House-level risk factors associated with the colonization of broiler flocks with Campylobacter spp. in Iceland, 2001 – 2004

<p>Abstract</p> <p>Background</p> <p>The concurrent rise in consumption of fresh chicken meat and human campylobacteriosis in the late 1990's in Iceland led to a longitudinal study of the poultry industry to identify the means to decrease the frequency of broiler flock colonization with <it>Campylobacter</it>. Because horizontal transmission from the environment is thought to be the most likely source of <it>Campylobacter </it>to broilers, we aimed to identify broiler house characteristics and management practices associated with flock colonization. Between May 2001 and September 2004, pooled caecal samples were obtained from 1,425 flocks at slaughter and cultured for <it>Campylobacter</it>. Due to the strong seasonal variation in flock prevalence, analyses were restricted to a subset of 792 flocks raised during the four summer seasons. Logistic regression models with a farm random effect were used to analyse the association between flock <it>Campylobacter </it>status and house-level risk factors. A two-stage process was carried out. Variables were initially screened within major subsets: ventilation; roof and floor drainage; building quality, materials and repair; house structure; pest proofing; biosecurity; sanitation; and house size. Variables with p ≤ 0.15 were then offered to a comprehensive model. Multivariable analyses were used in both the screening stage (i.e. within each subset) and in the comprehensive model.</p> <p>Results</p> <p>217 out of 792 flocks (27.4%) tested positive. Four significant risk factors were identified. <it>Campylobacter </it>colonization was predicted to increase when the flock was raised in a house with vertical (OR = 2.7), or vertical and horizontal (OR = 3.2) ventilation shafts, when the producer's boots were cleaned and disinfected prior to entering the broiler house (OR = 2.2), and when the house was cleaned with geothermal water (OR = 3.3).</p> <p>Conclusion</p> <p>The increased risk associated with vertical ventilation shafts might be related to the height of the vents and the potential for vectors such as flies to gain access to the house, or, increased difficulty in accessing the vents for proper cleaning and disinfection. For newly constructed houses, horizontal ventilation systems could be considered. Boot dipping procedures should be examined on farms experiencing a high prevalence of <it>Campylobacter</it>. Although it remains unclear how geothermal water increases risk, further research is warranted to determine if it is a surrogate for environmental pressures or the microclimate of the farm and surrounding region.</p

A farm-level study of risk factors associated with the colonization of broiler flocks with Campylobacter spp. in Iceland, 2001 – 2004

<p>Abstract</p> <p>Background</p> <p>Following increased rates of human campylobacteriosis in the late 1990's, and their apparent association with increased consumption of fresh chicken meat, a longitudinal study was conducted in Iceland to identify the means to decrease the frequency of broiler flock colonization with <it>Campylobacter</it>. Our objective in this study was to identify risk factors for flock colonization acting at the broiler farm level.</p> <p>Methods</p> <p>Between May 2001 and September 2004, pooled caecal samples were obtained from 1,425 flocks at slaughter and cultured for <it>Campylobacter</it>. Due to the strong seasonal variation in flock prevalence, analyses were restricted to a subset of 792 flocks raised during the four summer seasons. Flock results were collapsed to the farm level, such that the number of positive flocks and the total number of flocks raised were summed for each farm. Logistic regression models were fitted to the data using automated and manual selection methods. Variables of interest included manure management, water source and treatment, other poultry/livestock on farm, and farm size and management.</p> <p>Results</p> <p>The 792 flocks raised during the summer seasons originated from 83 houses on 33 farms, and of these, 217 (27.4%) tested positive. The median number of flocks per farm was 14, and the median number of positive flocks per farm was three. Three farms did not have any positive flocks. In general, factors associated with an increased risk of <it>Campylobacter </it>were increasing median flock size on the farm (p ≤ 0.001), spreading manure on the farm (p = 0.004 to 0.035), and increasing the number of broiler houses on the farm (p = 0.008 to 0.038). Protective factors included the use of official (municipal) (p = 0.004 to 0.051) or official treated (p = 0.006 to 0.032) water compared to the use of non-official untreated water, storing manure on the farm (p = 0.025 to 0.029), and the presence of other domestic livestock on the farm (p = 0.004 to 0.028).</p> <p>Conclusion</p> <p>Limiting the average flock size, and limiting the number of houses built on new farms, are interventions that require investigation. Water may play a role in the transmission of <it>Campylobacter</it>, therefore the use of official water, and potentially, treating non-official water may reduce the risk of colonization. Manure management practices deserve further attention.</p

Comparison of sensitivity of Campy-Cefex dilution method and PCR in detecting Campylobacter in broilers

