Characteristics of shiga toxin-producing Escherichia coli isolated from Swiss raw milk cheese within a 3-year monitoring program.

Food is an important vehicle for transmission of Shiga toxin-producing Escherichia coli (STEC). To assess the potential public health impact of STEC in Swiss raw milk cheese produced from cow's, goat's, and ewe's milk, 1,422 samples from semihard or hard cheese and 80 samples from soft cheese were examined for STEC, and isolated strains were further characterized. By PCR, STEC was detected after enrichment in 5.7% of the 1,502 raw milk cheese samples collected at the producer level. STEC-positive samples comprised 76 semihard, 8 soft, and 1 hard cheese. By colony hybridization, 29 STEC strains were isolated from 24 semihard and 5 soft cheeses. Thirteen of the 24 strains typeable with O antisera belonged to the serogroups O2, O22, and O91. More than half (58.6%) of the 29 strains belonged to O:H serotypes previously isolated from humans, and STEC O22:H8, O91:H10, O91:H21, and O174:H21 have also been identified as agents of hemolytic uremic syndrome. Typing of Shiga toxin genes showed that stx(1) was only found in 2 strains, whereas 27 strains carried genes encoding for the Stx(2) group, mainly stx(2) and stx(2vh-a/b). Production of Stx(2) and Stx(2vh-a/b) subtypes might be an indicator for a severe outcome in patients. Nine strains harbored hlyA (enterohemorrhagic E. coli hemolysin), whereas none tested positive for eae (intimin). Consequently, semihard and hard raw milk cheese may be a potential source of STEC, and a notable proportion of the isolated non-O157 STEC strains belonged to serotypes or harbored Shiga toxin gene variants associated with human infections.

[Livestock owners with specifically increased disease awareness for Bluetongue: A new approach to disease surveillance]. / Tierhalter mit gezielt erhöhter "Disease Awareness" für die Blauzungenkrankheit: Ein neuer Ansatz in der Seuchenüberwachung.

For the first time in Switzerland, specifically trained livestock owners were included in a national disease surveillance program by the Federal Veterinary Office. A questionnaire on data about clinical and epidemiological aspects of Bluetongue Disease (BT) as well as on herd management was completed by 26 sheep owners three months after they had attended a training course about BT. The control group, consisted of 264 randomly selected sheep and cattle owners who had not visited a training course. Results showed that disease awareness for BT after attending the training course was considerably increased. This was especially evident in the better knowledge of the participants about the great number of possible symptoms. Training courses with the objective of increased disease awareness of livestock owners are an efficient, cost-effective instrument in control programs for exotic diseases.

Data quality of animal health records on Swiss dairy farms.

High-quality data are essential for veterinary surveillance systems, and their quality can be affected by the source and the method of collection. Data recorded on farms could provide detailed information about the health of a population of animals, but the accuracy of the data recorded by farmers is uncertain. The aims of this study were to evaluate the quality of the data on animal health recorded on 97 Swiss dairy farms, to compare the quality of the data obtained by different recording systems, and to obtain baseline data on the health of the animals on the 97 farms. Data on animal health were collected from the farms for a year. Their quality was evaluated by assessing the completeness and accuracy of the recorded information, and by comparing farmers' and veterinarians' records. The quality of the data provided by the farmers was satisfactory, although electronic recording systems made it easier to trace the animals treated. The farmers tended to record more health-related events than the veterinarians, although this varied with the event considered, and some events were recorded only by the veterinarians. The farmers' attitude towards data collection was positive. Factors such as motivation, feedback, training, and simplicity and standardisation of data collection were important because they influenced the quality of the data.

Prevalence and characteristics of Shiga toxin-producing Escherichia coli in Swiss raw milk cheeses collected at producer level.

