Salmonella in pigs

In recent years several incidents of feed-borne spread of Salmonella spp. have been documented in Swedish pig herds, including serotypes previously not associated with pigs. In this thesis two feed-associated serotypes (S Cubana and S Yoruba) were compared with two serotypes commonly detected in pigs (S Typhimurium and S Derby). The overall aim of the thesis was to increase knowledge about the feed-associated serotypes, with special focus on their infection dynamics in pigs. In 2003, a contamination in a feed mill caused the spread of S Cubana via feed to a number of pig herds. Questions raised during that outbreak led to the design of the present PhD project. The outbreak was analysed and in experimental studies pigs were inoculated orally with one of four serotypes, in three different doses (103, 106 or 109 colony forming units). Pigs were then monitored for eight weeks in order to determine differences among serotypes in faecal shedding, serological response and body distribution. Differences among serotypes were revealed as regards infectious dose, serological response and distribution to extra-intestinal organs and tissues. The data obtained were used for a mathematical modelling approach on the dynamics of faecal salmonella shedding and the immune response in pigs. The results showed that the dynamics of faecal shedding during infection were strongly associated with the challenge dose but weakly associated with the infection serotype. In order to investigate transmission of the four serotypes, uninfected pigs were introduced to salmonella-shedding pigs in a late stage of infection as well as to contaminated pens. All four serotypes were transmitted to at least one of the naïve pigs, but the overall transmission was low in both experimental settings. In conclusion, these studies showed that S Cubana may differ in some aspects regarding infection dynamics in pigs. However, the inoculation dose had a larger impact than the serotype. Thus, the level of infection in a herd infected with Salmonella spp. may be more indicative of what control measures that are needed, than the serotype involved

Salmonella Fecal Shedding and Immune Responses are Dose- and Serotype- Dependent in Pigs

Despite the public health importance of Salmonella infection in pigs, little is known about the associated dynamics of fecal shedding and immunity. In this study, we investigated the transitions of pigs through the states of Salmonella fecal shedding and immune response post-Salmonella inoculation as affected by the challenge dose and serotype. Continuous-time multistate Markov models were developed using published experimental data. The model for shedding had four transient states, of which two were shedding (continuous and intermittent shedding) and two non-shedding (latency and intermittent non-shedding), and one absorbing state representing permanent cessation of shedding. The immune response model had two transient states representing responses below and above the seroconversion level. The effects of two doses [low (0.65×106 CFU/pig) and high (0.65×109 CFU/pig)] and four serotypes (Salmonella Yoruba, Salmonella Cubana, Salmonella Typhimurium, and Salmonella Derby) on the models' transition intensities were evaluated using a proportional intensities model. Results indicated statistically significant effects of the challenge dose and serotype on the dynamics of shedding and immune response. The time spent in the specific states was also estimated. Continuous shedding was on average 10–26 days longer, while intermittent non-shedding was 2–4 days shorter, in pigs challenged with the high compared to low dose. Interestingly, among pigs challenged with the high dose, the continuous and intermittent shedding states were on average up to 10–17 and 3–4 days longer, respectively, in pigs infected with S. Cubana compared to the other three serotypes. Pigs challenged with the high dose of S. Typhimurium or S. Derby seroconverted on average up to 8–11 days faster compared to the low dose. These findings highlight that Salmonella fecal shedding and immune response following Salmonella challenge are dose- and serotype-dependent and that the detection of specific Salmonella strains and immune responses in pigs are time-sensitive