The aim of the study was to compare the sensitivity of a Campy-Cefex dilution method and PCR for detecting Campylobacter in broilers and to see if any traces of the bacteria were to be found by these methods during winter when the bacteria is not detectable by conventional microbiological methods. The results of our studies done in 2004 and 2005 were compared with data from 2001-2003 soon after a national surveillance of Campylobacter spp. in broilers was initiated. Faecal samples from 607 broiler flocks were pooled, 10 samples per pool, and diluted in saline for the Campy-Cefex direct plating dilution method and PCR. The PCR amplification was performed in a Peltier Thermal Cycler and the primers used were C412F and C1288R. A total of 742 pooled caecal samples were collected at slaughter. Samples from each pool of 40 caeca were diluted in saline for the Campy-Cefex direct plating dilution method. The PCR method proved to be more sensitive than the Campy-Cefex method but still did not detect any traces of Campylobacter during winter. A comparison of the results from 2001-2003 with the results from 2004-2005 indicates that the percentage of positive flocks had diminished. The study underlines the importance of using sensitive methods for detecting Campylobacter spp. in order to minimize the risk of human exposure. The finding that the sensitive PCR method was not able to detect Campylobacter during winter suggests that the seasonal pattern of campylobacteriosis is due to a new vector in the spring which carries the bacterium.Samanburður á næmi tveggja aðferða við greiningu á Campylobacter í kjúklingum, Campy-Cefex ræktunaraðferðar með raðþynningum og PCR aðferðar. Tilgangur rannsóknarinnar var að bera saman næmi tveggja aðferða við greiningu Campylobacter, Campy-Cefex ræktunaraðferðar með raðþynningum og PCR aðferðar. Þessar aðferðir voru notaðar við greiningu á bakteríunni úr kjúklingasýnum yfir vetur þegar lítið smit greinist með hefðbundnum ræktunaraðferðum. Niðurstöður rannsóknarinnar sem stóð yfir frá árinu 2004 til ársins 2005 eru bornar saman við upplýsingar frá árinu 2000 þegar farið var út í fyrirbyggjandi aðgerðir gegn Campylobacter smiti í kjúklingaeldi. Ræktað var úr 607 safnsýnum frá kjúklingum í eldi, 10 saursýni saman í sýni. Gerð var þynning á sýnunum í saltvatni og þeim sáð í raðþynningum út á skálar með Campy-Cefex agar. Sömu sýni voru mögnuð upp með C412F og C1288R vísum í „Peltier Thermal Cycler“ PCR tæki. Ræktað var úr 742 safnsýnum frá kjúklingum úr slátrun, 40 botnlangasýni saman. Sýnin voru raðþynnt í saltvatni og þeim sáð út á skálar með Campy-Cefex agar. PCR aðferðin reyndist næmari en Campy-Cefex aðferðin en hún greindi þó ekki nein merki um Campylobacter í kjúklingasýnum yfir vetrarmánuðina. Samanburður niðurstaðna við stöðuna í kjúklingaeldi árin 2001-2003 bendir til þess að hlutfall Campylobacter jákvæðra kjúklingahópa hefur minnkað á tímabilinu. Niðurstöður rannsóknarinnar undirstrika mikilvægi þess að nota næmar aðferðir við greiningu á Campylobacter til að lágmarka hættu á smiti í fólk. PCR aðferðin greindi ekki Campylobacter að vetri til og bendi það til þess að hin ársbundna sveifla í Campylobacter eigi rætur sínar að rekja til nýsmits að vori

Lack of Evidence for Vertical Transmission of Campylobacter spp. in Chickens

Campylobacter jejuni is a major cause of bacterial food-borne infection in the industrial world. There is evidence that C. jejuni is present in eggs and hatchery fluff, opening the possibility for vertical transmission from hens to progeny. Poultry operations in Iceland provide an excellent opportunity to study this possibility, since breeding flocks are established solely from eggs imported from grandparent flocks in Sweden. This leaves limited opportunity for grandparents and their progeny to share isolates through horizontal transmission. While Campylobacter was not detected in all grandparent flocks, 13 of the 16 egg import lots consisted of eggs gathered from one or more Campylobacter-positive grandparent flocks. No evidence of Campylobacter was found by PCR in any of the 10 relevant quarantine hatchery fluff samples examined, and no Campylobacter was isolated from the parent birds through 8 weeks, while they were still in quarantine rearing facilities. After the birds were moved to less biosecure rearing facilities, Campylobacter was isolated, and 29 alleles were observed among the 224 isolates studied. While three alleles were found in both Sweden and Iceland, in no case was the same allele found both in a particular grandparent flock and in its progeny. We could find no evidence for vertical transmission of Campylobacter to the approximately 60,000 progeny parent breeders that were hatched from eggs coming from Campylobacter-positive grandparent flocks. If vertical transmission is occurring, it is not a significant source for the contamination of chicken flocks with Campylobacter spp

Broiler Campylobacter Contamination and Human Campylobacteriosis in Iceland ▿ †

To examine whether there is a relationship between the degree of Campylobacter contamination observed in product lots of retail Icelandic broiler chicken carcasses and the incidence of human disease, 1,617 isolates from 327 individual product lots were genetically matched (using the flaA short variable region [SVR[) to 289 isolates from cases of human campylobacteriosis whose onset was within approximately 2 weeks from the date of processing. When there was genetic identity between broiler isolates and human isolates within the appropriate time frame, a retail product lot was classified as implicated in human disease. According to the results of this analysis, there were multiple clusters of human disease linked to the same process lot or lots. Implicated and nonimplicated retail product lots were compared for four lot descriptors: lot size, prevalence, mean contamination, and maximum contamination (as characterized by direct rinse plating). For retail product distributed fresh, Mann-Whitney U tests showed that implicated product lots had significantly (P = 0.0055) higher mean contamination than nonimplicated lots. The corresponding median values were 3.56 log CFU/carcass for implicated lots and 2.72 log CFU/carcass for nonimplicated lots. For frozen retail product, implicated lots were significantly (P = 0.0281) larger than nonimplicated lots. When the time frame was removed, retail product lots containing Campylobacter flaA SVR genotypes also seen in human disease had significantly higher mean and maximum contamination numbers than lots containing no genotypes seen in human disease for both fresh and frozen product. Our results suggest that cases of broiler-borne campylobacteriosis may occur in clusters and that the differences in mean contamination levels may provide a basis for regulatory action that is more specific than a presence-absence standard