Quantification of Salmonella and Yersinia on pork carcasses by simulation modelling

Stagnation in the success of control programmes in pig production in Denmark has led to an increased interest in the development of alternative control strategies such as decontamination of carcasses to further decrease the attribution of pork meat to human foodborne illness. This project sets out to develop a model for quantitative estimation of slaughterhouse output of Salmonella and Yersinia . Distributions of the occurrence of Salmonefla, Yersinia and E. coli on pork carcasses are based on the analysis of paired faecal samples and carcass swabs from 2880 animals originating from four abattoirs. By combining the estimated quantity of faecal contamination of carcasses with a semi-quantitative distribution of the number of Safmoneffa or Yersinia per gram faeces, an output distribution describing the number of Salmonella or Yersinia bacteria per carcass can be established. In order to validate the model, carcass swabs, analysed for Salmonefla and Yersinia serve as control. After the model has been validated, the effect of various decontamination methods on human exposure to foodborne pathogens in pork will be evaluated in both economic terms as well as with regard to public health impact

Isolation of Salmonella enterica in seropositive classified finishing pig herds

The aim of this study was to assess the probability of detecting Salmonella from pen faecal samples in seropositive classified finishing pig herds. The study involved 77 herds from Denmark (20), the Netherlands (20), Greece (17) and Germany (20). The serological herd status was determined by the blood- sampling of 50 finishing pigs. Bacteriological sampling was performed by 20 pen faecal samples per herd. Over-all, 47 % of the blood samples had an OD% larger than 10 and 23 % larger than 40. Salmonella was isolated from 135 (9.3 %) pen faecal samples in 32 herds (42 %). Twenty-eight of these herds (87.5 %) had a within-herd seroprevalence larger than 50% at sample cut-off OD%\u3e10. A correlation coefficient of 0.62 was found between the proportion of culture positive- and seropositive samples in a herd at cut-off OD % \u3e 10 and of 0.58 at cut-off OD % \u3e 40. Due to the low sensitivity of culture methods, apparent ‘false positive’ serological results may well represent real infections not detected by bacteriological testing. In this study, there was an increasing probability of recovering Salmonella with increasing within-herd seroprevalence

Eliciting expert knowledge on Salmonella enterica dynamics in swine at the pre-harvest level

A workshop was conducted to elicit expert knowledge on infection status and transmission of salmonella in pigs at the farm of origin, during transport and during lairage. Thirty-six experts from II countries filled in a paper-and-pencil questionnaire during an international conference. The group of US and Danish experts were large enough to be analysed separately. The results indicated that experts from all countries agreed on the risk of salmonella introduction related to live animals and the significance of general hygiene and all-in/all-out management for salmonella control. However, workshop participants from Denmark put more weight on factors related to feed while experts from the USA rated factors related to rodents and people contact higher. The experts believed that 1/3 of the infected pigs from a chronically infected farm would be shedders. There were differences in risk perception between experts from Denmark and the USA regarding contamination during Jairage and transport as well as regarding incidence of salmonella shedding during transport and Jairage. In conclusion, the results reflect the differences in the level of salmonella infection and control between countries. The study does not allow differentiation between true differences in salmonella dynamics between countries or differences in perception only

Salmonella Serovars from Humans and Other Sources in Thailand, 1993–2002

We serotyped 44,087 Salmonella isolates from humans and 26,148 from other sources from 1993 through 2002. The most common serovar causing human salmonellosis in Thailand was Salmonella enterica Weltevreden. Serovars causing human infections in Thailand differ from those in other countries and seem to be related to Salmonella serovars in different food products and reservoirs

A European longitudinal study in Salmonella seronegative-and seropositive classified finishing pig herds

A study was performed to assess the stability of an assigned Salmonella status of finishing pig herds over time, seasonal variation in the incidence of herd infections, the herd incidence of Salmonella infections from the grower to the finisher production stage and the correlation between serological and bacteriological herd classification