Direct and indirect transmission of four Salmonella enterica serotypes in pigs

<p>Abstract</p> <p>Background</p> <p>Feed-borne spread of <it>Salmonella </it>spp. to pigs has been documented several times in recent years in Sweden. Experiences from the field suggest that feed-associated serotypes might be less transmittable and subsequently easier to eradicate from pig herds than other serotypes more commonly associated to pigs. Four <it>Salmonella </it>serotypes were selected for experimental studies in pigs in order to study transmissibility and compare possible differences between feed-assoociated (<it>S </it>Cubana and <it>S </it>Yoruba) and pig-associated serotypes (<it>S </it>Derby and <it>S </it>Typhimurium).</p> <p>Methods</p> <p>Direct contact transmission was studied in four groups of pigs formed by six 10-week-old salmonella negative pigs commingled with two fatteners excreting one of the four salmonella serotypes. Indirect transmission was studied by putting six 10-week-old salmonella negative pigs in each of four salmonella contaminated rooms. Each room had previously housed a group of pigs, excreting one of the four selected serotypes.</p> <p>All pigs were monitored for two weeks with respect to the faecal excretion of salmonella and the presence of serum antibodies. At the end of the trial, eight samples from inner tissues and organs were collected from each pig at necropsy.</p> <p>Results</p> <p>In the four direct transmission groups, one pig shed <it>Salmonella </it>(Cubana) at one occasion. At necropsy, <it>S </it>Typhimurium was isolated from one pig.</p> <p>In the indirect transmission groups, two pigs in the Yoruba room and one pig in each of the other rooms were excreting detectable levels of <it>Salmonella </it>once during the study period of two weeks. At necropsy, <it>S </it>Derby was isolated from one of six pigs in the Derby room and <it>S </it>Typhimurium was isolated from four of the six pigs in the Typhimurium room.</p> <p>No significant serological response could be detected in any of the 48 pigs.</p> <p>Conclusions</p> <p>These results show that all four selected serotypes were able to be transmitted in at least one of these field-like trials, but the transmission rate was low in all groups and no obvious differences between feed-associated and pig-associated serotypes in the transmission to naïve pigs and their subsequent faecal shedding were revealed. However, the post mortem results indicated a higher detection of <it>S </it>Typhimurium in the ileocecal lymph nodes of pigs introduced into a contaminated environment in comparison with the other three serotypes.</p

Antibiotic Resistance in Escherichia coli from Pigs in Organic and Conventional Farming in Four European Countries

Organic pig production differs in many ways from conventional production of pigs, e.g., in antibiotic use, herd structure, feeding regimes, access to outdoor areas and space allowance per pig. This study investigated if these differences result in a lower occurrence of antibiotic resistance in organic slaughter pigs in Denmark, France, Italy and Sweden. Samples were taken from the colon content and/or faeces and minimum inhibitory concentrations (MIC) of ten antibiotics were determined in isolates of Escherichia coli. In addition, the proportion of tetracycline (TET) resistant E. coli in colon content and/or faeces from individual pigs was determined. In all four countries the percentage resistance to ampicillin, streptomycin, sulphonamides or trimethoprim was significantly lower in E. coli from organic pigs. In France and Italy, the percentage of isolates resistant to chloramphenicol, ciprofloxacin, nalidixic acid or gentamicin was also significantly lower in the E. coli from organic pigs. Resistance to cefotaxime, was not found in any country. The percentage of E. coli isolates resistant to TET as well as the proportion of TET-resistant E. coli was significantly lower in organic than in conventional pigs, except in Sweden where TET-resistance was equally low in both production types. There were also differences between countries within production type in the percentage resistance to individual antibiotics as well as the proportion of TET-resistant E. coli with lower median proportions in Sweden and Denmark compared to France and Italy. The study shows that in each of the four countries resistance in intestinal E. coli was less common in organic than in conventional pigs, but that there were also large differences in resistance between countries within each production type, indicating that both country- and production-specific factors influence the occurrence of resistance

Longitudinal study of the immune response and memory following natural bovine respiratory syncytial virus infections in cattle of different age

Human and bovine respiratory syncytial virus (HRSV and BRSV) are closely genetically related and cause respiratory disease in their respective host. Whereas HRSV vaccines are still under development, a multitude of BRSV vaccines are used to reduce clinical signs. To enable the design of vaccination protocols to entirely stop virus circulation, we aimed to investigate the duration, character and efficacy of the immune responses induced by natural infections. The systemic humoral immunity was monitored every two months during two years in 33 dairy cattle in different age cohorts following a natural BRSV outbreak, and again in selected individuals before and after a second outbreak, four years later. Local humoral and systemic cellular responses were also monitored, although less extensively. Based on clinical observations and economic losses linked to decreased milk production, the outbreaks were classified as moderate. Following the first outbreak, most but not all animals developed neutralising antibody responses, BRSV-specific IgG1, IgG2 and HRSV F- and HRSV N-reactive responses that lasted at least two years, and in some cases at least four years. In contrast, no systemic T cell responses were detected and only weak IgA responses were detected in some animals. Seronegative sentinels remained negative, inferring that no new infections occurred between the outbreaks. During the second outbreak, reinfections with clinical signs and virus shedding occurred, but the signs were milder, and the virus shedding was significantly lower than in naïve animals. Whereas the primary infection induced similar antibody titres against the prefusion and the post fusion form of the BRSV F protein, memory responses were significantly stronger against prefusion F. In conclusion, even if natural infections induce a long-lasting immunity, it would probably be necessary to boost memory responses between outbreaks, to stop the circulation of the virus and limit the potential role of previously infected adult cattle in the chain of BRSV transmission

Varumärkets personlighet : En kvalitativ studie om hur konsumenter tillskriver varumärken personlighetsdrag beroende på logotypens färg

