Michele T Guerin1, Wayne Martin1, Jarle Reiersen2,3, Olaf Berke1,4, Scott A McEwen1, John-Robert Bisaillon5 and Ruff Lowman5
1Department of Population Medicine, Ontario Veterinary College, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
2Reykjagarður hf, Fosshals 1, 112 Reykjavík, Iceland
3Agricultural Agency of Iceland, Austurvegur 64, 800 Selfoss, Iceland
4Department
of Biometry, Epidemiology and Information Processing, University of
Veterinary Medicine Hannover, Bünteweg 2, D-30559 Hannover, Germany
5Canadian Food Inspection Agency, Ottawa, Ontario, K2H 8P9, Canada
Acta Veterinaria Scandinavica 2007,
49:18. This is an Open Access article distributed under the terms of the Creative Commons Attribution License.
Abstract
Background
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 Campylobacter. Our objective in this study was to identify risk factors for flock colonization acting at the broiler farm level.
Methods
Between May 2001 and September 2004, pooled caecal samples were obtained from 1,425 flocks at slaughter and cultured for Campylobacter.
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.
Results
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 Campylobacter 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).
Conclusion
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 Campylobacter,
therefore the use of official water, and potentially, treating
non-official water may reduce the risk of colonization. Manure
management practices deserve further attention.
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