The Importance of Hazard Analysis by Critical Control Point for Effective Pathogen Control in Animal Feed: Assessment of Salmonella Control in Feed Production in Sweden, 1982-2005

This study is the first to show that Hazard Analysis by Critical Control Point (HACCP)-based monitoring can be an effective tool for ensuring Salmonella-safe feed, by virtually eliminating feedborne Salmonella infection even in broiler production. Data from the control of Salmonella in feed and food animal production during 1982-2005, showed that conventional endpoint testing in feed mills did not ensure a Salmonella-safe feed, and in one feed mill failed to detect Salmonella contamination, resulting in the feed infecting 80 out of 197 (40.6%) recipient broiler flocks. Following implementation in 1991 of a HACCP-based control in feed mills, the annual number of samples tested at specified critical control points during a 15-year period increased from ∼4400 to 10,000, while the proportion of Salmonella-contaminated samples decreased from 2.0% to 0.3%. Thus, introduction of HACCP was followed by a dramatic decrease, from 40 to <5, in the annual number of Salmonella-infected broiler flocks identified by preslaughter monitoring. Incidence has generally remained at that low level, despite production since 1980 increasing from 39 to 112 million chickens per year. Feed mills start using soymeal with an unsafe Salmonella status and possibly with a suboptimal HACCP control, increased their level of Salmonella-contaminated HACCP samples, and their feed subsequently infected 78 swine-producing herds. The results also show that the HACCP concept can be an effective tool to supply feed mills with Salmonella-safe feed ingredients as demonstrated for a soybean crushing plant, which produced Salmonella-safe soymeal over a 19-year period despite frequent (34%) and highly varied (92 different serovars) Salmonella contamination in samples from incoming soybean. Similar results are reported for a plant producing rapeseed meal. It is emphasized that the achievements described through use of the HACCP required interventions of relevant preventive biosecurity measures and corrective actions when the HACCP-based monitoring identified Salmonella contamination.

Successful Prevention of Antimicrobial Resistance in Animals-A Retrospective Country Case Study of Sweden

The misuse and overuse of antibiotics have resulted in an alarmingly high prevalence of antimicrobial resistance (AMR) in human and animal bacteria. European monitoring programmes show that AMR occurrence in food animals is lower in Sweden than in most other EU Member States and that the use of antibiotics for animals is among the lowest in Europe. In this retrospective country case study, we analysed published documents to identify factors contributing to this favourable situation. A fundamental factor identified was early insight into and sustained awareness of the risks of AMR and the need for the prudent use of antibiotics. Early and continuous access to data on antibiotic use and AMR made it possible to focus activities on areas of concern. Another factor identified was the long-term control and eradication of infectious animal diseases, including coordinated activities against endemic diseases, which reduced the need to use antibiotics. Structures and strategies for that purpose established at the national level have since proven useful in counteracting AMR as an integral part of disease prevention and control, guided by a "prevention is better than cure" approach. A third factor identified was consensus among stakeholders on the need to address AMR and their cooperation in the design and implementation of measures.

Biosafety considerations and risk reduction strategy for a new veterinary faculty building and teaching hospital in Sweden

Introduction

This paper describes a hazard- and risk-based strategy and recommendations on relevant biosafety levels in facility design of a new veterinary faculty building including a veterinary medical teaching hospital. Both animal and human health were considered.

Materials and methods

Agents listed in the regulatory frameworks on animal and human health were identified as the main potential hazards. Suggestions on biosafety level and facility design were based on the official risk grouping of those agents, the associated risk management procedures, and biosafety experiences from previous faculty buildings.

Results and Discussion

It was suggested that VHC should not be designed for work with agents requiring facilities at biosafety levels 3 and 4, and that actions in cases of accidental exposure to notifiable infections should follow the regulatory requirements. Facilities requiring biosafety level 2 were identified from risk scenarios and transmission routes.

Experiences from the first five years of operation revealed good prevention of spread of infection from patients in isolation facilities and successful elimination of Salmonella and MRSA from the large animal clinic.

Conclusion

In order to avoid costly construction mistakes, an overall biosafety strategy should be formulated and used as guidance for architects and other relevant stakeholders designing facilities for the animal health sector. Regulatory requirements on infectious diseases must be complied with.

