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Biomedical subjects

K D C Stärk

Publications and source records attributed to K D C Stärk.

At least 19 recordsLinked to original sources
PubMed2006

Serological responses of adult dogs to revaccination against distemper, parvovirus and rabies.

Serum antibody titres to canine distemper virus (CDV), canine parvovirus (CPV) and rabies were measured in dogs that had not been revaccinated annually and compared with the titres in a control group of regularly vaccinated animals; 83 per cent (171 of 207) of the dogs vaccinated against CDV one or more years earlier had serum neutralising antibody titres equal to or greater than 16; 64 per cent (136 of 213) of the dogs vaccinated against CPV one or more years earlier had haemagglutination inhibiting titres equal to or greater than 80; and 59 per cent (46 of 78) of the dogs vaccinated against rabies two or more years earlier had serum neutralising antibody titres equal to or greater than 0.5 iu/ml. Three weeks after a single booster vaccination the dogs' antibody titres against CDV had increased above the threshold level in 94 per cent of the dogs, against CPV in 68 per cent, and against rabies in 100 per cent.

Animals↗
PubMed2006

No evidence of bluetongue virus in Switzerland.

We report the results of the first survey for antibody against bluetongue virus (BTV) that was conducted in Switzerland in the year 2003. In a nationwide cross-sectional study with partial verification, 2437 cattle sera collected from 507 herds were analysed using competitive enzyme-linked immunosorbent assays (c-ELISA). To adjust for misclassification, 158 sera, including 86 that were recorded equivocal in Switzerland, were sent to the Office Internationale des Epizooties designated regional reference laboratory in the UK for confirmation. No BTV antibody was detected in any of these samples, confirming the absence of BTV from Switzerland in 2003. The specificity of the c-ELISA used in Switzerland for individual Swiss cattle was calculated to be 96.5%. The mean herd sensitivity achieved in our survey ranged from 78.9% to 98.8% depending on the with-in herd prevalence and test sensitivity used for the calculations. The cumulated confidence level achieved with the survey based on a minimal expected prevalence of 2%, was 99.99% and therefore it was concluded that there was no evidence of BTV circulation in Switzerland in 2003.

Animals↗
PubMed2006

Establishment of an early warning system against bluetongue virus in Switzerland.

Bluetongue (BT) is a vector-borne animal disease of economical importance due to the international trade restrictions likely to be put into place in a country once the infection is discovered. The presence of BT and its vectors in countries adjacent to Switzerland stresses the need of implementing a surveillance system and to raise disease awareness among potential stakeholders. A national survey in Switzerland 2003 indicated freedom of Bluetongue virus (BTV), although a single individual of the main BT vector Culicoides imicola was caught in the canton of Ticino. The survey also demonstrated that potential BT vectors, C. obsoletus and C. pulicaris are locally abundant in Switzerland. Therefore, a new surveillance method based on sentinel herds in high risk areas was implemented in 2004 for the early detection of both an incursion of BT vectors into Switzerland, and potential virus circulation among cattle.

Animals↗
PubMed2006

Phenon cluster analysis as a method to investigate epidemiological relatedness between sources of Campylobacter jejuni.

AIMS: To develop a method for assessing the relative epidemiological significance of possible infection sources for human campylobacteriosis. METHODS AND RESULTS: Using fluorescent amplified fragment length polymorphism (AFLP), 243 apparently epidemiologically unrelated Campylobacter jejuni isolates were genotyped (77 human, 46 cattle, 49 pet and 71 poultry isolates). In total 136 different phena were identified, of which 48 were clusters grouping at least two isolates. Isolates from different sources were frequently clustered together, underlining the high degree of source mixing and the lack of host specificity of C. jejuni. The phena were classified into different phenon types according to the sources of the isolates they contained. The occurrence of these phenon types was analysed using an area-proportional Euler diagram to describe epidemiological relatedness among C. jejuni isolates. Group separation statistics revealed that 43% of analysed human isolates expressed maximum similarity to other human isolates, 9% to cattle isolates, 21% to pet isolates and 27% to poultry isolates; these results were in accordance with the pattern observed in the phenon cluster analysis. CONCLUSIONS: Based on the grouping of strains into molecular similarity clusters, ecological patterns between sources can be investigated. SIGNIFICANCE AND IMPACT OF THE STUDY: This approach is a new methodological contribution to establish the relative epidemiological significance of concurrent infection sources.

