella life cycle focused on tracking the development of immunity. Henken et al (27,28) took a similar recursive approach to assess the economic impact of differing levels of environmental contamination with E. acervulina on broiler production systems.…”

Section: Introductionmentioning

confidence: 99%

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Revisiting the Economic Impacts of Eimeria and Its Control in European Intensive Broiler Systems With a Recursive Modeling Approach

et al. 2020

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Ionophore compounds active against Eimeria species are widely used in intensive broiler systems and have formed the backbone of coccidiosis control for almost 50 years. Producers, however, are under pressure to reduce ionophore use due to consumer concerns over antimicrobial usage in food animals, and antimicrobial resistance. Moreover, current vaccines against Eimeria are commonly considered to be less cost-effective in intensive broiler systems, especially in Europe where attenuated live vaccines are used. An economic assessment of the impact of Eimeria and the disease coccidiosis, including the cost implications of different efficacies of control, is therefore timely to provide evidence for industry and policy development. A mechanistic model of broiler production under varying infection and control states was used to construct a dataset from which system productivity can be measured. Coccidiosis impact increased rapidly as control efficacy decreased. In the total absence of control, median impact was found to maximize at between e2.55 and e2.97 in lost production per meter squared of broiler house over a 33 day growing period. Coccidiosis remains a major risk to intensive broiler systems and the model developed allows investigation of issues related to coccidiosis control, antimicrobial use and the development of antimicrobial resistance.

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Section: Eimeria Lifecyclementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Revisiting the Economic Impacts of Eimeria and Its Control in European Intensive Broiler Systems With a Recursive Modeling Approach

et al. 2020

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“…1). Because sporulation, which is required for an oocyst to become infectious, takes about 1–2 days (Parry et al 1992; Graat et al 1994; Waldenstedt et al 2001; Allen and Fetterer, 2002; McDougald, 2003), the transition from z to v takes one time step in the model. We consider the average infection dynamics in a population of chickens by assuming that this is equivalent to all chickens undergoing identical infection dynamics: Here, a 0 is the uptake probability per oocyst, per time unit, and a proportion σ of the oocysts that are not ingested, survive to the next time step.…”

Section: The Modelmentioning

confidence: 99%

A model for the dynamics of a protozoan parasite within and between successive host populations

Klinkenberg

Heesterbeek

2007

Parasitology

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S U M M A R YParasite-host systems often include an obligatory environmental stage in the parasite life-cycle, which can be transmitted between successive populations. Complexity even increases if immunity only gradually develops upon re-infection. For a better understanding of such systems we study Eimeria spp. in chickens, a protozoan parasite transmitted through oocysts on the floor. This paper deals with dynamics within and between successive cohorts of chickens by coupling a within-host description of the parasite life-cycle (with immunity) to re-uptake of oocysts from the environment. First the initial environmental oocyst level is related to the maximum infection load within a cohort, as a measure of production damage, from which we conclude that minimum damage levels can be observed with intermediate oocyst levels. Then we relate the initial to the final oocyst level of a cohort, and study the dynamics between cohorts in relation to an oocyst cleaning efficiency after each cohort. The resulting unstable dynamics lead to the conclusion that it will often be impossible to minimize damage by repeatedly cleaning with the same effort: it may be necessary to artificially increase oocyst levels in the shed before each chicken cohort.

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“…Several attempts have been made to quantify the consequences of coccidiosis in chickens. Eimeria lifecycles have been modelled for several parasite species, assessing rates of replication and/or associated pathology [7][8][9][10][11][12]. The financial cost has been estimated for countries including Ethiopia, India, Romania and the UK [4,[13][14][15], with a model published by Williams being most comprehensive and most widely referenced [16].…”

Section: Introductionmentioning

confidence: 99%

Re-calculating the cost of coccidiosis in chickens

Blake

Knox

Dehaeck³

et al. 2020

Vet Res

391

242

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Coccidiosis, caused by Eimeria species parasites, has long been recognised as an economically significant disease of chickens. As the global chicken population continues to grow, and its contribution to food security intensifies, it is increasingly important to assess the impact of diseases that compromise chicken productivity and welfare. In 1999, Williams published one of the most comprehensive estimates for the cost of coccidiosis in chickens, featuring a compartmentalised model for the costs of prophylaxis, treatment and losses, indicating a total cost in excess of £38 million in the United Kingdom (UK) in 1995. In the 25 years since this analysis the global chicken population has doubled and systems of chicken meat and egg production have advanced through improved nutrition, husbandry and selective breeding of chickens, and wider use of anticoccidial vaccines. Using data from industry representatives including veterinarians, farmers, production and health experts, we have updated the Williams model and estimate that coccidiosis in chickens cost the UK £99.2 million in 2016 (range £73.0–£125.5 million). Applying the model to data from Brazil, Egypt, Guatemala, India, New Zealand, Nigeria and the United States resulted in estimates that, when extrapolated by geographical region, indicate a global cost of ~ £10.4 billion at 2016 prices (£7.7–£13.0 billion), equivalent to £0.16/chicken produced. Understanding the economic costs of livestock diseases can be advantageous, providing baselines to evaluate the impact of different husbandry systems and interventions. The updated cost of coccidiosis in chickens will inform debates on the value of chemoprophylaxis and development of novel anticoccidial vaccines.

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Modelling coccidial infection in chickens: Emphasis on vaccination by in-feed delivery of oocysts

Cited by 16 publications

References 14 publications

Revisiting the Economic Impacts of Eimeria and Its Control in European Intensive Broiler Systems With a Recursive Modeling Approach

Revisiting the Economic Impacts of Eimeria and Its Control in European Intensive Broiler Systems With a Recursive Modeling Approach

A model for the dynamics of a protozoan parasite within and between successive host populations

Re-calculating the cost of coccidiosis in chickens

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