Epidemiological study of Campylobacter spp. colonisation of wild game pheasants (Phasianus colchicus) processed in Approved Game Handling Establishments in Scotland and its relevance to public health

Campylobacteriosis in humans due to Campylobacter jejuni and C. coli is the most common bacterial diarrhoeal disease worldwide. Control measures currently focus on the reduction of Campylobacter in chickens, as 60-80% of human cases can be attributed to the poultry reservoir as a whole. However, C. jejuni and C. coli have also been reported in a range of livestock and wildlife species, including live pheasants. Pheasants reach the consumer’s table as a by-product of the shooting industry. Approximately 3.5 million game birds are shot in Scotland every year; however, only 700,000 (20%) are received at Scottish Approved Game Handling Establishments (AGHEs) for veterinary inspection. Despite this volume of wild game entering the food chain, there is a lack of information concerning the risk of campylobacteriosis in humans arising from consumption of wild game meat and the role wild game birds may have as a reservoir of infection. This study’s aims were to determine the prevalence of Campylobacter in wild game pheasants processed in AGHEs in Scotland, to identify the main sequence types (STs) present and to evaluate their impact on public health. Scotland was divided into five geographical regions. Five sampling sites and 13 estates were selected to collect a total of 287 caecal and 59 skin samples from pheasant carcases during the hunting season 2013/2014. Laboratory isolation of Campylobacter was performed using standard culture methods and positive caecal samples were subjected to PCR and High Throughput Multi Locus Sequence Typing (HiMLST). 36.5% of 287 caecal samples (CI 13.9% - 61.2%) were Campylobacter positive while all 59 skin samples were negative. Using PCR, C. coli and C. jejuni accounted for 62.7% and 37.3% of positive samples tested (n=99), respectively. Nineteen STs of Campylobacter were recovered from MLST (n=80). Sequence type 828 (n=19) was the most common, followed by ST827 (n=12) and ST19 (n=7). Overall, the STs found in pheasants are more common in livestock than chickens, raising the possibility of cross-infection between pheasants, cattle and sheep in the field. STs 827 and 19 are common in humans and primarily associated with livestock, however, ST828 is primarily chicken-associated so this also implies direct involvement of poultry in the transmission of infection to pheasants. This study suggests that wild game birds are a possible source of Campylobacter infection in humans and helps in the understanding of risk to humans of pheasant meat consumption