Occurrence of Salmonella spp.: a comparison between indoor and outdoor housing of broilers and laying hens

BACKGROUND

Outdoor production of poultry is rapidly increasing, which could be associated with increased risks for exposure to different environmental sources of Salmonella. We report a comparison on the occurrence of Salmonella during 2007-2015 in broilers and laying hens in outdoor and indoor production subjected to the same requirements for the prevention and control of Salmonella as applied in Sweden.

RESULTS

Our results give no indication that, during the period studied, the exposure to Salmonella in outdoor poultry production was higher than in the indoor production. The annual incidence of Salmonella infected flocks in outdoor production remained at a very low and at a similar level as for indoor production. For laying hens the annual proportion of birds in test positive flocks ranged from 0 to 1.3% for indoor production from 0 to 2.0% for outdoor production. For broilers the proportion of Salmonella infected flocks (2013-2015) was 0.16% for indoor, and 0% in outdoor production. The difference was not statistically significant and was further reduced when flocks infected due to vertical transmission or from a hatchery source were excluded. It should, however, be considered that the number of outdoor flocks included in this evaluation is very small and continuous evaluation is needed.

CONCLUSIONS

New animal production systems, including those driven by consumer and welfare demands, may be associated with a higher risk for the exposure of potential pathogens to food animals and possibly also subsequent outbreaks of food borne infections. In this study no increase in the risk for exposure of flocks to Salmonella in outdoor poultry production was found. The situation may well change and the possibility of Salmonella contamination in outdoor poultry production requires continuous attention.

Prevention of Salmonella contamination of finished soybean meal used for animal feed by a Norwegian production plant despite frequent Salmonella contamination of raw soy beans, 1994-2012

BACKGROUND

Salmonella contaminated animal feed is a major source for introducing Salmonella into the animal derived food chain. Because soybeans frequently are contaminated with Salmonella, soybean meal used as animal feed material, a by-product of a "crushing plant" which produces oil from soybeans, can be important source of Salmonella in the animal feed.

RESULTS

During the 19-year period, 34% of samples collected during unloading of ships delivering soybeans yielded Salmonella; the proportion of samples from ships that yielded Salmonella varied from 12-62% each year. Dust samples from all shiploads from South America yielded Salmonella. In total 94 serovars of Salmonella were isolated, including nine (90%) of the EU 2012 top ten serovars isolated from clinical cases of salmonellosis in humans, including major animal pathogenic serovars like Spp. Typhimurium and Enteritidis.

CONCLUSIONS

This study shows that a HAACP-based control program in a soybean crushing plant can produce Salmonella free soybean meal despite frequent Salmonella contamination of raw soybeans. That approach is suggested as an effective way to minimize the risk of Salmonella exposure of the animal feed mills and contamination of the subsequent animal feed chain.

Estimation of costs for control of Salmonella in high-risk feed materials and compound feed

INTRODUCTION

Feed is a potential and major source for introducing Salmonella into the animal-derived food chain. This is given special attention in the European Union (EU) efforts to minimize human food-borne Salmonella infections from animal-derived food. The objective of this study was to estimate the total extra cost for preventing Salmonella contamination of feed above those measures required to produce commercial feed according to EU regulation (EC) No 183/2005. The study was carried out in Sweden, a country where Salmonella infections in food-producing animals from feed have largely been eliminated.

METHODS

On the initiative and leadership of the competent authority, the different steps of feed production associated with control of Salmonella contamination were identified. Representatives for the major feed producers operating in the Swedish market then independently estimated the annual mean costs during the years 2009 and 2010. The feed producers had no known incentives to underestimate the costs.

RESULTS AND DISCUSSION

The total cost for achieving a Salmonella-safe compound feed, when such a control is established, was estimated at 1.8-2.3 € per tonne of feed. Of that cost, 25% relates to the prevention of Salmonella contaminated high-risk vegetable feed materials (mainly soybean meal and rapeseed meal) from entering feed mills, and 75% for measures within the feed mills. Based on the feed formulations applied, those costs in relation to the farmers' 2012 price for compound feed were almost equal for broilers and dairy cows (0.7%). Due to less use of protein concentrate to fatten pigs, the costs were lower (0.6%). These limited costs suggest that previous recommendations to enforce a Salmonella-negative policy for animal feed are realistic and economically feasible to prevent a dissemination of the pathogen to animal herds, their environment, and potentially to human food products.