The aim of this study was to describe the prevalence, serotypes, and virulence genes of Shiga toxin-producing Escherichia coli (STEC) isolated from raw milk cheese samples collected at the producer level with the purpose of determining whether raw milk cheeses in Switzerland represent a potential source of STEC pathogenic for humans. Raw milk cheese samples (soft cheese, n = 52; semihard and hard cheese, n = 744; all produced from Swiss cows', goats', and sheep's milk) collected at the producer level throughout Switzerland within the national sampling plan during the period of March 2006 to December 2007 were analyzed. Of the 432 cheese samples obtained in the year 2006 and the 364 samples obtained in the year 2007, 16 (3.7%) and 23 (6.3%), respectively, were found to be stx positive. By colony dot-blot hybridization, non-O157 STEC strains were isolated from 16 samples. Of the 16 strains, 11 were typed into 7 E. coli O groups (O2, O15, O22, O91, O109, O113, O174), whereas 5 strains were nontypeable (ONT). Among the 16 STEC strains analyzed, stx(1) and stx(2) variants were detected in 1 and 15 strains, respectively. Out of the 15 strains with genes encoding for the Stx2 group, 4 strains were positive for stx(2), 6 strains for stx(2d2), 2 strains for stx(2-O118), 1 strain for stx(2-06), 1 strain for stx(2g), 1 strain for stx(2) and stx(2d2), and 1 strain for stx(2) and stx(2g). Furthermore, 3 STEC strains harbored E-hlyA as a further putative virulence factor. None of the strains tested positive for eae (intimin). Results obtained in this work reinforce the suggestion that semihard raw milk cheese may be a potential vehicle for transmission of pathogenic STEC to humans.

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.

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.

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.

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.

The impact of different housing systems on health and welfare of grower and finisher pigs in Switzerland.

The objective of the study was to evaluate the impact of housing systems on the health and welfare of grower and finisher pigs. Forty-seven "animal friendly" farms meeting Swiss criteria and participating in a Swiss subsidy program and 37 farms using traditional housing with slatted floors were evaluated in an epidemiological field study. Group-health evaluations and individual clinical examinations were performed during four visits to each farm. Evaluation of pig behaviours associated with health and welfare were assessed through indicators including presence of lesions on the snout, ears, shoulders, legs and tail. General group-health evaluations included lameness, respiratory disease, diarrhoea, ear biting, skin abnormalities, injuries, abscesses, sunburn, recumbency, ill-thrift and behavioural abnormalities such as dog sitting and tail biting. Data on management practices, medical treatment, mortality and results of slaughter inspections were also collected, and the type of housing described. Pooled faecal samples were collected and examined for intestinal parasites. Statistical analyses included descriptive statistics of indicators of health and welfare and logistic-regression analysis accounting for group effect using generalised estimation equation (GEE). Findings indicated a high health status of pigs in Swiss finishing farms. Data from the individual clinical examination were more sensitive compared to the group-health evaluations. Both the individual clinical examination and group-health evaluation indicated that "animal friendly" housing had positive effects on health and welfare of fattening pigs.

[Incidence of zoonoses in petting zoos and evaluation of hygiene measures to prevent the transmission to humans]. / Vorkommen von Zoonosen in Streichelzoos und Beurteilung der Hygienemassnahmen für die Ubertragung auf den Menschen.

In summer 2003, a study was performed in thirty Swiss petting zoos with the objective to determine the prevalence of zoonotic agents, and to describe hygiene measures implemented to reduce the risk of human infection. Fecal samples from different animal species were collected from the floor of pens to determine the prevalence of Salmonella spp., Campylobacter spp., verocytotoxin producing E. coli/ VTEC and Francisella tularensis. A questionnaire on hygiene measures, number of animals per species, housing system, care procedures and feeding was administered to every petting zoo to estimate exposure of visitors to zoonotic microorganisms. In total, 423 fecal samples were examined. Of these samples, 41 were positive for Campylobacter spp., which were mainly isolates from pigs and poultry (35% positive samples from each species). In pigs, 50% of the positive samples (6 samples) were typed as C. jejuni. The others were typed as C. coli (3) and C lan' (3), respectively. Five poultry isolates were typed as C. jejuni, and two as C. coli. Two samples were positive for Salmonella spp. Salmonella typhimurium was isolated from a goat, the other isolate could not be identified by serotyping. Neither Francisella tularensis nor verocytotoxin producing E. coli/ VTEC were found. The low prevalence of zoonotic microorganisms in Swiss petting zoos could be attributed to the cleanness of enclosures and animals, low stocking rates and good animal care. However, there is room for improvement concerning visitors' information on hygiene and hand washing. Furthermore, a strict separation between picnic - areas and animals should be enforced.

