Comparing the demonstration of freedom from Trichinella infection of domestic pigs by traditional and risk-based surveillance.

Traditionally, the routine artificial digestion test is applied to assess the presence of Trichinella larvae in pigs. However, this diagnostic method has a low sensitivity compared to serological tests. The results from artificial digestion tests in Switzerland were evaluated over a time period of 15 years to determine by when freedom from infection based on these data could be confirmed. Freedom was defined as a 95% probability that the prevalence of infection was below 0.0001%. Freedom was demonstrated after 12 years at the latest. A new risk-based surveillance approach was then developed based on serology. Risk-based surveillance was also assessed over 15 years, starting in 2010. It was shown that by using this design, the sample size could be reduced by at least a factor of 4 when compared with the traditional testing regimen, without lowering the level of confidence in the Trichinella-free status of the pig population.

Assessment of exposure to bovine spongiform encephalopathy in a hypothetical country.

The authors present a basic quantitative spreadsheet model to evaluate the risk of bovine spongiform encephalopathy (BSE) within a national setting. The model is based on information from BSE risk assessments undertaken in Latin American countries. The analysis focuses on the level of regulatory implementation and its impact over different time periods and estimates the potential impact if one BSE-infected animal is introduced into the production cycle. The information is consolidated so that the results of the evaluation can be presented for a hypothetical country, 'Country X'. Evaluating the BSE cycle within a country may help in making decisions on where preventive or control measures should be placed and/or enforced. Such an evaluation may also be used as the exposure assessment of a risk assessment, recommended by the World Organisation for Animal Health to determine the BSE risk status of a given country.

Validation of a Western Blot for the detection of anti-Trichinella spp. antibodies in domestic pigs.

Trichinellosis is a zoonotic disease in humans caused by Trichinella spp. According to international regulations and guidelines, serological surveillance can be used to demonstrate the absence of Trichinella spp. in a defined domestic pig population. Most enzyme-linked immunosorbent assay (ELISA) tests presently available do not yield 100% specificity, and therefore, a complementary test is needed to confirm the diagnosis of any initial ELISA seropositivity. The goal of the present study was to evaluate the sensitivity and specificity of a Western Blot assay based on somatic Trichinella spiralis muscle stage (L1) antigen using Bayesian modeling techniques. A total of 295 meat juice and serum samples from pigs negative for Trichinella larvae by artificial digestion, including 74 potentially cross-reactive sera of pigs with other nematode infections, and 93 meat juice samples from pigs infected with Trichinella larvae were included in the study. The diagnostic sensitivity and specificity of the Western Blot were ranged from 95.8% to 96.0% and from 99.5% to 99.6%, respectively. A sensitivity analysis showed that the model outcomes were hardly influenced by changes in the prior distributions, providing a high confidence in the outcomes of the models. This validation study demonstrated that the Western Blot is a suitable method to confirm samples that reacted positively in an initial ELISA.

Risk assessment and surveillance for bovine spongiform encephalopathy.

The national risk of bovine spongiform encephalopathy (BSE) has not been assessed by many countries, and many countries are conducting little or no BSE surveillance. National measures implemented, including import restrictions, surveillance systems, and sanitary controls, should be based on actual BSE risk. Thus, as a first step, the national BSE status must be determined, particularly through assessment of the national risk. The World Organisation for Animal Health (OIE) provides recommendations for surveillance and risk assessment of BSE, which are considered the international standard by the World Trade Organization (WTO). This document describes the variables for determination of BSE status and gives guidance on specific options and practical considerations for meeting the BSE surveillance and risk assessment recommendations of the OIE.

Risk management of transmissible spongiform encephalopathies in Europe.

Bovine spongiform encephalopathy (BSE) was first described in the United Kingdom (UK) in November 1986. After the introduction of an active surveillance system, most countries in Europe have reported BSE cases in the cattle population. This indicates that the use of active surveillance in addition to passive surveillance is important to assess the true BSE status in a country. Scrapie, a transmissible spongiform encephalopathy (TSE) in sheep and goats, has been reported in countries throughout the world with a few notable exceptions. Concern was expressed that BSE could have been introduced into sheep and goats. Currently, distinguishing between scrapie and BSE in small ruminants is only possible through lengthy experiments in mice. Preliminary results of active surveillance, introduced in 2002, show that significant under-reporting occurred. The history of BSE in cattle shows that risk assessments concerning the risk in a given country were often ignored and subsequent risk management decisions were inaccurate, i.e. although the risk was probable, no measures were taken in terms of either animal or human health. Furthermore, the effect of the measures taken was often overestimated and these had to be amended several times. The most important action to prevent new cases of TSEs occurring is by banning the feeding meat-and-bone meal (MBM) to ruminants. Further measures to be considered are the exclusion of specified risk material and carcasses from rendering, the process parameters for rendering of animal waste and the prevention of cross-contamination of feed with MBM. The most important measures to protect the consumer are the ban on specified risk material, such as brain and spinal cord, which may contain particularly high concentrations of the BSE agent, and the ban on mechanically recovered meat. The most important measures taken in Europe and the scientific background thereof are described and discussed.

