Prevalence of paratuberculosis (Johne's disease) in the Belgian cattle population

Boelaert, Frank; Walravens, Karl; Biront, P.; Vermeersch, J. P.; Berkvens, Dirk; Godfroid, Jacques

doi:10.1016/s0378-1135(00)00312-6

Cited by 62 publications

(36 citation statements)

References 15 publications

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“…In New-York State (USA), Obasanjo et al [14] estimate this within-herd prevalence to 5.2% using faecal culture on whole herds. In Belgium, the median within-herd prevalence estimated by Boelaert et al [4] is 7% (quartiles 4%-12%), based on an ELISA serological survey (sensitivity estimated to 0.45, specificity estimated to 0.99). Keeping in mind the described biases in withinherd prevalence estimation [4], the results of our models are in agreement with these relatively low estimates.…”

Section: Discussionmentioning

confidence: 93%

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A deterministic and stochastic simulation model for intra-herd paratuberculosis transmission

Pouillot¹,

Dufour²,

Durand³

2004

Vet. Res.

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-In France, the considerable economic losses due to paratuberculosis introduction in cattle herds may justify the development of a herd-level certification procedure. For a cost/benefit analysis purpose, a simple deterministic and stochastic simulation model for intra-herd paratuberculosis transmission has been developed to evaluate the economic consequences of the purchase of a single infected heifer in a French average herd. The values of the epidemiological parameters were provided by a panel of French paratuberculosis experts. The results were in adequacy with field observations. A sensitivity analysis was conducted. The model was however difficult to validate rigorously, since few data on the intra-herd paratuberculosis true prevalence level are currently available. paratuberculosis / stochastic model / deterministic model / sensitivity analysis

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Section: Discussionmentioning

confidence: 93%

“…Little data exist on the "true" within-herd prevalence (i.e. corrected for test diagnostic performance) of paratuberculosis [4]. Moreover, corrections of the estimated prevalence from literature data are almost impossible since paratuberculosis test sensitivities are described as highly different according to the infection stage [18,19].…”

Section: Discussionmentioning

confidence: 99%

A deterministic and stochastic simulation model for intra-herd paratuberculosis transmission

Pouillot¹,

Dufour²,

Durand³

2004

Vet. Res.

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“…This approach resulted in an estimated true herd prevalence of M. avium subsp. paratuberculosis infection of 6% (6). Dairy cattle usually start fecal shedding at 2 years of age and develop clinical symptoms around 4 years of age.…”

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confidence: 99%

Members of the 30- to 32-Kilodalton Mycolyl Transferase Family (Ag85) from Culture Filtrate of Mycobacterium avium subsp. paratuberculosis Are Immunodominant Th1-Type Antigens Recognized Early upon Infection in Mice and Cattle

et al. 2006

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On the basis of DNA-DNA hybridization and numerical taxonomy analysis, the mycobacterial species Mycobacterium avium is subdivided into three subspecies, M. avium subsp. avium, M. avium subsp. paratuberculosis, and M. avium subsp. silvaticum, which share extensive sequence identity (8). Nevertheless, these subspecies can be differentiated from each other on the basis of host range, mycobactin dependence, and the presence of specific insertion elements (17). M. avium subsp. paratuberculosis causes Johne's disease, a severe gastroenteritis in ruminants, with a significant impact on the agricultural economy, particularly the dairy industry (17). In the Belgian cattle population, paratuberculosis prevalence was determined by a serological survey, conducted from December 1997 to March 1998. This approach resulted in an estimated true herd prevalence of M. avium subsp. paratuberculosis infection of 6% (6). Dairy cattle usually start fecal shedding at 2 years of age and develop clinical symptoms around 4 years of age. Infection with M. avium subsp. paratuberculosis is commonly acquired early in life via the fecal-oral route through the ingestion of contaminated colostrum, milk, water, or feed (46) and possibly through intrauterine transmission (42). M. avium subsp. paratuberculosis is extremely robust, and bacteria were reported to survive up to 250 days in water and feces and on pastures (27).Cell-mediated immune responses seem to control the initial infection for a sustained period of time, and clinical symptoms only appear in cows after a number of years, often after the first or second calving, possibly because of enhanced intracellular multiplication of M. avium subsp. paratuberculosis organisms caused by alterations in the hormonal milieu (15). Decreased cell-mediated responses are likely related to a loss of antigen-specific CD4 ϩ T cells, which is most prominent in the ileum lesions from symptomatic animals (24). Also, Khalifeh et al. demonstrated that transforming growth factor ␤ and interleukin-10 (IL-10) mRNA levels are higher in cows that have progressed to the clinical stage of the disease, compared to subclinically infected or healthy cows (23). It is not clear for the moment, whether this reflects a shift from a Th1-to a Th2-biased immune response or rather the development of a regulatory T-cell circuit (10). Vaccines consisting of whole killed or attenuated live M. avium subsp. paratuberculosis bacilli can provide partial protection by delaying fecal shedding and reducing the number of clinically affected animals, but they do not protect against infection. In the context of bovine tuberculosis (M. bovis) control and eradication programs, it is worth mentioning that animals immunized with these paratuberculosis vaccines develop positive reactions in the tuberculin skin test (the reference bovine tuberculosis detection method), and therefore paratuberculosis vaccination is subject to approval by

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“…As the probability SE (SP ) of a truly positive (negative) individual sample to test positive (negative) is less than 100%, the probability SE P (SP P ) of a truly positive (negative) pool of samples to test positive (negative) will equally be less than 100% (Munoz-Zanzi et al, 2006). The relationship between the individual and pool test characteristics are given by Boelaert et al (2000):…”

Section: Mathematical Basis Of Pool Testingmentioning

confidence: 99%

Estimating the prevalence of infections in vector populations using pools of samples

Speybroeck

Williams

Lafia

et al. 2012

Medical Vet Entomology

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Abstract. Several statistical methods have been proposed for estimating the infection prevalence based on pooled samples, but these methods generally presume the application of perfect diagnostic tests, which in practice do not exist. To optimize prevalence estimation based on pooled samples, currently available and new statistical models were described and compared. Three groups were tested: (a) Frequentist models, (b) Monte Carlo Markov-Chain (MCMC) Bayesian models, and (c) Exact Bayesian Computation (EBC) models. Simulated data allowed the comparison of the models, including testing the performance under complex situations such as imperfect tests with a sensitivity varying according to the pool weight. In addition, all models were applied to data derived from the literature, to demonstrate the influence of the model on real-prevalence estimates. All models were implemented in the freely available R and OpenBUGS software and are presented in Appendix S1. Bayesian models can flexibly take into account the imperfect sensitivity and specificity of the diagnostic test (as well as the influence of pool-related or external variables) and are therefore the method of choice for calculating population prevalence based on pooled samples. However, when using such complex models, very precise information on test characteristics is needed, which may in general not be available.

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Prevalence of paratuberculosis (Johne's disease) in the Belgian cattle population

Cited by 62 publications

References 15 publications

A deterministic and stochastic simulation model for intra-herd paratuberculosis transmission

A deterministic and stochastic simulation model for intra-herd paratuberculosis transmission

Members of the 30- to 32-Kilodalton Mycolyl Transferase Family (Ag85) from Culture Filtrate of Mycobacterium avium subsp. paratuberculosis Are Immunodominant Th1-Type Antigens Recognized Early upon Infection in Mice and Cattle

Estimating the prevalence of infections in vector populations using pools of samples

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