The study aimed to identify sources of campylobacter in 10 housed broiler flocks from three United Kingdom poultry companies. Samples from (i) the breeder flocks, which supplied the broilers, (ii) cleaned and disinfected houses prior to chick placement, (iii) the chickens, and (iv) the environments inside and outside the broiler houses during rearing were examined. Samples were collected at frequent intervals and examined for Campylobacter spp. Characterization of the isolates using multilocus sequence typing (MLST), serotyping, phage typing, and flaA restriction fragment length polymorphism typing was performed. Seven flocks became colonized during the growing period. Campylobacter spp. were detected in the environment surrounding the broiler house, prior to as well as during flock colonization, for six of these flocks. On two occasions, isolates detected in a puddle just prior to the birds being placed were indistinguishable from those colonizing the birds. Once flocks were colonized, indistinguishable strains of campylobacter were found in the feed and water and in the air of the broiler house. Campylobacter spp. were also detected in the air up to 30 m downstream of the broiler house, which raises the issue of the role of airborne transmission in the spread of campylobacter. At any time during rearing, broiler flocks were colonized by only one or two types determined by MLST but these changed, with some strains superseding others. In conclusion, the study provided strong evidence for the environment as a source of campylobacters colonizing housed broiler flocks. It also demonstrated colonization by successive campylobacter types determined by MLST during the life of a flock.

The recent development of simple, rapid genotyping techniques for Campylobacter species has enabled investigation of the determinative epidemiology of these organisms in a variety of situations. In this study we have used the technique of fla typing (PCR-restriction fragment length polymorphism analysis of the flaA and flaB genes) to identify the sources of strains contaminating the carcasses of five campylobacter-positive and two campylobacter-negative broiler flocks during abattoir processing. The results confirmed that, in the United Kingdom, individual broiler flocks are colonized by a limited number of subtypes of Campylobacter jejuni or C. coli. In some but not all cases, the same subtypes, isolated from the ceca, contaminated the end product as observed in carcass washes. However, the culture methodology, i.e, use of direct plating or enrichment, affected this subtype distribution. Moreover, the number of isolates analyzed per sample was limited. fla typing also indicated that some campylobacter subtypes survive poultry processing better than others. The extent of resistance to the environmental stresses during processing varied between strains. The more robust subtypes appeared to contaminate the abattoir environment, surviving through carcass chilling, and even carrying over onto subsequent flocks. From these studies it is confirmed that some campylobacter-negative flocks reach the abattoir but the carcasses from such flocks are rapidly contaminated by various campylobacter subtypes during processing. However, only some of these contaminating subtypes appeared to survive processing. The sources of this contamination are not clear, but in both negative flocks, campylobacters of the same subtypes as those recovered from the carcasses were isolated from the crates used to transport the birds. In one case, this crate contamination was shown to be present before the birds were loaded.

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Campylobacter spp., especially Campylobacter jejuni and C. coli, are the main cause of human bacterial gastroenteritis in the developed world (http://www.who.int/mediacentre /factsheets/fs255/en/). Chicken meat is frequently contaminated with Campylobacter (19), and it is a commonly held view that reducing the number of flocks infected with this organism would reduce the number of human Campylobacter cases. A better understanding of the epidemiology of Campylobacter in broiler flocks is required in order to design successful control programs at the farm level.In some European countries, flock colonization of chickens with Campylobacter has a clear seasonal pattern, with highest rates seen in the summer or autumn (20). Studies in the United Kingdom in the early 1990s suggested that there was no increase in the proportion of flocks colonized with campylobacters in warmer months (21, 28). However, we recently found that housed flocks were more likely to be Campylobacter positive in summer (46) in a geographical subset of the data in this study, and evidence of seasonality was also found in 401 batches reared in the United Kingdom in 2008 (20). The reasons for the seasonal variation are not fully understood but are likely to involve the frequency and nature of exposure of the flocks to Campylobacter spp. There is further evidence that climatic factors such as temperature correlate with both broiler flock and human infections (36,43,52). Temperature could also affect the environmental sources of Campylobacter spp. to which broiler chickens may become exposed. A better understanding of the roles of season and climatic factors and their relative impacts on broiler flock colonization with Campylobacter will be useful for policy makers and broiler companies who are formulating control programs to reduce flock infection with this important zoonotic pathogen.Typing of isolates from foods and clinical cases has provided evidence that many strains isolated from chickens share attributes with those from human cases (13,25,37). Multilocus sequence typing (MLST) has been used to assess the relative importance of sources, reservoirs, and transmission routes for human Campylobacter infection in the United Kingdom (48,56). The population of Campylobacter isolates from human cases in England has been well analyzed by studies of isolates from Ͼ2,900 cases from three areas spanning the years 2000 to 2006 (14, 56). However, data sets for strains from chicken flocks at slaughter were smaller and may have been less representative. For example, while 307 chicken isolates were cited

Wild mice and voles were tested for Cryptosporidium during a 2-year survey at an agricultural site in Warwickshire, United Kingdom. C. parvum and C. muris, the two cryptosporidial species known to infect mammals, were detected. Prevalence figures of 22%, 21% and 13% noted for C. parvum for Mus domesticus, Apodemus sylvaticus and Clethrionomys glareolus, respectively, were higher than those recorded for C. muris at 10%, 6% and 2%. C. parvum causes the sometimes severe diarrhoeal disease cryptosporidiosis in many hosts, but the wild rodents were asymptomatic. The discovery of C. muris in A. sylvaticus and C. glareolus confirms a wider distribution in wild rodents than has previously been reported. Rodents may represent a significant reservoir of Cryptosporidium with a high potential for infection of man and livestock due to cohabitation.