Health and welfare of dairy cows in different husbandry systems in Switzerland.

Our objective was to compare health and welfare of dairy cows kept in three types of husbandry systems: (1) tie stalls with regular exercise in summer but minimal outdoor access during winter (the reference level for analyses); (2) tie stalls with regular exercise in an exercise yard or pasture throughout the year; (3) loose-housing with regular access to an outdoor exercise yard or pasture. A total of 134 farms were visited (two to) three times in two years. Cows were examined for lameness, skin alterations at the hock joints, scars or injuries at the teats, and skin injuries at other locations. Lying and standing-up behavior were also evaluated. Farmers were requested to record the incidence of medical treatments for the whole observation period. A multivariable logistic-regression analysis was performed for each indicator of health and welfare with husbandry type, aspects of the housing system, farm characteristics, and management routines as the predictor variables. For welfare indicators recorded on individual animals, regression was performed correcting for clustering of observations within herds by Generalized Estimation Equation. Risk factors for the incidence of medical treatments were analyzed in a negative-binomial regression model. The odds for lameness were reduced for tie stalls with regular exercise throughout the year (OR=0.7). The prevalence of alterations at the hock joints was lower in loose-housing with regular outdoor exercise (OR=0.4). Teat injuries were less frequent in loose-housing with regular outdoor exercise (OR=0.1) and tie stalls with regular exercise (OR=0.4). Farms with loose-housing and regular outdoor exercise had a lower incidence of medical treatments (IR=0.6) than reference level farms.

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.

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.

[Health and welfare of dairy cows in different housing programs]. / Gesundheit und Wohlergehen von Milchkühen in verschiedenen Haltungsprogrammen.

The objective of this study was to evaluate the effect of two Swiss animal welfare friendly housing programs, 'regular access to outdoor facilities' (RAUS) and 'improved loose housing systems' (BTS) on health and welfare of dairy cows. During two years, the following indicators of health and welfare were observed on 136 randomly selected dairy farms: injuries around the joints, callosities, lameness, teat injuries, cleanliness, behaviour during lying and rising, body condition score, and incidence of medical treatments. Farms participating in both housing programs (BTS + RAUS) and farms with the program RAUS were compared to traditional farms that did not participate in a program. Housing system and management practice were recorded as additional factors influencing health and welfare of cows. Cows on farms participating in BTS + RAUS had, on average, fewer injuries around the hocks and fewer callosities at the carpal joints than cows in farms which did not participate in a housing program. Lameness was most frequent in cows of farms without housing program, followed by cows in tie stalls with the program RAUS and cows in loose housing systems with BTS + RAUS. There were fewer antibiotic treatments in farms with BTS + RAUS compared to the other farms.

[Zoonoses as a risk when associating with livestock or animal products]. / Zoonosen als Risiko im Umgang mit Tieren und tierischen Produkten.

The risk of zoonotic disease transmission when handling livestock or animal products is substantial. In industrialized countries, the classical zoonotic diseases such as tuberculosis or brucellosis are no longer in the foreground. Latent zoonoses such as salmonellosis and campylobacteriosis can cause serious disease in humans and have become a major public health problem during the past years. Since animals infected with these pathogens show only mild transient disease or no clinical signs at all, new concepts in the entire production line ("stable to table") are necessary in order to avoid human infection. Two emerging viruses with zoonotic potential--avian influenza virus and Nipah virus--have been found in Asia in 1997 and 1999. Both diseases had a major impact on disease control and public health in the countries of origin. In order to cope threats from infectious diseases, in particular those of public health relevance, a combined effort among all institutions involved will be necessary. The proposed "European Center for Infectious Diseases" and the "Swiss center for zoonotic diseases" could be a potential approach in order to achieve this goal.

