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Interpretation and Analysis of Individual Diagnostic Tests and Performance. Vet Clin North Am Food Anim Pract 2023; 39:1-19. [PMID: 36731991 DOI: 10.1016/j.cvfa.2022.10.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Diagnostic tests are performed daily by bovine practitioners at the individual and population level. At the individual level, they help not only for making a diagnosis, but can also serve to rule in or rule out a specific condition, monitor treatment response, establish a prognosis, or to determine infection status. Performing an individual diagnostic test is technical; however, its interpretation and contextualization requires medical and epidemiologic skills that veterinary practitioners are able to master. This article shows the added value of the context of test prescription and correct interpretation highlighting the central role of the veterinary practitioner.
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Scott CJ, de Mestre AM, Verheyen KL, Arango-Sabogal JC. Bayesian accuracy estimates and fit for purpose thresholds of cytology and culture of endometrial swab samples for detecting endometritis in mares. Prev Vet Med 2022; 209:105783. [DOI: 10.1016/j.prevetmed.2022.105783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 10/16/2022] [Accepted: 10/18/2022] [Indexed: 11/17/2022]
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Johnson P, McLeod L, Campbell J, Rousseau M, Larson K, Waldner C. Estimating the sensitivity and specificity of serum ELISA and pooled and individual fecal PCR for detecting Mycobacterium avium subspecies paratuberculosis in Canadian cow-calf herds using Bayesian latent class models. Front Vet Sci 2022; 9:937141. [PMID: 35968010 PMCID: PMC9372466 DOI: 10.3389/fvets.2022.937141] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Accepted: 07/11/2022] [Indexed: 12/03/2022] Open
Abstract
While Johne's disease (JD) is less common in beef than in dairy herds, consolidation is increasing transmission risk. Estimates of Mycobacterium avium spp. paratuberculosis (MAP) prevalence and test performance in cow-calf herds are needed to inform control programs. Objectives of this study included describing the prevalence of MAP in Canadian cow-calf herds and comparing the relative performance of a serum ELISA, pooled fecal PCR and individual fecal PCR using Bayesian latent class models, and to investigate factors associated with positive MAP tests. Blood and fecal samples (n = 3,171) were collected from 159 Canadian cow-calf herds. All samples were analyzed using serum ELISA and fecal PCR (pools of five samples) and a subset of 913 fecal samples were also tested with individual PCR. Based on latent class analysis, MAP prevalence was higher in eastern compared to western Canada for both animals {East, 3% [95% Credible Interval (CrI) 1–7%]; West, 1% [95% CrI 0.2–2%]} and herds [East, 15% (95% CrI 2–35%); West, 10% (95% CrI 1–26%), based on one or more positive results]. Sensitivity (Se) and specificity (Sp) for animal level individual PCR were 96% (95% CrI 80–100%) and 98% (95% CrI 96–100%), respectively followed by pooled PCR [Se = 54% (95% CrI 36–72%), Sp > 99.9% (95% CrI 99.8–100%)] and ELISA [Se = 36% (95% CrI 22–52%), Sp = 98% (95% CrI 96–99%)]. Based on 20 samples per herd, the herd level Se of ELISA was 79% (95% CrI 47–100%) (at least one positive sample) compared to 43% (95% CrI 14–94%) for pooled PCR. Herd-level Sp was 99% (95% CrI 96–100%) for pooled PCR and 90% (95% CrI 83–100%) for ELISA. Cows from herds with dairy cattle on farm and cows with symptoms of JD in the past 3 years were more likely to be MAP positive. Herds that had animals with JD symptoms in the previous 3 years and those with more breeding females were most likely to test positive for MAP. While serum ELISA can be effective for herd screening, PCR performed better for animal testing. Pooled PCR testing could be a less costly option; however, determining the most cost-effective approach will require further economic analysis.