Animals↗
PubMed2006

Bluetongue vector species of Culicoides in Switzerland.

Switzerland is historically recognized by the Office Internationale des Epizooties as free from bluetongue disease (BT) because of its latitude and climate. With bluetongue virus (BTV) moving north from the Mediterranean, an entomological survey was conducted in Switzerland in 2003 to assess the potential of the BTV vectors present. A total of 39 cattle farms located in three geographical regions, the Ticino region, the Western region and the region of the Grisons, were monitored during the vector season. Farms were located in areas at high risk of vector introduction and establishment based on the following characteristics: annual average temperature > 12.5 degrees C, average annual humidity >or= 60%, cattle farm. Onderstepoort black light traps were operated at the cattle farms generally for one night in July and one night in September. A total of 56 collections of Culicoides (Diptera: Ceratopogonidae) were identified morphologically. Only one single individual of Culicoides (Avaritia) imicola, the major Old World vector of BTV, was found in July 2003 in the Ticino region, one of the southernmost regions of Switzerland. In the absence of further specimens of C. imicola from Switzerland it is suggested that this individual may be a vagrant transported by wind from regions to the south of the country where populations of this species are known to occur. Alternative potential BTV vectors of the Culicoides (Culicoides) pulicaris and Culicoides (Avaritia) obsoletus complexes were abundant in all sampled regions with individual catches exceeding 70 000 midges per trap night.

Altitude↗
PubMed2005

Evaluation of an antimicrobial resistance monitoring program for Campylobacter in poultry by simulation.

An ideal national resistance monitoring program should deliver a precise estimate of the resistance situation for a given combination of bacteria and antimicrobial at a low cost. To achieve this, decisions need to be made on the number of samples to be collected at each of different possible sampling points. Existing methods of sample size calculation can not be used to solve this problem, because sampling decisions do not only depend on the prevalence of resistance and sensitivity and specificity of resistance testing, but also on the prevalence of the bacteria, and test characteristics of isolation of these bacteria. Our aim was to develop a stochastic simulation model that optimized a national resistance monitoring program, taking multi-stage sampling, imperfect sensitivity and specificity of diagnostic tests, and cost-effectiveness considerations into account. The process of resistance testing of Campylobacter spp. isolated from cloacal swab samples from poultry was modeled using a Markov Chain Monte Carlo model. Different sampling scenarios on the number of flocks to be tested, the number of birds from each flock, and the number of campylobacter colonies submitted to susceptibility testing were evaluated regarding the precision of the resulting prevalence estimate. Precision of the prevalence estimate was defined as the absolute difference between apparent and true prevalence of resistance. A partial budget approach was utilized to find the most cost-effective combination of samples to obtain a defined precision of the prevalence estimate. For a sampling scenario testing 100 flocks, five birds per flock, and one campylobacter colony per sample, the median error of the prevalence estimate was 2.5%, and 95% of the simulations resulted in an error of 7% or less. When the total number of samples was kept constant, maximizing the number of flocks tested, and only testing one bird per flock resulted in the most precise prevalence estimate. Submitting more than one campylobacter colony to resistance testing did not improve the prevalence estimate. Partial budget analysis indicated that the most cost-effective strategy was testing of two birds per flock, and submitting one colony per sample to resistance testing.

Animals↗
PubMed2005

Clinical herd health, farm management and antimicrobial resistance in Campylobacter coli on finishing pig farms in Switzerland.

The world-wide increase of antimicrobial resistance in micro-organisms complicates medical treatment of infected humans. We did a risk-factor analysis for the prevalence of antimicrobial resistant Campylobacter coli on 64 Swiss pig finishing farms. Between May and November 2001, 20 faecal samples per farm were collected from the floor of pens holding finishing pigs shortly before slaughter. Samples were pooled and cultured for Campylobacter species. Isolated Campylobacter strains were tested for resistance against selected antimicrobials. Additionally, information on herd health and management aspects was available from another study. Because data quality on the history of antimicrobial use on the farms was poor, only non-antimicrobial risk factors could be analysed. Statistical analyses were performed for resistance against ciprofloxacin, erythromycin, streptomycin, tetracycline, and for multiple resistance, which was defined as resistance to three or more antimicrobials. Risk factors for these outcomes--corrected for dependency of samples at herd level--were analysed in five generalised estimation-equation models. Prevalence of antimicrobial resistance among Campylobacter isolates was ciprofloxacin 26.1%, erythromycin 19.2%, streptomycin 78.0%, tetracycline 9.4%, and multiple resistance 6.5%. Important risk factors contributing to the prevalence of resistant strains were shortened tails, lameness, skin lesions, feed without whey, and ad libitum feeding. Multiple resistance was more likely in farms which only partially used an all-in-all-out system (OR = 37), or a continuous-flow system (OR = 3) compared to a strict all-in-all-out animal-flow. Presence of lameness (OR = 25), ill-thrift (OR = 15), and scratches at the shoulder (OR = 5) in the herd also increased the odds for multiple resistance. This study showed that on finishing farms which maintained a good herd health status and optimal farm management, the prevalence of antimicrobial resistance was also more favourable.

