Field estimation of the flock-level diagnostic specificity of an enzyme-linked immunosorbent assay for Avian metapneumovirus antibodies in turkeys

Claudia Muñoz-Zanzi, Darrell Trampel, Tim Hanson, Kristen Harrison, Sagar Goyal, Roberto Cortinas, Dale Lauer

Research output: Contribution to journalArticlepeer-review

Abstract

Routine serologic testing for Avian melapneumovirus (AMPV) infection of turkey flocks at slaughter is currently being used to monitor changes in the occurrence of AMPV infection in endemic areas and can also be used to detect the emergence of infection in currently unaffected areas. Because of the costs associated with false-positive results, particularly in areas that are free of AMPV infection, there is a need to obtain improved estimates of flock-level specificity (SP). The objective of this study was to estimate flock-level SP of a program to monitor AMPV infection in turkey flocks at processing using a standard enzyme-linked immunosorbent assay (ELISA). A study was carried out in which 37 AMPV-free flocks from 7 Midwest operations were followed serologically. Six percent, 3%, and 0.2% of total samples tested AMPV positive at 8 weeks, 12 weeks, and at processing, respectively. Overall, flock-level SP increased as the cutoff increased and as age increased. Flock-level SP at processing was 97%, if a cutoff of 1 was used (the flock was classified as positive if at least 1 sample tested positive), and 100%, if any other cutoff was used. Administration of antibiotics (P = 0.02) and vaccination for Bordetella avium (P = 0.08) were positively associated with the probability of (false) positive test results. These findings suggest possible cross-reactions with other infections and highlight the need to consider variable diagnostic performance depending on farm conditions.

Original languageEnglish (US)
Pages (from-to)240-243
Number of pages4
JournalJournal of Veterinary Diagnostic Investigation
Volume21
Issue number2
DOIs
StatePublished - Mar 2009

Bibliographical note

Funding Information:
Acknowledgements . The authors thank the turkey producers that participated in the study and the laboratory personnel at the Iowa and Minnesota Veterinary Diagnostic Laboratories and the Minnesota Poultry Testing Laboratory for sample processing and testing. This study was funded by Minnesota Turkey Research and Promotion Council (Project 2005–05) and a U.S. Department of Agriculture-Cooperative State Research, Education, and Extension Service Special Research Grant to the Midwest Poultry Consortium.

Keywords

  • Avian metapneumovirus
  • Diagnostics
  • Enzyme-linked immunosorbent assay
  • Specificity
  • Turkeys

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