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Affiliation(s)
- Paisley Johnson
- Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, Saskatoon, SK, Canada
| | - Lianne McLeod
- Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, Saskatoon, SK, Canada
| | - John Campbell
- Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, Saskatoon, SK, Canada
| | - Marjolaine Rousseau
- Département de Sciences Cliniques, Faculté de Médecine Vétérinaire, Université de Montréal, Saint-Hyacinthe, QC, Canada
| | - Kathy Larson
- Department of Agricultural and Resource Economics, College of Agriculture and Bioresources, Saskatoon, SK, Canada
| | - Cheryl Waldner
- Department of Large Animal Clinical Sciences, Western College of Veterinary Medicine, Saskatoon, SK, Canada
- *Correspondence: Cheryl Waldner
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Arango-Sabogal JC, Fecteau G, Doré E, Côté G, Roy JP, Wellemans V, Buczinski S. Bayesian accuracy estimates of environmental sampling for determining herd paratuberculosis infection status and its association with the within-herd individual fecal culture prevalence in Québec dairies. Prev Vet Med 2021; 197:105510. [PMID: 34695649 DOI: 10.1016/j.prevetmed.2021.105510] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 09/22/2021] [Accepted: 10/17/2021] [Indexed: 11/17/2022]
Abstract
The objectives of this retrospective analysis were to: 1) estimate the diagnostic sensitivity (Se) and specificity (Sp) of bacterial culture of environmental samples for determining Mycobacterium avium subsp. paratuberculosis (MAP) infection status in Québec dairies, using a Bayesian Latent Class Model (BLCM); and 2) determine the association between the number of positive environmental samples and the individual fecal culture (IFC) apparent and true MAP within-herd prevalence. Environmental and individual fecal samples were collected from 87 commercial dairy herds participating in previous research projects. Environmental samples included two composite samples of 20 g collected from different locations within each of the following sites: an area where manure from the majority of adult cattle accumulates, a manure storage area and another site of manure accumulation chosen by the veterinarian. Samples were cultured using the MGIT Para TB culture liquid media and the BACTEC MGIT 960 system. The Se and Sp of environmental sampling were estimated using a one-test-one-population BLCM. Herds were considered positive for environmental sampling if at least one out of the six samples collected was positive. The apparent and true IFC within-herd MAP prevalence estimates for each herd were obtained using a two-stage cluster BLCM, then merged in a single dataset with the environmental sample results. The association between the within-herd MAP prevalence results (apparent and true), and the number of positive environmental samples was assessed using a zero-inflated negative binomial (ZINB) model. In all BLCMs, median posterior estimates and 95 % Bayesian credible intervals (BCI) were obtained with OpenBUGS statistical freeware. Se and Sp of environmental sampling were 43.7 % (95 % BCI: 32.5-55.5) and 96.2 % (95 % BCI: 84.2-99.8), respectively. Overall, the number of positive environmental samples increased with the apparent and true MAP within-herd prevalence. The true prevalence was higher than the apparent prevalence for a given number of positive environmental samples. The probability of not observing a positive environmental sample decreased with the prevalence. Despite its imperfect accuracy, environmental sampling is an inexpensive and non-invasive sampling method to determine MAP infection status in tie-stall herds that can be used as a proxy to estimate the true within-herd prevalence. The absence of positive environmental samples in a single sampling visit is likely an indicator of a very low within-herd prevalence rather than being MAP exempt.
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Affiliation(s)
- Juan Carlos Arango-Sabogal
- Département de pathologie et microbiologie, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, J2S 2M2, Canada.
| | - Gilles Fecteau
- Département de sciences cliniques, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, J2S 2M2, Canada
| | - Elizabeth Doré
- Département de sciences cliniques, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, J2S 2M2, Canada
| | - Geneviève Côté
- Direction générale des laboratoires et de la santé animale, Ministère de l'Agriculture, des Pêcheries et de l'Alimentation du Québec, Québec, G1P 4S8, Canada
| | - Jean-Philippe Roy
- Département de sciences cliniques, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, J2S 2M2, Canada
| | - Vincent Wellemans
- Département de sciences cliniques, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, J2S 2M2, Canada
| | - Sébastien Buczinski
- Département de sciences cliniques, Faculté de médecine vétérinaire, Université de Montréal, Saint-Hyacinthe, Québec, J2S 2M2, Canada
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Alonso MN, Garcia VS, Moyano RD, Romero MA, Gugliotta LM, Travería GE, Romano MI, Gonzalez VDG. New and rapid strategies for the diagnosis of bovine paratuberculosis "in situ" using latex particles. J Immunol Methods 2021; 496:113085. [PMID: 34157319 DOI: 10.1016/j.jim.2021.113085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 05/20/2021] [Accepted: 06/13/2021] [Indexed: 11/17/2022]
Abstract
The chemical coupling of a protoplasmatic antigen from Mycobacterium avium subsp. paratubeculosis onto core-shell carboxylated particles was investigated with the aim of producing latex-protein complexes to be used in immunoagglutination assays capable of detecting bovine paratuberculosis disease. For this purpose, sensitizations were carried out using both colored and not colored carboxylated latexes as well as the protoplasmatic antigen at pH close to its isoelectric point to favor the antigenic protein to approach the particle surface. In all cases, higher fractions of proteins were chemically-bound to carboxyl groups on the surface of the particles. The assessment of the performance of the visual immunoagglutination assays consisted of evaluating 111 sera from healthy and infected bovines with Mycobacterium avium subsp. paratuberculosis. Complexes obtained from the colored latex allowed an acceptable visual discrimination between the studied positive and negative sera. Most of the positive samples showed strong to very strong agglutination and only a few samples reacted weakly, i.e. a sensitivity of 70%. The specificity of the assay, on the other hand, was 86%. Therefore, this rapid detection technique allows an easy and inexpensive identification of animals possibly infected with paratuberculosis "in situ" in the herds.