Animal Husbandry↗
PubMed2005

Where should the effort be put to reduce the Salmonella prevalence in the slaughtered swine carcass effectively?

Infection with Salmonella Typhimurium is seldom associated with clinical disease in pigs. However, control is important as the public is concerned about the human health impact. The producers, the abattoirs and the authorities are interested in implementing procedures to mitigate this risk. To evaluate the effect of different procedures, a stochastic risk model was developed to simulate the prevalence of Salmonella infection during the production process from the live pig on the farm, to the final carcass. This paper describes the model and findings of simulating different control scenarios. The variables with maximum effect on the Salmonella prevalence on the final carcass were (1) number of herds with a high prevalence of Salmonella, (2) singeing efficiency, (3) contamination and cross-contamination at degutting and (4) cross-contamination during handling. However, improvement of any single factor in isolation had a limited impact upon the level of contamination. The largest reduction was observed when several factors were improved concurrently.

Animals↗
PubMed2005

Campylobacter spp. in dogs and cats in Switzerland: risk factor analysis and molecular characterization with AFLP.

A 1-year cross-sectional study was carried out to determine the prevalence, risk factors for carriage, and genetic diversity of Campylobacter spp. in healthy dogs and cats in Switzerland. Veterinary practitioners collected samples from 1268 animals (all ages) presented for vaccination. The prevalence of Campylobacter spp. in 634 dogs and 596 cats that were eligible for the study was 41.2% (confidence interval 95%: 37.3-45.1%) and 41.9% (CI 95%: 37.9-46%), respectively. Risk factors identified for carriage of Campylobacter jejuni were found to be different from risk factors for C. upsaliensis/C. helveticus. Young animals (< or =3 years) had significantly higher odds of carrying C. upsaliensis/C. helveticus than older animals (OR 1.8-3.3), whereas for C. jejuni carriage, the age was not a risk factor. Amplified fragment length polymorphism (AFLP) genotyping revealed heterogeneity among C. jejuni strains and was found to clearly separate C. helveticus from C. upsaliensis. It was shown that cats more often carry C. helveticus with an estimated prevalence of 28.2%, whereas dogs mainly are carrying C. upsaliensis.

Animals↗
PubMed2005

[Methods for population-based herd sanitation: an overview].

There is a considerable number of methods available for the development, maintenance and surveillance of specific-pathogen-free herds. The selection of a method for a specific remediation project is primarily dependent on the goal, the epidemiology of the agent to be eradicated, the feasibility and the available resources. At the beginning of the remediation programme, methods are required for the classification of the herd status. Clinical and analytical diagnostic tests may be used for individual herds or in an entire area. The interpretation of test results applied within a population deserves special attention. A series of techniques are available - alone or in combination - to remediate a herd that was classified as being infected: systematic treatment, vaccination, elimination of infected individual animals ("test and remove"), partial depopulation or total population (stamping out). These strategies are typically accompanied by cleaning and disinfection. After the remediation, the status of the herd needs to be certified and maintained. For the documentation of the status, monitoring and surveillance strategies such as clinical follow-up visits, notification systems and random sampling can be applied. When planning random surveys, statistical and epidemiological considerations are relevant. For the sustainable maintenance of the pathogen-free status, biosecurity measures at the individual farm level, but also broader approaches such as import restrictions, early warning systems and surveillance programmes are needed. General awareness regarding unusual clinical signs needs to be promoted among farmers and veterinarians. The longer a disease or an agent is absent from a herd or region, the lower becomes the risk awareness. In such a situation, mistakes can occur leading to an increased risk of re-infection.

Animal Diseases↗
PubMed2004

Estimating the probability and level of contamination with Salmonella of feed for finishing pigs produced in Switzerland--the impact of the production pathway.