Scientific and technical factors affecting the setting of Salmonella criteria for raw poultry: a global perspective

Concerns about foodborne salmonellosis have led many countries to introduce microbiological criteria for certain food products. If such criteria are not well-grounded in science, they could be an unjustified obstacle to trade. Raw poultry products are an important part of the global food market. Import and export ambiguities and regulatory confusion resulting from different Salmonella requirements were the impetus for convening an international group of scientific experts from 16 countries to discuss the scientific and technical issues that affect the setting of a microbiological criterion for Salmonella contamination of raw chicken. A particular concern for the group was the use of criteria implying a zero tolerance for Salmonella and suggesting complete absence of the pathogen. The notion can be interpreted differently by various stakeholders and was considered inappropriate because there is neither an effective means of eliminating Salmonella from raw poultry nor any practical method for verifying its absence. Therefore, it may be more useful at present to set food safety metrics that involve reductions in hazard levels. Such terms as "zero tolerance" or "absence of a microbe" in relation to raw poultry should be avoided unless defined and explained by international agreement. Risk assessment provides a more meaningful approach than a zero tolerance philosophy, and new metrics, such as performance objectives that are linked to human health outcomes, should be utilized throughout the food chain to help define risk and identify ways to reduce adverse effects on public health.

An assessment of soybeans and other vegetable proteins as source of Salmonella contamination in pig production

BACKGROUND

The impact of salmonella contaminated feed ingredients on the risk for spreading salmonella to pigs was assessed in response to two incidences when salmonella was spread by feed from two feed mills to 78 swine producing herds.

METHODS

The assessment was based on results from the salmonella surveillance of feed ingredients before introduction to feed mills and from HACCP--based surveillance of the feed mills. Results from the mills of the Company (A) that produced the salmonella contaminated feed, were by the Chi. Square test compared to the results from all the other (B - E) feed producers registered in Sweden. Isolated serovars were compared to serovars from human cases of salmonellosis.

RESULTS

Salmonella (28 serovars) was frequently isolated from imported consignments of soybean meal (14.6%) and rape seed meal (10.0%). Company A largely imported soybean meal from crushing plants with a history of unknown or frequent salmonella contamination. The risk for consignments of vegetable proteins to be salmonella contaminated was 2.4 times (P < 0.0006) larger for A when compared to the mills of the other companies which largely were supplied by soybean meal from a crushing plant with a low risk for salmonella contamination. Also the level of feed mill contamination of salmonella was higher for feed mills belonging to Company A in comparison to the other companies before and also after heat treatment. Four (10.5%) of the 38 serovars isolated from feed ingredients (28) and feed mills (10) were on the EU 2007 top ten list of human cases of salmonellosis and all but eight (78.9%) on a 12 year list (1997-2008) of cases of human salmonellosis in Sweden.

CONCLUSIONS

Salmonella contaminated feed ingredients are an important source for introducing salmonella into the feed and food chain. Effective HACCP-based control and associated corrective actions are required to prevent salmonella contamination of feed. Efforts should be taken to prevent salmonella contamination already at the crushing plants. This is challenge for the EU - feed industry due to the fact that 98% of the use of soybean/meal, an essential feed ingredient, is imported from crushing plants of third countries usually with an unknown salmonella status.

Low occurrence of Clostridium difficile in retail ground meat in Sweden

This pilot study was conducted to evaluate the occurrence of Clostridium difficile in samples of ground meat in Sweden. From April to September 2008, 82 meat samples were collected from randomly selected retail shops in Uppsala County (central Sweden). C. difficile was isolated from 2 (2.4%; both ground beef) of the 82 meat samples. No C. difficile was detected in pork, hamburger, sheep, poultry, or other type of meat samples. The two C. difficile isolates produced both toxin A and toxin B. These findings indicate that C. difficile might be present in ground meat samples in Sweden. However, further studies are necessary to confirm these preliminary data and to elucidate the public health significance of meat contamination by C. difficile in Sweden.

Antimicrobial resistance in Scandinavia after ban of antimicrobial growth promoters

The banned use of antimicrobial growth promoters resulted in a considerably decreased use of antimicrobials in food animal production in Sweden (65%), Denmark (47%), Norway (40%) and Finland (27%). The current prevalence of antimicrobial resistance in animal bacterial populations is also considerably lower than in some other countries in the EU. In the swine production, no or limited effect was found in the finisher production (>25 to 30 kg). Temporary negative effects occurred during the post weaning period (7-30 kg). In Denmark, the cost of production from birth to slaughter per pig produced increased by approximately 1.0 euro with a high variability between pig producers. In the broiler production the termination had no significant negative effect on animal health and welfare or on production economy.

