Field performance of two rapid screening tests in active surveillance of transmissible spongiform encephalopathies in small ruminants

Seuberlich, Torsten; Doherr, Marcus; Botteron, Catherine; Nicolier, Alexandra; Schwermer, H.; Brunisholz, H.; Heim, D.; Zurbriggen, Andreas (2009). Field performance of two rapid screening tests in active surveillance of transmissible spongiform encephalopathies in small ruminants. Journal of veterinary diagnostic investigation, 21(1), pp. 97-101. Columbia, Mo.: American Association of Veterinary Laboratory Diagnosticians AAVLD 10.1177/104063870902100114

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Recently, screening tests for monitoring the prevalence of transmissible spongiform encephalopathies specifically in sheep and goats became available. Although most countries require comprehensive test validation prior to approval, little is known about their performance under normal operating conditions. Switzerland was one of the first countries to implement 2 of these tests, an enzyme-linked immunosorbent assay (ELISA) and a Western blot, in a 1-year active surveillance program. Slaughtered animals (n = 32,777) were analyzed in either of the 2 tests with immunohistochemistry for confirmation of initial reactive results, and fallen stock samples (n = 3,193) were subjected to both screening tests and immunohistochemistry in parallel. Initial reactive and false-positive rates were recorded over time. Both tests revealed an excellent diagnostic specificity (>99.5%). However, initial reactive rates were elevated at the beginning of the program but dropped to levels below 1% with routine and enhanced staff training. Only those in the ELISA increased again in the second half of the program and correlated with the degree of tissue autolysis in the fallen stock samples. It is noteworthy that the Western blot missed 1 of the 3 atypical scrapie cases in the fallen stock, indicating potential differences in the diagnostic sensitivities between the 2 screening tests. However, an estimation of the diagnostic sensitivity for both tests on field samples remained difficult due to the low disease prevalence. Taken together, these results highlight the importance of staff training, sample quality, and interlaboratory comparison trials when such screening tests are implemented in the field.

Item Type:

Journal Article (Original Article)

Division/Institute:

05 Veterinary Medicine > Department of Clinical Veterinary Medicine (DKV) > DVK - Clinical Research (discontinued)
05 Veterinary Medicine > Department of Clinical Research and Veterinary Public Health (DCR-VPH) > Veterinary Public Health Institute
05 Veterinary Medicine > Department of Clinical Research and Veterinary Public Health (DCR-VPH) > Experimental Clinical Research
05 Veterinary Medicine > Department of Clinical Research and Veterinary Public Health (DCR-VPH)

UniBE Contributor:

Seuberlich, Torsten; Doherr, Marcus; Botteron, Catherine; Nicolier, Alexandra and Zurbriggen, Andreas

ISSN:

1040-6387

Publisher:

American Association of Veterinary Laboratory Diagnosticians AAVLD

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 15:25

Last Modified:

16 Feb 2015 15:57

Publisher DOI:

10.1177/104063870902100114

Web of Science ID:

000262793800014

URI:

https://boris.unibe.ch/id/eprint/38250 (FactScience: 220769)

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