Syfte: Denna studies syfte är att öka förståelsen för vilka personlighetsdrag konsumenter tillskriver varumärken beroende på logotypens färg. Metod: Eftersom studiens syfte har varit att öka förståelsen för ämnet har en kvalitativ metod använts och färgerna blå, grön, gul, röd och svart har legat till grund för undersökningen. För att samla in empiriskt material har semistrukturerade intervjuer utförts med tolv deltagare. Materialet har analyserats med hjälp av Aakers (1997) Brand Personality Scale samt tematisering. Resultat &amp; slutsats: Studiens resultat visar att den blå logotypen associeras med kompetens, den gröna med uppriktighet och den gula med spänning. Den röda logotypen har även den associerats med kompetens och den svarta med robusthet, i Aakers (1997) Brand Personality Scale. Reaktionerna för den blå och den gröna logotypen har visat sig vara enklast för deltagarna att placera samt visat sig överensstämma med tidigare forskningsresultat. Den gula, röda och svarta logotypen har upplevts svårare och resultaten har avvikit mer från tidigare forskning. Förslag till fortsatt forskning: Våra förslag för framtida forskning är att istället för att studera färger, studera vilken påverkan logotypens utformning har på varumärkets personlighet. Vidare kan framtidens forskning studera flerfärgade logotyper. Vår studie studerar endast en speciell subgrupp och framtida forskning kan därför studera en annan subgrupp för jämförelse. Uppsatsens bidrag: Som bidrag till framtida forskning ser vi att denna studie beskriver samband mellan färgerna blå, grön, gul, röd och svart och dimensionerna som återfinns i Aakers (1997) Brand Personality Scale. Detta tillägg ser vi skulle fungera som ett utvecklande ramverk och därför bidra till det teoretiska perspektivet i framtida studier utförda i Sverige. Som rekommendation kan företag rent praktiskt använda sig av dessa resultat när de ska välja färg för sin logotyp.  Aim: In this study we aim to increase understanding of the personality traits consumers ascribe to brands depending on the color of the logo. Method: Due to the aim of the study, which was to increase understanding of the topic, a qualitative method has been used. To collect empirical data semi-structured interviews were conducted with twelve participants. The material was analyzed using Aaker’s (1997) Brand Personality Scale and thematisation. Result &amp; Conclusions: Results show that the blue logo is associated with competence, green with sincerity and yellow with excitement. The red logo has also been associated with competence and the black with ruggedness, in Aaker’s (1997) Brand Personality Scale. The reactions of the blue and green logo has proven to be the easiest for the participants to place and shown to be consistent with previous research. The yellow, red and black logo has been perceived more difficult and the results have deviated more from previous research. Suggestions for future research: Our suggestions for future research is that instead of examining colors, examine the impact of the logo design in brand personality. Furthermore, future research could investigate multi-color logos. Our study examines only a specific subgroup and future research can explore a different subgroup for comparison. Contribution of the thesis: As a contribution to future research, this study describes the relationship between the colors blue, green, yellow, red and black and the dimensions found in Aakers (1997) Brand Personality Scale. This addition would serve as a developed framework and thus contribute to the theoretical perspective in future studies carried out in Sweden. As a recommendation, companies can practically use these results when they are designing their logo

Osteochondrosis, but not lameness, is more frequent among free-range pigs than confined herd-mates

Background: Organic pig production is expanding and amongst the objectives of organic farming are enhancing animal health and welfare. However, some studies have reported a higher prevalence of lameness and joint condemnation at slaughter in free-range/organic pigs than in conventionally raised pigs. Organic slaughter pigs have free-range housing in which indoor and outdoor access is compulsory, while in conventional farming the pigs are commonly confined to indoor pens. The present study evaluated the effects of free-range and confined housing on lameness prevalence in a herd of 106 finisher pigs, and whether osteochondrosis and Erysipelothrix rhusiopathiae associated arthritis influences these effects. We also evaluated the association between clinical lameness during the rearing period and joint condemnations at slaughter.Results: Seventy free-range and 36 confined housed fattener pigs were scored for their gait twice during the rearing period and 848 joints were evaluated post mortem. Osteochondrosis was more frequent among free-range than confined pigs (P &lt; 0.05), and when present it was also more severe (P &lt; 0.001). Pigs with more numerous and more severe osteochondral lesions had their gait affected more than did pigs with fewer such lesions (P &lt; 0.05). Hence it was a paradox that we did not detect more lameness among the free-range pigs than the confined pigs. E. rhusiopathiae associated arthritis was not diagnosed. The association between gait remarks/clinical lameness and joint condemnations at slaughter was not significant.Conclusions: The results indicate that free-range housing may have both positive and negative effects on locomotory traits. Free-range pigs may be less clinically affected by osteochondrosis than are confined pigs. One explanation for this effect may be strengthening of joint supportive tissue and pain relief promoted by exercise. Visual gait scoring missed serious joint lesions that probably were harmful to the pigs, and should therefore not be used as a sole indicator of joint/leg health in welfare inspection of pigs. The association between gait scores and joint condemnation appeared to be poor. This study was limited to one herd, and so more and larger studies on the effects of free-range housing on lameness severity and osteochondrosis development in pigs are recommended

