(LINKED TO PX004 RGA1535) INTEGRATING MICROBIOLOGY AND MODELLING TO DETERMINE THE SOURCE OF CAMPYLOBACTER INFECTION IN THE BROILER HOUSE AND DEVELOP INTERVENTIONS.

Integrating microbiology and modelling to determine the source of Campylobacter infection in the broiler house and develop interventions

Campylobacter is the largest cause of recognised bacterial gastroenteritis in the developed world. The 2009 reporting rates for Great Britain show more than 64 000 cases, an increase of 30% in Scotland and 14% in England & Wales on the previous year, that has continued into 2010. Because there is substantial under-reporting of campylobacteriosis, the actual number of cases in 2009 is likely to be closer to 450 000. Further, about 10% of reported cases are hospitalised. This rise is all the more disappointing because rates of infection with Campylobacter had been falling between 2000 and 2005. Molecular strain typing, by us and others, has identified that poultry is significantly the most important source of this infection with the most common types found in human beings also being the most common in chickens. Studies on retail poultry show a prevalence of Campylobacter in this meat of over 65% with the main routes of infection being eating improperly cooked meat or cross-contamination to uncooked foods. To reduce this burden of human disease, action must be taken to reduce Campylobacter loads in poultry and The Food Standards Agency, Defra and BBSRC have all identified this as a major priority. The FSA is considering targets for the reduction in levels of Campylobacter in raw chicken at retail, to be achieved by April 2015. The target will be set and achieved through stakeholder engagement and partnership working. Interventions in the poultry industry abroad have resulted in dramatic decreases in human infection rates. For example, in Iceland where freezing of positive carcasses is used, in New Zealand where interventions and regulations were introduced and in the USA where improved hygiene and the use of chlorine washes for carcasses has been implemented. However, UK industry has largely been unable to achieve reductions. Although strategies such as poultry vaccination are attractive in the longer term, more immediately it will be through informed biosecurity interventions on broiler farms that control is likely to be most readily achieved. Indeed UK producers widely recognise that where robust biosecurity remains unbreached, as for the valuable (grand)parent birds that are used to produce the eggs that hatch into broilers, then Campylobacter colonisation is uncommon. It is in the high throughput broiler production that colonisation regularly occurs and where novel biosecurity controls, as proposed here, could play an important role. Our previous studies of the sources of Campylobacter infection in humans not only identified the principal source as broiler chickens, it also identified that the distribution of Campylobacter strains found in humans and in the reservoirs of chicken, cattle, sheep, wild birds, pigs etc, were quite distinct with some strains common to several hosts. This proposal seeks to better understand the relative importance of the potential sources of Campylobacter in broilers by using a modelling approach. The hypothesis is that some Campylobacter strains and some Campylobacter reservoirs are much more important than others in this process and that it is only by quantitating their relative importance and their interaction with each other that it will be possible to robustly identify the sources of Campylobacter in the broiler house and hence introduce effective measures to prevent the colonisation of these birds during production. The findings will enable policy to be developed (e.g. code of practice) to define which control measures are most effective in keeping broiler houses Campylobacter free. This will strongly influence industry through improved farming practice.