The federal system of Veterinary Services in Switzerland.

The Veterinary Service is described in the context of the federal state system in Switzerland. The Federal Veterinary Office (FVO) plays a leading role in this Service. Apart from its responsibility for legislation, the most important task of the FVO is the dissemination of information throughout Switzerland. The responsibility for ensuring that the laws are implemented lies with the 26 cantons. Veterinary public health is a key function of the Veterinary Service, where the core focus is on the implementation of the 'stable to table' concept. Animal protection is also an important function. A certified Veterinary Service requires a high-quality system based on professionalism, objectivity and evaluation. In this paper, the various strengths and weaknesses of the system in Switzerland are discussed and the disadvantages are analysed in depth.

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.

[Ten years of BSE in Switzerland. The development of an extraordinary disease]. / 10 Jahre BSE in der Schweiz. Der Verlauf einer aussergewöhnlichen Krankheit.

The first case of bovine spongiform encephalopathy (BSE) in Switzerland was diagnosed in November 1990. BSE is--in particular considering its eradication--different from many other livestock diseases. Strict disease control measures were taken from the very beginning by the Swiss authorities in order to protect public as well as animal health. In addition, BSE has stimulated enormous media interest and public concern. The occurrence of the born after the ban (BAB) cases, increasing questions about the zoonotic potential of the disease and trade restrictions against Switzerland led to the "BSE-crisis". In 1999, Switzerland internationally took a leading role in the surveillance of BSE by active investigation of targeted risk population.

Bovine spongiform encephalopathy in Switzerland--the past and the present.

The first case of bovine spongiform encephalopathy (BSE) in Switzerland was diagnosed in November 1990, although the risk factors identified in the United Kingdom were not all present in Switzerland. At 29 December 1998, a total of 282 BSE cases (all animals born in Switzerland), had been recorded. The number of cases is declining, with fourteen cases diagnosed in 1998 (at 29 December 1998). The measures taken are effective. However, the potential weakness in current activities that allow the disease to exist are being evaluated. Further measures to avoid even minimal risk for human and animal health will be taken if required. Experience gained from the past indicates that it is necessary to review the situation constantly and to inform the public and professionals regularly and in a transparent manner.

[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.

[182 offspring of cows with bovine spongiform encephalopathy (BSE) in Switzerland. 1. Clinical findings]. / Untersuchungen an 182 Nachkommen von an boviner spongiformer Enzephalopathie (BSE) erkrankten Kühen in der Schweiz. Teil 1: Klinische Befunde.

This study involved 182 calves, heifers and cows that were the first generation progeny of cows with bovine spongiform encephalopathy (BSE). All animals underwent clinical and neurological examinations. Blood, milk, urine, ruminal fluid and cerebrospinal fluid samples were examined. Each cow underwent a specific examination for BSE which included assessment of behaviour, sensitivity and locomotion. This examination was performed twice, and there was very good agreement between the results. The most common symptom was nervousness (14 animals). In the first examination, 68 animals were mildly to moderately sensitive to touching of the head, 44 animals were hypersensitive to a halogen light and 35 animals were hypersensitive to a camera flash. Twenty-four animals reacted by kicking when the hindlimbs were touched with a broom. None of the animals had disturbances in locomotion. Based on the interpretation of all findings and the comparison of the results of the first and second examinations, 173 animals were diagnosed as free of BSE. In 9 animals, the disease could not be ruled out; however, it could not be confirmed in any of them. Histological and immunohistochemical examinations of the brain of all animals were negative for BSE (see Part 2 of the study for details). The results of this study indicate that abnormal clinical findings may occur in clinically healthy cattle. However, none of the progeny of cows with BSE exhibited clinical signs typical of BSE, such as disturbances in behaviour; sensitivity and locomotion.