Risk assessment as a tool for improving external biosecurity at farm level

Background: Biosecurity routines at herd level may reduce the probability of introduction of disease into the herd, but some measures may be regarded as expensive and cumbersome for the farmers. Custom-made measures based on individual farm characteristics may aid in improving the actual application of on-farm biosecurity. The aim of the study was to provide a tool for calculating the effects of different biosecurity measures and strategies on the individual farm level.A simple model was developed to assess the risk of disease introduction and the need for biosecurity measures in individual farms. To illustrate the general applicability of the tool, it was applied to theoretical examples of Swedish cattle and pig farms and diseases endemic in those animal species in the EU, in two scenarios with different between-farm contact patterns.Results: The model illustrated that the most important factors affecting the risk, and the effect of biosecurity measures such as quarantine routines and protective clothing, were the frequency of between- farm contacts and prevalence of the disease. The risk of introduction as well as the effect of biosecurity measures differed between farm types and disease transmission routes. Adapting contact patterns to mitigate a specific disease risk was as important as biosecurity measures for some farm types, but the largest effect was seen when combining biosecurity measures with more planned contact patterns.Conclusions: The risk assessment model proved useful for illustrating the risk of introduction of endemic diseases and the mitigating effect of different biosecurity measures on farm level. Model outputs could be used to justify prioritisation of measures or adapting contact patterns. The theoretic exercise of adjusting model inputs and comparing outputs may help veterinary advisors to understand farm-specific risks and motivate farmers to improve biosecurity in their individual farm, as it can be tailored to each farmer's needs and preferences

Effects of free-range and confined housing on joint health in a herd of fattening pigs

Background Free-range housing, in which pigs have access to both indoor and outdoor areas, is mandatory in organic pig production in Europe, but little is known about the effects of this housing on joint health in pigs. A high level of joint condemnations at slaughter has been reported in organic free-range pigs in Sweden, compared with pigs raised in conventional confined housing. We hypothesised that biomechanical forces imposed on the joints of pigs that range freely promote the development of osteochondrosis and lead to joint condemnation. We compared the prevalence of osteochondrosis and other joint lesions (e.g. arthritis, traumatic) in the elbow and hock joints of 91 crossbred Hampshire (Yorkshire×Landrace) fattening pigs that were housed in a free-range indoor/outdoor system with that in 45 pigs housed in confined indoor pens. Results A larger proportion of free-range than confined pigs had osteochondrosis in the elbow joints (69 vs. 50%, p<0.05), and a higher proportion of these joints in free-range pigs showed moderate or severe lesions (33 vs. 16%, p<0.05). The free-range pigs also showed a higher prevalence of osteochondrosis in the hock joints (83 vs. 62%, p<0.05) and a larger proportion of these joints had moderate or severe lesions (69 vs. 33%, p<0.001). At slaughter, 4.2% of the free-range pigs had condemned joints, all of which showed severe osteochondrosis, while no joints of confined pigs were condemned. Conclusions In this experiment the prevalence of osteochondrosis in the elbow and the hock was higher, and lesions were more severe, in free-range than in confined pigs, suggesting that free-range housing increases the risk of acquiring osteochondrosis. Increased biomechanical stress to vulnerable joint structures may be the mechanism behind this effect, however more studies are needed to verify these results. This study suggests that modification of housing, and breeding for joints that are more adapted to free-range movement may be needed in free-range pig production. Severe osteochondrosis is a cause of joint condemnation, but the condemnation rate at slaughter underestimates the actual frequency of joint lesions and hence is a poor assessment of joint health

Sportify : Utvecklingen av en digital medlemshemsida med fokus på användbarhet, navigerbarhet och trovärdighet

To enable sports associations to grow and effectively interact with their members with- out increasing the administrative workload significantly, an e-membership web application can be used. For this web application to be efficient and adopted by the members of the association, it needs to be useful, easy to navigate, and trustworthy for both the members and the administrators of the association. In this study, a web application was developed and tested in close collaboration with Linköpings Atletklubb to fulfill the previously men- tioned requirements. The study found that logical functionality affects usability, clarity of links and labels, such as menu options, affects navigability, and correct information and professional design contribute to trustworthiness in a positive manner