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Economic costs associated with two testing strategies for screening feeder calves for persistent infection with bovine viral diarrhea virus

Robert L. LarsonDepartment of Medicine and Surgery, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211.

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 DVM, PhD, DACT
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Robert B. MillerMissouri Institute for Cattle, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211.

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Steve B. KleiboekerVeterinary Medical Diagnostic Laboratory, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211.

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Margaret A. MillerVeterinary Medical Diagnostic Laboratory, College of Veterinary Medicine, University of Missouri, Columbia, MO 65211.
Present address is the Animal Disease Diagnostic Laboratory, School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907.

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Brad J. WhitePerry County Veterinary Hospital, 908 S Kingshighway, Perryville, MO 63775.
Present address is Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS 39762.

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Abstract

Objective—To develop partial budgets of the economic costs of 2 test strategies for screening cattle for persistent infection with bovine viral diarrhea virus (BVDV).

Design—Partial budget analysis.

Animals—938 calves arriving at 2 stocker operations.

Procedure—Calves were tested to determine prevalence of persistent BVDV infection. Test strategies that were evaluated included a single-test strategy consisting of immunohistochemical staining of skin biopsy specimens from all animals and a 2-test strategy consisting of polymerase chain reaction (PCR) assaying of pooled blood samples followed by immunohistochemical staining of skin biopsy specimens from animals in pools for which assay results were positive. Breakeven costs (ie, cost of persistent BVDV infection per animal necessary to justify whole-herd diagnostic testing) associated with each test strategy were calculated as a function of disease prevalence and test cost.

Results—Apparent prevalence of persistent BVDV infection was 0.32%. Sensitivity and specificity of the PCR assay for pooled samples were 100% and 89.7%, respectively. Regardless of the prevalence of persistent BVDV infection, the break-even cost for the 2-test strategy was lower than the break-even cost for the single-test strategy. However, the economic advantage was greatest when prevalence was low.

Conclusions and Clinical Relevance—Results suggest that using a 2-test strategy to screen cattle for persistent BVDV infection, whereby the first test involves PCR assaying of pooled samples and the second involves immunohistochemical testing only of those animals represented in pooled samples with positive assay results, will reduce the cost of screening incoming feedlot cattle, compared with immunohistochemical testing of all animals. (J Am Vet Med Assoc 2005;226:249–254)

Abstract

Objective—To develop partial budgets of the economic costs of 2 test strategies for screening cattle for persistent infection with bovine viral diarrhea virus (BVDV).

Design—Partial budget analysis.

Animals—938 calves arriving at 2 stocker operations.

Procedure—Calves were tested to determine prevalence of persistent BVDV infection. Test strategies that were evaluated included a single-test strategy consisting of immunohistochemical staining of skin biopsy specimens from all animals and a 2-test strategy consisting of polymerase chain reaction (PCR) assaying of pooled blood samples followed by immunohistochemical staining of skin biopsy specimens from animals in pools for which assay results were positive. Breakeven costs (ie, cost of persistent BVDV infection per animal necessary to justify whole-herd diagnostic testing) associated with each test strategy were calculated as a function of disease prevalence and test cost.

Results—Apparent prevalence of persistent BVDV infection was 0.32%. Sensitivity and specificity of the PCR assay for pooled samples were 100% and 89.7%, respectively. Regardless of the prevalence of persistent BVDV infection, the break-even cost for the 2-test strategy was lower than the break-even cost for the single-test strategy. However, the economic advantage was greatest when prevalence was low.

Conclusions and Clinical Relevance—Results suggest that using a 2-test strategy to screen cattle for persistent BVDV infection, whereby the first test involves PCR assaying of pooled samples and the second involves immunohistochemical testing only of those animals represented in pooled samples with positive assay results, will reduce the cost of screening incoming feedlot cattle, compared with immunohistochemical testing of all animals. (J Am Vet Med Assoc 2005;226:249–254)