Salmonella contamination: a significant challenge to the global marketing of animal food products

Salmonellosis is the most common food-borne bacterial disease in the world. Salmonella is a significant pathogen for food-producing animals and these animals are the primary source of salmonellosis. It is estimated that herd prevalence varies between 0% and 90%, depending on the animal species and region. The pathogen is spread by trade in animals and non-heated animal food products. The emergence of strains that are resistant to antimicrobials, often as a result of antimicrobial usage in animals, is a public health hazard of great concern. It is increasingly accepted that the prevalence of Salmonella in animal production must be decreased and, in the European Union, plans to achieve this are currently being implemented. In this paper, the authors propose various risk mitigation strategies. Successful control must focus on a range of preventive actions because there is no simple 'silver bullet' solution to reduce Salmonella contamination. The authors conclude that the key to controlling Salmonella is to follow the general rules that have been successfully applied to other infectious diseases.

Usage of veterinary therapeutic antimicrobials in Denmark, Norway and Sweden following termination of antimicrobial growth promoter use

Antimicrobial growth promoters (AGPs) were phased out in Denmark, Norway and Sweden in 1998-1999, 1995 and 1986, respectively. The annual usage of therapeutic antimicrobials in animals in Denmark almost doubled during the period when AGPs were phased out (1988-1999) and in the subsequent 2 years. The increase was mainly due to an increased consumption of therapeutic antimicrobials in weaning pigs. The annual increase in usage of therapeutic antimicrobials and the annual increase in numbers of slaughter-swine produced in Denmark correlates well, except for 1999 when AGP use was discontinued in weaning pigs, and the following year. In Norway, the usage of therapeutic antimicrobials in animals decreased by 39% from 1995 to 2000. During 2001-2003 the annual usage remained at the 2000-level. The annual numbers of slaughter-swine produced in Norway increased gradually by 10% after the AGP discontinuation (from 1995 to 2003). In Sweden, the usage of therapeutic antimicrobials in animals increased by 21% the first 2 years subsequent to the AGP ban (1986-1988), remained then constant until 1994; from 1994 to 2003 this usage declined by 47%. The initial increase was caused by increased use in broilers and in weaning piglets. The amounts used in animals in Sweden in 2003 were half of the amounts used in 1994. The annual numbers of slaughter-swine produced in Sweden declined gradually by 16% in the study period, although fluctuating. In Denmark, Norway and Sweden the number of dairy cattle and beef cattle declined only slightly in the various study periods while numbers of broilers produced increased notably, especially in Norway and Sweden. Following the termination of AGPs the total usage of antimicrobials (AGPs and therapeutic antimicrobials) in animals in Denmark declined 36% (from 1996 to 2003): in Norway this figure was 45% (from 1995 to 2003). In Sweden, the total usage of antimicrobials in animals in 2003 amounted to only one third of the amounts used in 1984 (decreased from 51 to 16 tonnes). Termination of AGPs was only a temporary risk factor for increased usage of therapeutic antimicrobials in food-animals in Sweden and Denmark; however, an exception might be usage in weaning piglets in Denmark. Furthermore, the discontinuation of AGP use has decreased the overall annual usage of antimicrobials in animals in Denmark, Norway and Sweden considerably.

The Swedish experience of the 1986 year ban of antimicrobial growth promoters, with special reference to animal health, disease prevention, productivity, and usage of antimicrobials

In Sweden the use of antimicrobial growth promoters (AMGP) was banned in 1986. The experiences gained from that ban are presented. In production of slaughter pigs, specialized beef, and turkeys, no negative clinical effects were reported as a consequence of the ban. In broiler chicken production, expected problems with necrotic enteritis were prevented by a continuous use of antibiotics, largely to the same extent during the first 2 years after the ban. Following the implementation of results from experimental activities during that period, the general usage of antimicrobials could be stopped and expected problems with outbreaks of necrotic enteritis was prevented. In piglet production, significant clinical problems emerged that created a demand for antibiotic-medicated feed at therapeutic dosages. During the subsequent 4-year period, the use of antibiotics increased, involving up to 75% of the pigs. Thereafter, the use of antibiotics decreased because of improved management, and could be halved in 1993 followed by a gradual further decrease supported by the addition of zinc oxide to the feed. In 1998, compared to 1994, the total use of zinc decreased by 90%. In 1998/1999, only 5% of weaning piglet producing herds used antibiotic medicated feed and 17% used zinc. The AMGP ban has shown that under good production conditions it is possible to reach good and competitive production results for the rearing of poultry, calves, and pigs without the continuous use of AMGP. As a result of the ban and a focus on disease prevention and correct use of antimicrobials, the total use of antibacterial drugs to animals in Sweden decreased by approximately 55% during the last 13-year period, and a relatively low prevalence of antimicrobial resistance has been maintained.

