Johanne Ellis-Iversen

Influence of season and geography on Campylobacter jejuni and C. coli subtypes in housed broiler flocks reared in Great Britain.

ABSTRACT Geographical and seasonal variation in the incidence and prevalence of Campylobacter jejuni and C. coli in housed broiler flocks reared in Great Britain in 2004 to 2006 was investigated in this study. Ceca (30) from 797 flocks, not subject to prior partial depopulation and reared on 211 farms, were examined individually for the presence of Campylobacter spp. The best-fitting climatic factors explained approximately 46% of the prevalence of Campylobacter-colonized flocks at slaughter and consisted of a combination of temperature at slaughter, number of sunshine hours in placement month, and millimeters of rainfall in placement month. Positive flocks were more likely to be slaughtered between June and November than during the rest of the year and to be reared in northern Great Britain than in central or southern Great Britain. C. jejuni was identified in approximately 90% of flocks, and C. coli was present in 10% of flocks. The most common clonal complexes identified in 226 isolates typed by multilocus sequence typing (MLST) were ST-45, ST-21, ST-574, ST-443, and ST-828. Flocks slaughtered at the same time were more likely to have similar complexes, and ST-45 had a seasonal pattern, with the highest prevalence in June, and was also more likely to be present in flocks reared in northern Great Britain.

Risk factors for Campylobacter colonisation during rearing of broiler flocks in Great Britain

We investigated the associations between Campylobacter colonisation and management practices and farm characteristics in 603 housed broiler batches originating from 137 farms in Great Britain. All study batches were the initial batch slaughtered from the selected house on enrolled farms. Between 1 and 15 batches were sampled from each farm throughout the study. A total of 34.2% of the batches was Campylobacter positive and multivariable multilevel logistic regression revealed that the risk of Campylobacter colonisation was highest in July (OR=3.4, CI95%:1.8; 6.4), August (OR=3.4, CI95%:1.9; 6.2) and September (OR=3.7, CI95%:1.9; 7.1). Cattle on or adjacent to the farm increased the risk (OR=1.7, CI95%:1.1; 2.7), whereas chlorinated drinking water reduced it (OR=0.5, CI95%:0.2; 0.9). If the first removed batch from the previous flock in the house had been Campylobacter positive, the first batch of the following flock was also more likely to be colonised (OR=3.2, CI95%:2.1; 4.9). This association was more likely due to a persistent risk practice or source of Campylobacter on the farm than a direct carry-over from previous flock.

Flock Health Indicators and Campylobacter spp. in Commercial Housed Broilers Reared in Great Britain

ABSTRACT This study investigated the relationship between flock health and Campylobacter infection of housed commercial broilers in Great Britain. Thirty ceca were collected at slaughter from batches of broilers from 789 flocks, at either full or partial depopulation, between December 2003 and March 2006 and examined individually for Campylobacter by direct plating onto selective media. Management and health data were collected from each flock and included information on mortality or culling during rearing, the number of birds rejected for infectious or noninfectious causes at slaughter, the proportion of birds with digital dermatitis (also termed hock burn), and other general characteristics of the flock. Campylobacter spp. were isolated from 280 (35%) flocks. The relationship between bird health and welfare and Campylobacter status of flocks was assessed using random-effects logistic regression models, adjusting for region, month, year, and rearing regime. Campylobacter-positive batches of ceca were associated with higher levels of rejection due to infection (odds ratio [OR], 1.5; 95% confidence interval [CI95%], 0.98 to 2.30) and digital dermatitis (OR, 2.08; CI95%, 1.20 to 3.61). Furthermore, higher levels of these conditions were also associated with the highest-level category of within-flock Campylobacter prevalence (70 to 100%). These results could indicate that improving health and welfare may also reduce Campylobacter in broilers.

