Feed-borne Outbreak of Salmonella Cubana in Swedish Pig Farms: Risk Factors and Factors Affecting the Restriction Period in Infected Farms

In 2003, a feed-borne outbreak of Salmonella Cubana occurred in Sweden as a result of contamination in a feed plant. Salmonella Cubana was detected in 49 out of 77 pig farms having received possibly contaminated feed. In this study, potential risk factors for farms being salmonella positive were examined, and a survival analysis was performed to investigate risk factors affecting the restriction period for salmonella positive farms. The median restriction time for all 49 farms was 17 weeks. An increased risk for farms being salmonella infected (positive in feed and/or faeces) was seen for fattening farms and farms feeding soy. The survival analysis showed that herds with a low level of infection and farms with a high hygiene level had shorter restriction times. This study is unique as it investigates a real outbreak of feed-borne salmonella, where the source of infection was reliably identified, the period of exposure could be defined and data were collected from all exposed farms

Assessment of control measures against livestock-associated methicillin-resistant Staphylococcus aureus in a farrow-to-finish pig herd using infectious disease modelling

Pigs are considered to be the main reservoir for livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA), which is a zoonotic opportunistic pathogen. As LA-MRSA is an occupational hazard, there is an incentive to control its spread in pig herds. Currently, knowledge about effective control measures which do not require culling the whole herd are limited, and the control strategies against LA-MRSA vary between countries. This study uses a stochastic compartment model to simulate possible control measures for LA-MRSA in a farrow-to-finish pig herd. The aims of the study were to (1) extend a previously published disease spread model with additional management and control measures; (2) use the extended model to study the effect of the individual LA-MRSA control measures on the within-herd LA-MRSA prevalence; (3) evaluate the effect of control measures when they are implemented in combinations. From the individual control measures tested in the study, thorough cleaning was found to be most effective in reducing the LA-MRSA prevalence in the herd. When the different control measures were combined, cleaning together with disease surveillance had the largest impact on reducing the LA-MRSA and a higher chance of causing disease elimination. The results of the study showed that achieving disease elimination once LA-MRSA had been introduced in the herd was challenging but was more likely when control measures were introduced early during the outbreak. This emphasises the importance of early detection of the pathogen and subsequent rapid implementation of LA-MRSA control measures.(c) 2023 The Author(s). Published by Elsevier B.V. on behalf of The Animal Consortium. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)

Geographical distribution of salmonella infected pig, cattle and sheep herds in Sweden 1993-2010

<p>Abstract</p> <p>Background</p> <p>The Swedish salmonella control programme covers the entire production chain, from feed to food. All salmonella serotypes are notifiable. On average, less than 20 cases of salmonella in food-producing animals are reported every year. In some situations, the cases would be expected to cluster geographically. The aim of this study was to illustrate the geographic distribution of the salmonella cases detected in pigs, cattle and sheep.</p> <p>Methods</p> <p>Data on all herds with pigs, cattle and sheep found to be infected with salmonella during the time period from 1993 to 2010 were obtained from the Swedish Board of Agriculture. Using the ArcGIS software, various maps were produced of infected herds, stratified on animal species as well as salmonella serotype. Based on ocular inspection of all maps, some were collapsed and some used separately. Data were also examined for temporal trends.</p> <p>Results</p> <p>No geographical clustering was observed for ovine or porcine cases. Cattle herds infected with Salmonella Dublin were mainly located in the southeast region and cattle herds infected with Salmonella Typhimurium in the most southern part of the country. Some seasonal variation was seen in cattle, but available data was not sufficient for further analyses.</p> <p>Conclusions</p> <p>Analyses of data on salmonella infected herds revealed some spatial and temporal patterns for salmonella in cattle. However, despite using 18 years' of data, the number of infected herds was too low for any useful statistical analyses.</p

Water quality modelling: microbial risks associated with manure on pasture and arable land

While agricultural activities, such as the application of manure on arable land and animal grazing on pastures, provide economic and environmental benefits, they may also pose microbial risks to water sources. The aim of this paper was to study the microbial fate and transport in an agricultural catchment and recipient water source through further development of the hydrological model HYPE. Hydrological modelling was combined with hydrodynamic modelling to simulate the fate and transport of Salmonella spp., verotoxin-producing Escherichia coli O157:H7 and Cryptosporidium parvum in an agricultural catchment of a drinking water source, Lake Vombsj\uf6n, in Sweden. This approach was useful to study the influence of different processes on the pathogen fate and transport, and to interpret the relative changes in the simulated concentrations. Sensitivity analysis indicated that the largest uncertainties in the model were associated with the estimation of pathogen loads, parameterisation of the pathogen processes, and simulation of partitioning between surface runoff and infiltration. The proposed modelling approach is valuable for assessing the relative effect of different risk-reducing interventions

Effects of a participatory approach, with systematic impact matrix analysis in herd health planning in organic dairy cattle herds