The production system and disease incidence in a national random longitudinal study of Swiss dairy herds.

A prospective longitudinal observational study based on a stratified random sample of 113 Swiss dairy farms was conducted between April 1993 and July 1994 with the following objectives: (i) to provide statistically valid estimates of disease frequency in the Swiss dairy cow population, and (ii) to evaluate the feasibility and quality of an intensive farm-based data recording system. During the 15-month study period, farmers were asked to record every health and management event related to their cattle herd. This information was mailed back to the study centre at fortnightly intervals. Additionally, farms were visited regularly to verify received data and to discuss specific problems. During these farm visits, management data were recorded using questionnaires. A complete data set of individual animal events with a total observation time of about 1740 cow-years and 275 calf-years was collected and disease-incidence measures were calculated. The most frequent events were reproductive disorders and udder diseases, followed by lameness and metabolic disorders. Experience with the data collection technique used in this study suggests that a farm-based system is effective and reliable, as long as good contact with the farmers is maintained, and incentives to stimulate their motivation are provided.

[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.

[Clinical examination upon suspicion of bovine spongiform encephalopathy (BSE)]. / Klinischer Untersuchungsgang bei Verdacht auf bovine spongiforme Enzephalopathie (BSE).

The most important clinical signs of BSE are hypersensitivity to manipulations of the head and neck and disturbances in behaviour and locomotion. Diagnostic procedures include thorough clinical and neurological examination with emphasis on the assessment of behaviour, locomotion and sensitivity. The findings have to be interpreted carefully and depending on the diagnosis, national animal health regulations must be followed.

Research and technological developments required for more rapid control and eradication of foot and mouth disease.

Foot and mouth disease (FMD) is the major disease barrier to international trade in animals and animal products. Countries free of the disease take severe measures to exclude the virus, to avoid the potentially devastating consequences of an outbreak, particularly for the animal export trade. Consequently, FMD-free countries either refuse to trade with sporadically or endemically infected countries, or else apply stringent and often expensive safeguards before agreeing to import animals or animal products. Technological advances can assist countries which are free of FMD to maintain this status. Such advances also aid countries in which the disease is sporadic or endemic, by accelerating the progress of control and eradication programmes. The authors review recent advances in tests for the diagnosis of FMD, in addition to advances in surveillance, vaccinology and information technology, i.e. computing and networking. Furthermore, the authors examine the application of these advances to improve programmes for the control and eradication of FMD, and identify the requirements for further research into the disease.

[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.

Surveillance of contagious bovine pleuropneumonia in Switzerland.

An active surveillance system for contagious bovine pleuropneumonia (CBPP) has been established in Switzerland. The system is based on the detection of typical gross pathological lesions in the lungs of slaughtered cattle, followed by microbiological analysis of the sampled organs and sero-epidemiological investigation of the herd of origin for each suspect case. The programme was tested over six months. The prevalence of lung lesions detected in carcasses during this period in the 108 participating abattoirs was 0.04%, but Mycoplasma mycoides subsp. mycoides SC was not isolated from any of these organs. On the basis of the results presented, there is no evidence of CBPP in Switzerland. The surveillance programme will continue, however, in order to document the situation and eventually obtain a disease-free status in accordance with international standards.

The relative density of CD44-positive porcine monocytic cell populations varies between isolations and upon culture and influences susceptibility to infection by African swine fever virus.

African swine fever (ASF) virus has been reported to infect cells of the monocyte family, probably macrophage-like cells, but there is variation in the apparent susceptibility of these cells. We have demonstrated that the phenotype and activity of porcine monocytic cells varies between different isolations and also upon culture. The variation during culture is dependent upon the phenotype of the cells at the time of isolation. As for the susceptibility of porcine monocytes/macrophages to infection by ASF virus, it was seen that this could be related to the variation in cell phenotype and activity. The susceptibility was determined by the relative density of particular subpopulations of cells present. Whilst inflammatory macrophages did not have an apparent role to play, phagocytic activity was influential. Furthermore, the expression of CD44 and the DH59 myeloid cell marker was important, whereas the relevance of MHC Class II expression was variable. Overall, it was concluded that susceptibility to infection required that a culture be dominated by CD44-positive cells which were non-inflammatory, of low phagocytic activity, and characterizable as being of the myeloid (DH59-positive) lineage.