Epidemiology of extended spectrum beta-lactamase E. coli (CTX-M-15) on a commercial dairy farm

The epidemiology of an extended spectrum beta-lactamase Escherichia coli (CTX-M-15) was observed and described on a commercial dairy farm located in the United Kingdom. During 2008 longitudinal sampling of faecal pat samples from different cattle groups comprising milking and non-milking cows, calving cows, calves, and the environment was carried out. The proportion of CTX-M-15 E. coli positive samples was significantly (p<0.0.01) higher in milking cows (30.3%, CI(95%) 26.8; 33.8) than in the herd as a whole (17.0%, CI(95%) 14.9; 19.0). In 2008 95.6% of sampled calves tested positive for CTX-M-15 E. coli at two days of age. A more detailed investigation in 2009 revealed that cows and heifers were approximately eight times more likely to test positive in the 10 days after calving than the 9 days before (OR 7.6, CI(95%) 2.32; 24.9). The CTX-M15 E. coli was also readily isolated from the immediate calving pen environment, including the water troughs. A cyclic pattern was apparent where cows immediately after calving and as high yielders were highly positive, but where the prevalence decreased during the dry period. The increased prevalence of the CTX-M-15 E. coli in certain cattle groups and farm environments including calving pens suggested that husbandry, antimicrobial usage and hygiene may play a significant role on a farm with regards to the epidemiology of CTX-M-15. This may offer a practical opportunity to reduce further dissemination through good practice and hygiene around calving.

Longitudinal Molecular Epidemiological Study of Thermophilic Campylobacters on One Conventional Broiler Chicken Farm

ABSTRACT Improved understanding of the ecology and epidemiology of Campylobacter in the poultry farm environment is key to developing appropriate farm-based strategies for preventing flock colonization. The sources of Campylobacter causing broiler flock colonization were investigated on one poultry farm and its environment, from which samples were obtained on three occasions during each of 15 crop cycles. The farm was adjacent to a dairy farm, with which there was a shared concreted area and secondary entrance. There was considerable variation in the Campylobacter status of flocks at the various sampling times, at median ages of 20, 26, and 35 days, with 3 of the 15 flocks remaining negative at slaughter. Campylobacters were recoverable from various locations around the farm, even while the flock was Campylobacter negative, but the degree of environmental contamination increased substantially once the flock was positive. Molecular typing showed that strains from house surroundings and the dairy farm were similar to those subsequently detected in the flock and that several strains intermittently persisted through multiple crop cycles. The longitudinal nature of the study suggested that bovine fecal Campylobacter strains, initially recovered from the dairy yard, may subsequently colonize poultry. One such strain, despite being repeatedly recovered from the dairy areas, failed to colonize the concomitant flock during later crop cycles. The possibility of host adaptation of this strain was investigated with 16-day-old chickens experimentally exposed to this strain naturally present in, or spiked into, bovine feces. Although the birds became colonized by this infection model, the strain may preferentially infect cattle. The presence of Campylobacter genotypes in the external environment of the poultry farm, prior to their detection in broiler chickens, confirms the horizontal transmission of these bacteria into the flock and highlights the risk from multispecies farms.

Temporal patterns and risk factors for Escherichia coli O157 and Campylobacter spp. in young cattle.

Escherichia coli O157 and Campylobacter jejuni and Campylobacter coli are zoonotic pathogens originating from farm animals. Cattle are the main reservoir for E. coli O157 and also contribute to human cases of campylobacteriosis through contaminated milk, direct contact, and environmental contamination. Thirty groups of young cattle on 30 farms were observed for 7 months and sampled on 4 to 6 separate occasions for E. coli O157 and C. jejuni/coli to characterize shedding patterns and identify risk factors. The within herd prevalence of E. coli O157 per sampling occasion ranged from 0 to 60% (mean = 24%) and average Campylobacter spp. within herd prevalence was 47% ranging from 0 to 100%. The prevalence of E. coli O157-positive herds declined with a linear trend throughout the study from 100 to 38% (OR: 0.5, P < 0.01), whereas time in the study was not significantly associated with Campylobacter prevalence (P = 0.13). Larger herds were more likely to be positive with either or both agents, whereas the number of suckler calves on the farm reduced the risk of both organisms (OR: 0.4/0.6, P < 0.01). Poultry on the premises reduced the risk of E. coli O157, but was not associated with Campylobacter. Emptying and cleaning the water troughs more often than once monthly reduced the risk of detecting Campylobacter and cattle sourced by private water supplies were more likely to be Campylobacter positive. No drinking water management practices were associated with E. coli O157. The risk of detecting both organisms were almost five times higher when the cattle were housed indoors (OR: 4.9, P = 0.03).