Contaminated feed is a source of infection with Salmonella for livestock, including pigs. Because pigs rarely show clinical signs of salmonellosis, undetected carriers can enter the food production chain. In a "Farm to Fork" food safety concept, safe feed is the first step for ensuring safe food. Heat treatment or adding organic acids are process steps for reducing or eliminating a contamination with Salmonella. The aims of this study were (I) to estimate the probability and the level of Salmonella contamination in batches of feed for finishing pigs in Swiss mills and (II) to assess the efficacy of specific process steps for reducing the level of contamination with Salmonella. A quantitative release assessment was performed by gathering and combining data on the various parameters having an influence on the final contamination of feed. Fixed values and probability distributions attributed to these parameters were used as input values for a Monte Carlo simulation. The simulation showed that-depending on the production pathway-the probability that a batch of feed for finishing pigs contains Salmonella ranged from 34% (for feed on which no specific decontaminating step was applied) to 0% (for feed in which organic acids were added and a heat treatment was implemented). If contamination occurred, the level of contamination ranged from a few Salmonella kg(-1) feed to a maximum of 8E+04 Salmonella kg(-1) feed. Probability and levels of contamination were highest when no production process able to reduce or eliminate the pathogen was implemented. However, most of the Swiss production was shown to undergo some kind of decontaminating step. A heat treatment, in combination with the use of organic acids, was found as a solution of choice for the control of Salmonella in feed.

Animal Feed↗
PubMed2004

[Anaplasmosis in a Swiss dairy farm: an epidemiological outbreak investigation].

In summer of 2002, a case of severe clinical bovine anaplasmosis caused great losses in a dairy farm of an animal trader in Grisons. This article outlines the general approach of an outbreak investigation considering the case of anaplasmosis as an example. The goals of such investigations are to identify and eliminate the source of a disease outbreak in order to avoid additional cases. In addition, recommendations should be developed for preventing or limiting the magnitude of similar outbreaks in the future. In the outbreak presented, the causative agents were probably brought into the dairy farm by animal trade. Due to the large herd size, a missing quarantine for new animals and the coinfection with several pathogens, this case led to a high number of fatalities. The investigations of this outbreak demonstrated the importance of an universal and consistent identification of individual animals for the reconstruction of their movements. The veterinary practitioner should be reminded to act cautiously when facing strange clinical cases and to also consider "exotic diseases" as a possible cause.

Anaplasmosis↗
PubMed2004

[Enzootic pneumonia (EP) in Swiss swine herds after area-wide eradication: epidemiological analysis of outbreaks occurring between 1999 and 2003].

In a retrospective analysis, infections of swine herds with Enzootic Pneumonia (EP), occurring after the regional eradication programme had been completed, were evaluated and described according to epidemiological criteria. The aim of this study was to obtain interim results about status, progress and trends of the area-wide eradication in Switzerland over all regions involved in the programme. The population comprised pig farms with eradication of EP completed by the end of 2002. Incidence of EP infection was calculated for the years 2000-2003. Seasonal effects, influences from production-type, herd size, and pig density in the surrounding area on incidences of EP outbreaks were investigated. In 2000-2002, annual incidences were steadily decreasing from 3.1% to 2.0%, and they showed great regional variation. In 2003, contrary to the long-term trend, a minor increase of overall incidence from 2.0% to 2.1% was observed while the incidence for breeding-only farms continued to recede. Possible explanations for this are discussed. Previous observations on EP infections accumulating in the cold season could not be confirmed. Large farms, finishing farms, and farms located in densely populated pig areas as well as farms being part of multisite production rings had a higher risk of infection. In spite of occurrence of EP outbreaks in eradicated areas, the current status of the area-wide eradication is promising, and a further decline in incidence of EP infection can be expected in the future.

Animal Husbandry↗
PubMed2003

The construction and evaluation of a questionnaire to identify quantitative criteria for evaluating national Veterinary Services.

This article presents the first part of a large-scale study aimed at developing a method for collecting standard information, based on quantitative criteria, about the national Veterinary Services of Member Countries of the OIE (World organisation for animal health). This information can then be used to assess such Veterinary Services in terms of quality and performance, or for accreditation. The study identified objective and relevant criteria for characterising Veterinary Services and an extensive questionnaire was developed, covering all aspects of the structures and functions of national Veterinary Services, which was sent to a broad range of OIE Member Countries. Each question and its answers were then evaluated and validated. In this way, 49 questions suitable for obtaining quantitative criteria to describe Veterinary Services were identified. In the next step of the study, this complex set of data will be further analysed.

