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Evaluation of best practice recommendations to reduce Campylobacter incidence associated with thinning of broiler flocks.
Project Code: b15020
Veterinary Laboratories Agency, Department of Bacterial Diseases, Veterinary Laboratories Agency
This project was commissioned to evaluate the recommendations made for best practice in a report submitted to the FSA in February 2005 as an output of a previous research project B15004. The previous study examined a very wide range of on-farm procedures and practices associated with catching and thinning operations and showed a clear link between improved hygiene and biosecurity procedures and practices and a reduction in the incidence of Campylobacter. Specific guidance to catching teams and drivers in the form of the industry code of practice was developed majoring on the following priority areas; 1) provision of suitable facilities on farm for changing, washing and meal breaks, 2) provision of suitable and adequate facilities for cleaning and disinfecting vehicles, personnel and footwear, 3) provision of sufficient sets of protective clothing to allow for movement between sites on the same shift.
Originally it was planned to train a nominated catching team and compare the results of microbiological sampling taken during the catching process with those obtained using an untrained team. However, following discussions with the management and staff of the poultry company and recommendations from the FSA and UB statisticians, it was decided that it was preferable for the ADAS team to implement enhanced biosecurity measures under controlled conditions rather than rely on the catching team to follow procedures under potentially difficult circumstances. A protocol was agreed which involved using a mobile messroom to provide facilities for hand washing, changing clothes and boot cleaning and disinfection. This was evaluated in a pilot study before undertaking thirty two farm visits, 16 of which had enhanced biosecurity measures in place and 16 were unenhanced. At each farm visit, records were made describing the process, any enhanced measures undertaken, equipment on site, the catching teams involved and the weather conditions. The number of samples taken for microbiological examination was increased following the pilot study to include crates, modules and the main drive. Faecal samples were also examined from the ‘target’ house, (the first house to be thinned) and adjoining houses to ensure that flocks were not already colonised on the farm.
These studies confirm previous findings in FSA project B15004 and demonstrate that contaminated equipment, vehicles and personnel entering the broiler farm environment and houses during thinning present a risk for infection of the remaining birds with Campylobacter. In this exercise, fifteen target flocks which were negative at thin became infected by the time the houses were cleared of birds despite seven of these having been subjected to enhanced hygiene and biosecurity measures during the thinning process.
Although there were substantial reductions in Enterobacteriaceae numbers and the incidence of Campylobacter on vehicles and catcher’s hands and shoes with these measures, campylobacters were still isolated from these sources on many occasions. Moreover, evidence from the molecular typing demonstrated close similarity between isolates from dirty and cleaned footwear and subsequent isolates found in one of the flocks indicating the difficulty of effectively removing the organism from this type of footwear. There were clear associations between isolates recovered from the outside or inside of the messroom taken following cleaning procedures and strains subsequently colonizing flocks on another farm visit. Such isolates are likely to have been washed off from personnel and footwear during the enhanced biosecurity procedures, indicating that cleaning was at least partially effective in removal of campylobacters. These findings lend weight to the importance of cleanliness of personnel entering the house at thin.
Over a third of catcher’s vehicles, and live bird transport lorries including the steps, were already contaminated with campylobacters before entering the farm and the former proved especially difficult to successfully clean in order to remove the organism. Isolates from vehicles on seven of the farm visits were indistinguishable from the subsequent flock colonizing strain. Campylobacter was isolated from over two-thirds of crates or modules entering the farm and were contaminated on more than 85% of the farm visits while isolates from these sources were indistinguishable to those subsequently colonizing the flock on nine of the fifteen farms studied. The potential risk for strain transmission via personnel and equipment moving between different farms was confirmed by common genotypes isolated from crates, catcher’s shoes, the cleaning unit and flocks on several farms. Given the difficulty of successfully reducing microbial numbers and logistical and time limitations on the farm before the process it may prove more effective to clean and sanitise the vehicles and footwear elsewhere.
It is disappointing that this study cannot provide evidence of the effectiveness of recommendations to reduce the risk associated with thinning but it has reconfirmed the problem areas and has demonstrated the difficulties in cleaning vehicles, footwear and even hands of personnel involved in the process.
Following the completion of the project, an Impact Assessment (IA) was undertaken to examine the costs to the industry of implementing enhanced hygiene and biosecurity measures in relation to the wider benefits to consumers and other interested stakeholders. Given the lack of clear evidence that the enhanced procedures reduced the incidence of Campylobacter, and mindful of the high costs of implementing and operating to the standards adopted during the project, the recommended option was that hygiene practices for broiler thinning should continue in line with current guidance. The impact assessment also proposed that no government action (e.g. active promotion of additional measures) was warranted. The FSA intend to review the findings of the Impact Assessment in 2011 in the light of any new evidence that may become available.
The project identified a number of areas where further work might be warranted. These are:
1) To investigate best practice and methods for cleaning and disinfecting vehicles
2) To investigate best practice or design of footwear for cleaning and disinfection purposes
3) To investigate additional interventions prior and post thinning e.g. organic acids in water.
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