Risk factors for Campylobacter jejuni and Campylobacter coli in young cattle on English and Welsh farms

Campylobacter jejuni and C. coli are the most prevalent causes of bacterial diarrhoea in most of the Western World. In Great Britain, the source remains unknown for the majority of cases, though poultry is considered the main source of infection. Molecular typing methods identify cattle as a potential source of a proportion of the non-source-attributed cases, mainly through direct contact, environmental contamination or milk, but little is known about the epidemiology of Campylobacter in cattle. A cross-sectional study was undertaken on young cattle 3-17 months of age on 56 cattle farms in England and Wales to identify association between the presence of C. jejuni and C. coli and farm characteristics and management practices. Campylobacter was detected on 62.5% of the farms and the presence of dairy cows (OR: 3.7, CI(95%): 1.2; 11.7), indoor housing (OR: 4.6, CI(95%): 1.8; 12.0), private water supply (OR: 2.5, CI(95%): 1.2; 5.4), presence of horses (OR: 3.2, CI(95%):1.5; 6.9) and feeding hay (OR: 2.9, CI(95%):1.6; 5.5) were associated with detection. The models goodness-of-fit was improved when herd size was forced in the model without being statistically significant (p=0.34).

Verocytotoxigenic Escherichia coli O157 in animals on public amenity premises in England and Wales, 1997 to 2007

At the request of the public health authorities, 31 public amenity premises in England and Wales containing animals of various species were investigated for the presence of verocytotoxigenic Escherichia coli (VTEC) O157 between 1997 and 2007, because of putative associations with human cases. VTEC O157 was confirmed in one or more species on 19 (61.3 per cent) of the premises. There were significant associations between the presence of VTEC O157 and the number of species sampled, the size of the enterprise, the presence of young cattle and the presence of adult pigs. E coli O157 was isolated from 305 (17.8 per cent) of 1715 samples taken from all the premises, and verocytotoxin genes were detected by PCR in 184 (98.4 per cent) of 187 representative isolates. On positive premises, the highest mean proportion of positive samples (29.0 per cent) was in cattle, followed by sheep (24.4 per cent), donkeys (14.6 per cent), pigs (14.3 per cent), horses (12.3 per cent) and goats (9.9 per cent). A high proportion of positive samples was obtained from camelid species sampled on three of the premises. The main phage types (PT) were 2 and 21/28, which were those most commonly isolated from human cases during the same period. A single PT was detected on 14 of the 19 positive premises, with up to six different species having the same PT.

Risk factors for transmission of foot-and-mouth disease during an outbreak in southern England in 2007

During an outbreak of foot-and-mouth disease (FMD) in southern England in 2007, a case-control study was conducted to identify risk factors for infection and to investigate the relative impact of risk factors on transmission between the infected farms. Seven of the eight case farms in the outbreak and 22 control farms participated. Data were collected via questionnaires and subjected to comparative statistical analysis. Case farms were further classified as primary or secondary according to the likely source of infection during the study. On primary case farms, it was plausible that infection had been introduced directly from the original source. On secondary case farms, FMD infection was more likely to have originated from another infected premises. Calving occurred more frequently on case farms than on control farms during the risk period, and the two primary case farms had a larger proportion of youngstock than the other farms. Secondary case farms (n=5) had a higher composite environmental risk score and a lower biosecurity score than control farms.

Longitudinal study to investigate VTEC O157 shedding patterns in young cattle

Individual animal samples were collected from ten VTEC O157 positive farms approximately monthly over 11months to investigate the shedding of VTEC O157 by youngstock. VTEC O157 was isolated from 7.7% of the 6266 samples and 28.9% of the 1383 animals. On six of the farms VTEC O157 was isolated at multiple visits from several animals, whereas the remaining four farms had one or two positive animals at any one visit, with VTEC isolated from a maximum of four visits. A total of 92 animals were positive more than once (up to four sampling occasions) with a maximum of four negative samples between positive isolations. The results reveal a large variation in individual animal shedding patterns; the proportion of shedding animals on positive farms; and over time within the same farm. The lack of consistent shedding restricts the ability to target potential interventions to specific positive animals/groups or herds.