Year: 2014
Type: dissertation
Abstract: Yersinia enterocolitica is a foodborne zoonotic pathogen. Among domestic animals, pigs are considered the major reservoir of Y. enterocolitica bioserotype 4/O:3. The pathogen is found in pig carcasses and pluck sets at slaughterhouses. Carcass contamination at the slaughterhouse originates from pigs that are already infected on farms. Considerable variation exists in the prevalence of Y. enterocolitica between different pig farms. The aim of this study was to determine the factors in farm management that can be used to prevent the presence and spread of this pathogen within and between farms. Multiple-locus variable-number tandem repeat analysis (MLVA) has been developed and used for genotyping of Y. enterocolitica strains of human origin. This genotyping method was used here to investigate its discriminatory ability, advantages and limitations, and use in genotyping Y. enterocolitica strains isolated from pigs. Among Y. enterocolitica 4/O:3 strains that originated from humans, pigs, and pork products from four European countries, the use of MLVA was found to have high discriminatory power. Similar MLVA types were detected among humans and pigs, human clinical isolates from limited geographical locations indicating the presence of past unidentified epidemics and also from pigs that originated from the same farms. MLVA proved to be able to detect farm-specific genotypes, but mild variation was common in strains originating from the same farms. Sampling of the farms revealed the spread of similar MLVA types among farms that had previously transported pigs between each other. Pigs were found to be a major source of transmission of this pathogen between all production types, including farrowing, farrow-to-finish, and fattening farms. Piglets from certain breeding farms served as a major source of infection for fattening pigs. These piglets carried farrowing farm-specific MLVA types of Y. enterocolitica to the fattening farm, and the infection spread throughout the fattening unit. Farm management practices and their association with carriage and shedding of Y. enterocolitica in pigs were studied by a purpose-designed questionnaire for farms whose pigs were previously sampled at slaughterhouses. The use of municipal water, organic production, and purchase of feed from a certain feed company were found to be protective factors against the carriage of Y. enterocolitica. In contrast, snout-to-snout contacts between pens and buying feed from another company were discovered as risk factors for fecal shedding of the pathogen. In total, 30 farms were further visited and sampled for enteropathogenic Yersinia, and the management practices and conditions were recorded during each sampling visit. The use of municipal water, the use of an all-in all-out system in the units of weaned piglets and fattening pigs, buying piglets from no more than one supplier at a time, and generous use of bedding were associated with lower prevalence of Y. enterocolitica on farms.
Source: Työväentutkimus Vuosikirja
Author: Sonja Virtanen
Language: English
Subfield: Infectious Diseases
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W2113201059