Animals↗
PubMed2003

Quality assurance applied to animal disease surveillance systems.

Monitoring and surveillance systems (MOSS) are essential activities for official Veterinary Services. In addition, the increased trade in animals and animal products over recent years has increased the importance of international disease reporting. A reliable surveillance system is the key to early warning of a change in the health status of any animal population. Such a system is also essential for providing evidence about the absence of diseases or in determining the extent of a disease which is known to be present. The authors discuss a set of methods and approaches for evaluating the quality of surveillance and survey systems. Certain steps are required when assessing the quality of a service or product. Various approaches for quality assessment are available and the suitability of each method depends on the objective of the evaluation. An essential basic requirement is, however, to use an objective, transparent and systematic approach. The evidence collected and the analyses used to reach conclusions must be of such high quality that the results are acceptable to both the management of the MOSS and the assessor. Repeated discussions and negotiations may be necessary to reach consensus, particularly if the judgement affects activities between trading partners. Well-documented MOSS with specified objectives and integrated quality assurance mechanisms are likely to be easier to evaluate.

Animal Diseases↗
PubMed2003

Evaluation of the safety assurance level for Salmonella spp. throughout the food production chain in Switzerland.

In Switzerland. the safeguarding of food is the responsibility of industry, organizations, and governmental authorities. The dispersion of the tasks and the diversity of implemented safety measures among involved stakeholders do not allow a general overview of the national safety assurance level provided. A comprehensive evaluation of the level of safety assurance provided for foodborne pathogens such as Salmonella spp. is therefore lacking, and the prevalence of Salmonella spp. at various points in the food production chain is not known. The objectives of this study were to (i) collect data on safety measures implemented throughout the food production chain in Switzerland regarding Salmonella spp.; (ii) evaluate the safety assurance level for Salmonella spp. at each step of the production chain for chicken meat, pork, beef, and milk and dairy products (bovine origin); and (iii) gather data on the prevalence of the pathogen at each step. Data on implemented safety assurance measures for Salmonella spp. were gathered from the various stakeholders in the food production chain. The data were analyzed by a semiquantitative method that considered the quality and relevance of the implemented safety measures for Salmonella spp. The safety assurance level for Salmonella spp. was evaluated from "no safety assurance" to "very good safety assurance." Available results of testing for Salmonella spp. from 1998 to 2000 were used for calculating the prevalence of the pathogen throughout the food production chain. The results showed a varying safety assurance level for Salmonella spp. throughout the food production chain. Strengths (e.g., feed production for chickens) and weaknesses (e.g., pork production) were observed. These results serve as a basis for a rational optimization of the system.

Animals↗
PubMed2003

A semiquantitative approach for evaluating safety assurance levels for Salmonella spp. throughout a food production chain.

Various safety assurance measures are implemented in Switzerland throughout the food production chain to prevent foods of animal origin from being contaminated with Salmonella. The data that are generated from the implementation of these measures are dispersed and heterogeneous. This hinders a general overview and makes a comprehensive national evaluation of the safety assurance level difficult. A semiquantitative method that considers the quality and relevance of the various safety assurance measures for Salmonella spp. was developed. The method uses the data generated from the implementation of safety assurance measures on a national basis (gathered by interviewing stakeholders in the production step). By assembling and analyzing the data systematically, the safety assurance level for Salmonella spp. can be evaluated at every step of the food production chain. This method allows the detection of strengths and weaknesses of the safety system. The systematic evaluation procedures permit comparisons between production steps and product categories. The method was used for evaluating the safety assurance levels throughout the production chain of eggs and egg products in Switzerland. Results of the analysis showed that the overall safety assurance levels for Salmonella spp. at all production steps for eggs and egg products were good. The relatively straightforward implementation of the method made it particularly appropriate in the context of a preliminary evaluation. The method does not have the same high level of detail that is provided by microbial quantitative risk assessments, but it allows an analyst to provide meaningful results when the large amount of data required for a quantitative approach are not present while including the entire "farm to fork" continuum. It may be used as a basis for more in-depth assessments of food safety levels within various production sectors. The method could be adapted for evaluating the safety assurance for other zoonotic foodborne pathogens of interest, such as Campylobacter spp.

Animals↗