The animal health and welfare status in European organic dairy production does not in all aspects meet the organic principles and consumers’ expectations and needs to be improved. To achieve this, tailored herd health planning, targeted to the specific situation of individual farms could be of use. The aim of this study was to apply herd health planning in a structured participatory approach, with impact matrix analysis, not previously used in this context, in European organic dairy farms and to assess changes in animal health and welfare. Herd health planning farm visits were conducted on 122 organic dairy farms in France, Germany and Sweden. The farmer, the herd veterinarian and/or an advisor took part in the farm discussions. The researcher served as facilitator. Baseline data on the animal health status of the individual farm, collected from national milk recording schemes, were presented as an input for the discussion. Thereafter a systematic impact matrix analysis was performed. This was to capture the complexity of individual farms with the aim to identify the farm-specific factors that could have a strong impact on animal health. The participants (i.e. farmer, veterinarian and advisor) jointly identified areas in need of improvement, taking the health status and the interconnected farm system components into account, and appropriate actions were jointly identified. The researcher took minutes during the discussions, and these were shared with the participants. No intervention was made by the researcher, and further actions were left with the participants. The number of actions per farm ranged from 0 to 22. The change in mortality, metabolic diseases, reproductive performance and udder health was assessed at two time points, and potential determinators of the change were evaluated with linear regression models. A significant association was seen between change in udder health, as measured by the somatic cell count, and country. At the first follow-up, a significant association was also found between change in the proportion of prolonged calving interval and the farmers’ desire to improve reproductive health as well as with an increase in herd size, but this was not seen at the second follow-up. The degree of implementation of the actions was good (median 67%, lower quartile 40%, upper quartile 83%). To conclude, the degree of implementation was quite high, improvement of animal health could not be linked to the herd health planning approach. However, the approach was highly appreciated by the participants and deserves further study.info:eu-repo/semantics/acceptedVersio

Detection and identification by PCR of Clostridium chauvoei in clinical isolates, bovine faeces and substrates from biogas plant

<p>Abstract</p> <p>Background</p> <p><it>Clostridium chauvoei </it>causes blackleg, an acute disease associated with high mortality in ruminants. The apparent primary port of entry is oral, during grazing on pasture contaminated by spores. Cases of blackleg can occur year after year on contaminated pastures. A method to determine the prevalence of <it>C. chauvoei </it>spores on pasture would be useful.</p> <p>The standard method for <it>C. chauvoei </it>detection is culture and biochemical identification, which requires a pure culture. In most muscle samples from cattle dead from blackleg the amount of <it>C. chauvoei </it>in samples is high and the bacterium can easily be cultured, although some samples may be contaminated. Detection by PCR would be faster and independent of contaminating flora.</p> <p>Digested residues from biogas plants provide an excellent fertiliser, but it is known that spore-forming baeria such as <it>Clostridium </it>spp. are not reduced by pasteurisation. The use of digested residues as fertiliser may contribute to the spread of <it>C. chauvoei</it>. Soil, manure and substrate from biogas plants are contaminated with other anaerobic bacteria which outgrow <it>C. chauvoei</it>. Therefore, detection by PCR is would be useful. This study applied a PCR-based method to detect of <it>C. chauvoei </it>in 25 muscle and blood samples, 114 manure samples, 84 soil samples and 33 samples from the biogas process.</p> <p>Methods</p> <p>Muscle tissues from suspected cases of blackleg were analysed both by the standard culture method followed by biochemical identification and by PCR, with and without preculture. To investigate whether muscle tissue samples are necessary, samples taken by swabs were also investigated. Samples from a biogas plant and manure and soil from farms were analysed by culture followed by PCR. The farms had proven cases of blackleg. For detection of <it>C. chauvoei </it>in the samples, a specific PCR primer pair complementary to the spacer region of the 16S-23S rRNA gene was used.</p> <p>Results</p> <p><it>Clostridium chauvoei </it>was detected in 32% of muscle samples analysed by culture with identification by biochemical methods and in 56% of cases by culture in combination with PCR. <it>Clostridium chauvoei </it>was detected in 3 (out of 11) samples from the biogas plants collected before pasteurisation, but samples taken after pasteurisation and after digestion all tested negative. <it>Clostridium chauvoei </it>was not detected in any soil or silage samples and only one manure samples tested positive.</p> <p>Conclusion</p> <p>The diagnostic method used for <it>C. chauvoei </it>was not applicable in estimating the risk of blackleg on particular pastures from manure or soil samples, but found to be highly useful for clinical samples.</p

Spatial and temporal investigations of reported movements, births and deaths of cattle and pigs in Sweden

<p>Abstract</p> <p>Background</p> <p>Livestock movements can affect the spread and control of contagious diseases and new data recording systems enable analysis of these movements. The results can be used for contingency planning, modelling of disease spread and design of disease control programs.</p> <p>Methods</p> <p>Data on the Swedish cattle and pig populations during the period July 2005 until June 2006 were obtained from databases held by the Swedish Board of Agriculture. Movements of cattle and pigs were investigated from geographical and temporal perspectives, births and deaths of cattle were investigated from a temporal perspective and the geographical distribution of holdings was also investigated.</p> <p>Results</p> <p>Most movements of cattle and pigs were to holdings within 100 km, but movements up to 1200 km occurred. Consequently, the majority of movements occurred within the same county or to adjacent counties. Approximately 54% of the cattle holdings and 45% of the pig holdings did not purchase any live animals. Seasonal variations in births and deaths of cattle were identified, with peaks in spring. Cattle movements peaked in spring and autumn. The maximum number of holdings within a 3 km radius of one holding was 45 for cattle and 23 for pigs, with large variations among counties. Missing data and reporting bias (digit preference) were detected in the data.</p> <p>Conclusion</p> <p>The databases are valuable tools in contact tracing. However since movements can be reported up to a week after the event and some data are missing they cannot replace other methods in the acute phase of an outbreak. We identified long distance transports of cattle and pigs, and these findings support an implementation of a total standstill in the country in the case of an outbreak of foot-and-mouth disease. The databases contain valuable information and improvements in data quality would make them even more useful.</p