Commercial Broiler Vaccination, United Kingdom - ComBVacUK
The prevalence of Campylobacter positive flocks in EU during 2008 varied widely from 2.0% to 100.0% between Member States. In the UK, the estimated prevalence for Campylobacter in broiler flocks was 75% and on broiler carcasses was 86% [EFSA, 2010]. These values were higher than the EU mean prevalence values of 71% and 77% respectively. However, quantitative data indicated that 42% of the UK positive samples contained less that 100 cfu/g, 31% between 100 and 1000 cfu/g and 27% contained more than 1000 cfu/g.
The quantification of the model used on this web-site is based on a survey from the United Kingdom [Lawes et al, 2012]. These authors conducted an investigation on the prevalence of Campylobacter in broiler flocks sent for slaughter to thirty-seven abattoirs in the UK during 2007 - 2009. Their results indicated that 79.2% of broilers carried Campylobacter, the majority of isolates being C. jejuni.
Furthermore, an epidemiological investigation demonstrated that previous partial depopulation, higher recent mortality level, increasing bird age and slaughter during summer or autumn were risk factors significantly associated with Campylobacter infection of broilers.
Quantitative data reported in this study have been used to calculate probabilities for the ComBVac UK model. A baseline level of 20% has been used for the calculations. A UK report indicates that the proposed UK target for 2015 aims to reduce the percentage of chickens with more than 1000 cfu/g from a baseline of 27% in 2008 to 10% in 2015 [Anon, 2010].
Economic data included in the CamBVac UK model has been based on data from a Farm Business Survey [Crane et al, 2010].
The structure of the model used on this web-page is based on the generic model for decision making on vaccination of poultry presented in [Madsen et al, 2012].
Farm Characteristics, System Variables and Observations
| What is the flock history (previous campylobacter level)? | |
| Depopulation practices? | |
| Time of slaughter? | |
| Which season? |
Vaccination Options
| Option | Probability | Expected Utility |
Select Vaccination Decision
Expected Level of Campylobacter at Slaughter
The expected level of campylobacter is logs. The campylobacter level is computed as the weighted average using the middle points of the intervals listed in the table above. The expected value at five weeks is and the expect cost is . This means that the expected profit is .
Cost and Reward System
The model used above implements the following cost and reward system. The reward system is as shown in the table below:
| Logs | |||||
| Gross profit (GBP/chicken) |
The cost function (of the vaccination options) is as shown in the table below:
| Vaccine | ||
| Cost (GBP/chicken) |
References
[Anon, 2010] Anon, 2010. The Joint Government And Industry Target
To Reduce Campylobacter In Uk Produced Chickens By 2015
December 2010. Available online here.
[Crane et al, 2011] Crane, R., Davenport R., and Vaughan, R., 2011. Farm Business Survey 2009/2010. Poultry production in England. Available online here
[EFSA, 2010] Analysis of the baseline survey on the prevalence of Campylobacter in broiler batches
and of Campylobacter and Salmonella on broiler carcasses in the EU, 2008, part A: Campylobacter
and Salmonella prevalence estimates. EFSA Journal 2010; 8(03):1503. Available online here
[Lawes et al, 2012] Investigation of prevalence and risk factors for Campylobacter in broiler flocks at slaughter: results from a UK survey. Centre for Epidemiology and Risk Analysis, Animal Health and Veterinary Laboratories Agency, Surrey, UK. Epidemiol Infect. 2012 May 25:1-13. Lawes JR, Vidal A, Clifton-Hadley FA, Sayers R, Rodgers J, Snow L, Evans SJ, Powell LF. [Epub ahead of print].
[Madsen et al, 2012] An Architecture For Web Deployment Of Decision Support Systems Based On Probabilistic Graphical Models With Applications. Anders L Madsen, Martin Karlsen, Gary C Barker, Anna Garcia, Jeffrey Hoorfar, Frank Jensen, Håkan Vigre. Under Review.