Sensitivity of environmental sampling methods for detecting Salmonella Enteritidis in commercial laying flocks relative to the within-flock prevalence.
The objective of this study was to estimate the sensitivity of three different sampling/testing methodologies for the detection of Salmonella Enteritidis in commercial egg-laying flocks relative to the within-flock prevalence. The following methods were compared on 21 farms: (1) The European Union (EU) baseline survey method (five faecal and two dust samples); (2) an in-house method that involved collecting 10 dust and 10 faecal samples into jars with buffered peptone water, and (3) a method involving single samples of pooled faeces and dust that has been adopted as a monitoring method for the National Control Programme across the EU (the NCP method). Testing of individual bird ovaries/oviduct and caeca was carried out on each flock, and the sensitivity of each sampling method was estimated relative to the within-flock prevalence using Bayesian methods. Results showed that the sensitivity of all the sampling methods increased as the within-flock prevalence increased, and that all were more efficient than individual bird sampling for detection of S. Enteritidis in commercial flocks. The in-house method was the most sensitive of the methods compared, with a 98% power to detect a 0.1% prevalence, and the NCP method the least sensitive, with a 93% power to detect a prevalence of 20%.
Arnold
M E
ME
Centre for Epidemiology and Risk Analysis, Veterinary Laboratories Agency, Sutton Bonington, UK. m.arnold@vla.defra.gsi.gov.uk
Carrique-Mas
J J
JJ
Davies
R H
RH
D000818:Animals; D002645:Chickens; D004391:Dust; D004784:Environmental Monitoring; D005243:Feces / Q000382:microbiology; D005260:Female; D006799:Housing, Animal; D010053:Ovary / Q000382:microbiology; D010057:Oviducts / Q000382:microbiology; D011201:Poultry Diseases / Q000382:microbiology*; D012481:Salmonella Infections, Animal / Q000382:microbiology*; D012477:Salmonella enteritidis; D012680:Sensitivity and Specificity
D004391:Dust