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Affiliation(s)
- M N Alonso
- Instituto de Agrobiotecnología y Biología Molecular (INTA - CONICET), Hurlingham, Buenos Aires, Argentina
| | - V S Garcia
- Instituto de Desarrollo Tecnológico para la Industria Química (CONICET - UNL), Santa Fe, Argentina
| | - R D Moyano
- Instituto de Agrobiotecnología y Biología Molecular (INTA - CONICET), Hurlingham, Buenos Aires, Argentina
| | - M A Romero
- Centro de Diagnóstico e Investigaciones Veterinarias (FCV-UNLP), Argentina
| | - L M Gugliotta
- Instituto de Desarrollo Tecnológico para la Industria Química (CONICET - UNL), Santa Fe, Argentina; Facultad de Ingeniería Química, Universidad Nacional del Litoral, Santa Fe, Argentina
| | - G E Travería
- Centro de Diagnóstico e Investigaciones Veterinarias (FCV-UNLP), Argentina
| | - M I Romano
- Instituto de Agrobiotecnología y Biología Molecular (INTA - CONICET), Hurlingham, Buenos Aires, Argentina
| | - V D G Gonzalez
- Instituto de Desarrollo Tecnológico para la Industria Química (CONICET - UNL), Santa Fe, Argentina; Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral, Santa Fe, Argentina.
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Elsohaby I, Arango-Sabogal JC, McClure JT, Dufour S, Buczinski S, Keefe GP. Accuracy of direct and indirect methods for assessing bovine colostrum quality using a latent class model fit within a Bayesian framework. J Dairy Sci 2021; 104:4703-4714. [PMID: 33612236 DOI: 10.3168/jds.2020-19231] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 12/17/2020] [Indexed: 11/19/2022]
Abstract
Feeding high-quality colostrum is essential for calf health and future productivity. Therefore, accurate assessment of colostrum quality is a key component of dairy farm management plans. Direct and indirect methods are available for assessment of colostrum quality; however, the indirect methods are rapid, inexpensive, and can be performed under field settings. A hierarchical latent class model fit within a Bayesian framework was used to estimate the sensitivity (Se) and specificity (Sp) of the radial immunodiffusion (RID) assay, transmission infrared (TIR) spectroscopy, and digital Brix refractometer for the assessment of low-quality bovine colostrum in Atlantic Canada dairy herds. The secondary objective of the study was to describe the distribution of herd prevalence of low-quality colostrum. Colostrum quality of 591 samples from 42 commercial Holstein dairy herds in 4 Atlantic Canada provinces was assessed using RID, TIR spectroscopy, and digital Brix refractometer. The accuracy of all tests at different Brix value thresholds was estimated using Bayesian latent class models to obtain posterior estimates [medians and 95% Bayesian credibility intervals (95% BCI)] for each parameter. Using a threshold of <23% for digital Brix refractometer and <50 g/L for RID and TIR spectroscopy, median (95% BCI) Se estimates were 73.2 (68.4-77.7), 86.2 (80.6-91.0), and 91.9% (89.0-94.2), respectively. Median (95% BCI) Sp estimates were 85.2% (81.0-88.9) for digital Brix refractometer, 99.4% (97.0-100) for RID, and 90.7% (87.8-93.2) for TIR spectroscopy. Median (95% BCI) within-herd low-quality colostrum prevalence was estimated at 32.5% (27.9-37.4). In conclusion, using digital Brix refractometer at a Brix threshold of <23% could reduce feeding of low-quality colostrum to calves and improve colostrum and calf management practices in Atlantic Canada dairy herds. The TIR spectroscopy showed high Se in detection of low-quality colostrum. However, the RID assay, which is used as the reference test in several studies, showed limited Se for detection of low-quality colostrum.
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Affiliation(s)
- I Elsohaby
- Department of Animal Medicine, Faculty of Veterinary Medicine, Zagazig University, Zagazig City 44511, Sharkia Province, Egypt; Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PEI, Canada C1A 4P3.
| | - J C Arango-Sabogal
- One Health and Veterinary Innovative Research and Development Group, School of Veterinary Medicine, University of Antioquia, Medellin, Colombia 050034
| | - J T McClure
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PEI, Canada C1A 4P3
| | - S Dufour
- Department of Pathology and Microbiology, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC, Canada J2S 2M2
| | - S Buczinski
- Département des Sciences Cliniques, Faculty of Veterinary Medicine, University of Montreal, Saint-Hyacinthe, QC, Canada J2S 2M2
| | - G P Keefe
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PEI, Canada C1A 4P3
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