[Evaluation of a monitoring system for assessing animal health in dairy cattle]. / Evaluation eines Monitoringsystems zur Erfassung der Tiergesundheit beim Milchvieh.

A monitoring system to assess animal health in dairy farms was developed and applied on 44 farms in an epidemiological study. The objective of the study was to evaluate the applicability of the system for long term monitoring of health data. For this purpose, the quality of the collected data and the acceptance of the system by farmers and veterinarians were investigated. Farmers recorded all health events using a form. Collected data was entered into a central database on a monthly basis. The recording of health data was easy to do and did not take a lot of time. Most of the farmers (89%) used less than 20 minutes per week for the recording. This time need was independent of the herd size. 66% of the farmers found it useful to record health data, especially for improving their overview on health of each single cow. Treatments were reported in 81% of the cases, inseminations and calving in 80% of the cases. All events were reported correctly and precise.

[Frequency and cost of health problems in Swiss dairy cows and their calves (1993-1994)]. / Häufigkeit und Kosten von Gesundheitsproblemen bei Schweizer Milchkühen und deren Kälbern (1993-1994).

Between July 1993 and July 1994 morbidity and management information related to dairy cows and their calves up to the age of 8 weeks were recorded in 113 randomly selected dairy herds. Also recorded were any costs incurred through disease and prevention. Blood and faeces were analysed with respect to selected pathogens. The health problems most frequently diagnosed in cows were reproductive and udder diseases. Calves suffered most often from diarrhea, omphalitis and pneumonia. The directly disease-related costs per cow-year on average amounted to CHF 139.44 and CHF 4.18 per calf. For prevention, farmers spent on average CHF 10.18 per cow-year. Results from the laboratory analyses indicate that in 68.1% of the farms antibodies against Leptospira hardjo and in 61.9% against Coxiella burnetii were detected. In 8.0% of the farms antibodies against Mycobacterium paratuberculosis were found. Antibodies against BVD virus was present in 99.4% of the farms. Cows from 63.7% farms were infected with gastrointestinal strongylids. Veterinary assistance was required on average 1.96 times per cow-year. In almost all reproductive and puerperal disease cases a veterinarian was consulted while lameness in the majority of cases was treated by the owner. The veterinary profession was hardly ever involved in disease prevention.

[Systems for monitoring animal health in Switzerland]. / Systeme zur Erfassung der Tiergesundheit in der Schweiz.

Due to the changing conditions of animal production in Switzerland the demand for scientifically based animal health information has increased during the last years. It has become a central element in animal health policy making. National animal health surveillance systems include methods for data collection, analyses, interpretation and information distribution. The current Swiss surveillance systems are presented. In the future, these systems should be more integrated in order to make better use of the available data. The project "Systems for the recording of animal health in Switzerland" (SysET) is a proposal how a comprehensive animal data base could be developed.

[Diseases and culling of Swiss dairy cows. 2. Culling and relation between diseases and milk production parameters]. / Krankheiten und Abgänge bei schweizerischen Milchkühen. 2. Abgänge und Beziehungen zwischen Krankheiten und Milchleistungsparametern.

During three years (1982 to 1984) data were collected concerning diseases and reasons for culling in 612 dairy farms with Brown Swiss, Simmental and Black and White cattle. The frequency of culling increases in all three breeds with increasing age, from 20% at the first lactation up to 33% from the 4th lactation on. The main reasons for disposal are insufficient production, reproductive problems or udder diseases. After treatment for reproductive problems, mastitis or acetonemia, the risk for culling within the same lactation period is increased. Reproductive problems (no heat symptoms, repeat breeder, ovarian cysts) and acetonemia increase with increasing milk production in all three breeds. In cows with high 100-day-performance they are also more frequent. The occurrence of acute mastitis shows no general trend with increasing milk production or with high 100-day-performance. No systematic relationship is found between reproductive disorders or acute mastitis and persistency of milk production. On the other hand, acetonemia is somewhat more frequent in cows showing higher persistency.