title: Rapid testing leads to the underestimation of the scrapie prevalence in an affected sheep and goat flock.
abstract: To obtain a more detailed understanding of the prevalence of classical scrapie infections in a heavily affected German sheep flock (composed of 603 sheep and 6 goats), we analysed 169 sheep and 6 goats that carried the genotypes susceptible to the disease and that were therefore culled following discovery of the index case. The initial tests were performed using the Biorad TeSeE ELISA and reactive results were verified by official confirmatory methods (OIE-immunoblot and/or immunohistochemistry (IHC)) to demonstrate the deposition of scrapie-associated PrP(Sc) in the brain stem (obex). This approach led to the discovery of 40 additional subclinically scrapie-infected sheep. Furthermore, peripheral lymphatic and nervous tissue samples of the 129 sheep and 6 goats with a negative CNS result were examined by IHC in order to identify any preclinical infections which had not already spread to the central nervous system (CNS). Using this approach we found 13 additional sheep with PrP(Sc) depositions in the gut-associated lymph nodes (GALT) as well as in the enteric nervous system. Moreover, in most of these cases PrP(Sc) was also deposited in the spleen and in the retropharyngeal and superficial cervical lymph nodes. Taken together, these results show a 30.3% infection prevalence in this scrapie-affected flock. Almost 7.4% of the infected animals harboured PrP(Sc) exclusively in the peripheral lymphatic and nervous tissue and were therefore missed by the currently used testing strategy.
authors.affiliation: Friedrich-Loeffler-Institut, Institute for Novel and Emerging Diseases, Insel Riems, Germany.
authors.forename: Claudia
authors.initials: C
authors.lastname: Reckzeh
authors.forename: Christine
authors.initials: C
authors.lastname: Hoffmann
authors.forename: Anne
authors.initials: A
authors.lastname: Buschmann
authors.forename: Silke
authors.initials: S
authors.lastname: Buda
authors.forename: Klaus-Dieter
authors.initials: KD
authors.lastname: Budras
authors.forename: Karl-Friedrich
authors.initials: KF
authors.lastname: Reckling
authors.forename: Steffi
authors.initials: S
authors.lastname: Bellmann
authors.forename: Hartmut
authors.initials: H
authors.lastname: Knobloch
authors.forename: Georg
authors.initials: G
authors.lastname: Erhardt
authors.forename: Reinhard
authors.initials: R
authors.lastname: Fries
authors.forename: Martin H
authors.initials: MH
authors.lastname: Groschup
mesh_terms: D000818:Animals; D001933:Brain Stem / Q000737:chemistry* / Q000378:metabolism; D015331:Cohort Studies; D003937:Diagnosis, Differential; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods / Q000662:veterinary; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D005838:Genotype; D015511:Goat Diseases / Q000175:diagnosis / Q000453:epidemiology* / Q000378:metabolism; D006041:Goats; D007150:Immunohistochemistry / Q000662:veterinary; D008221:Lymphoid Tissue / Q000737:chemistry / Q000378:metabolism; D008297:Male; D009928:Organ Specificity; D017933:Peripheral Nervous System; D018620:PrPSc Proteins / Q000302:isolation & purification*; D015995:Prevalence; D012608:Scrapie / Q000175:diagnosis* / Q000453:epidemiology* / Q000378:metabolism; D012680:Sensitivity and Specificity; D012756:Sheep
chemical_list: D018620:PrPSc Proteins