The experience of reducing antibiotics used in animal production in the Nordic countries

The Nordic countries (Denmark, Finland, Norway and Sweden) have a long tradition of infectious disease control in animal production. Special attention has also been paid to the use of antibiotics. This has resulted in a relatively low use of antibiotics and also relatively favourable status of antibiotic resistance. The current situation, interventions and achievements are summarised with special reference to Sweden which was probably the first country where stringent control and prudent use of antibiotics was put into practice. The use of antibiotics for growth-promoting purposes is highlighted.

The control of microbial diseases in animals: alternatives to the use of antibiotics

In animal husbandry the control and prevention of infectious diseases is of basic economic importance. The introduction of antibiotics to treat bacterial infections almost 50 years ago led to a dramatic improvement in animal production. The emergence of antibiotic resistant strains demonstrates that the treatment of bacterial infections can not rely on the use of antibiotics without some critical consideration. Special attention has been paid to the use of antibiotics in animals including antimicrobial growth promoters because these can contribute to the problems with antibiotic resistance in humans. This has strongly emphasized the need to introduce disease preventive methods. A theory and methods for the prevention of diseases is presented that is based upon the effect on the target animal population of microbial exposure, defence and immunity to infections and combinations of these. It is emphasized that antibiotics should be an integral part of other disease preventive methods and used only when other methods have failed. They should not be included in the first line of action.

Vaccination and eradication programme against Aujeszky's disease in five Swedish pig herds with special reference to herd owner attitudes

A vaccination eradication programme against Aujeszky's disease (AD), based on the use of gE-negative killed vaccine, was carried out between 1987 and 1992 in 5 Swedish weaner pig producing or farrow-to-finish herds, with 63 to 398 breeding animals. All breeding animals were tested at the start and the end of the programme. Seroprevalence to Aujeszky's disease virus (ADV) ranged between 47% and 100% in the herds at the first test. During the programme, all breeding animals were vaccinated simultaneously every 4 months and ADV-free replacement animals were vaccinated shortly after arrival and boostered within a month. In one herd only, a limited number of fatteners were vaccinated. The herds were declared free (gE-negative) 12 to 53 months after the start of the programme. When all seropositive breeding animals had been culled, the programme ended after 2 negative tests of the breeding animals. Seroconversion was limited in all herds but one, where initially no isolation unit was available for replacement animals. The attitude of the herd owners towards the programme and the special conditions prevailing in the herds are discussed. It is suggested that vaccination may promote risk behaviour of herd managers.

Patterns of seroconversion to Aujeszky's disease virus in unvaccinated chronically infected Swedish weaner pig-producing herds

This study was carried out in nine unvaccinated Swedish weaner pig-producing herds, ranging in size from 20 to 134 breeding animals, which had experienced a previous outbreak of Aujeszky's disease (AD) and in which seropositive sows were still present. The objective was to quantify the seroconversion rate to Aujeszky's disease virus (ADV) in breeding animals and to find out whether unvaccinated herds could become free from ADV by using only seronegative animals for replacement. Serum samples were initially obtained from all adult pigs in the herds. Animals testing negative, as well as replacement animals, were subsequently tested every second or third month and the herds were followed for 10-28 months. The herd owners were advised to keep seropositive and seronegative animals separate whenever possible and to implement sanitary measures against the reintroduction of the virus into the herds. All herds experienced long consecutive periods (> or = 4 months, median 9 months) without seroconversion. Three herds became free from ADV during the serological study; in two of these herds no seroconversion was observed. In those seven herds where seroconversion occurred, between 9 and 86% of the susceptible pigs became infected. The reinfection was indicative of the reactivation of latent virus in all herds but two, where the reintroduction of the virus was most likely. The pattern of seroconversion was either sporadic, involving not more than three animals at a time, or epidemic, involving a large proportion of the susceptible animals in the herd. Severe clinical outbreaks hit the two largest herds and these only became ADV-free after the conclusion of the study when vaccine was used, which reduced the incidence of seroconversion to zero. The results from the present study show that it is possible for smaller herds to achieve freedom from ADV without any radical control methods, provided that only ADV-free replacement animals are used and the virus is not reintroduced. Moreover, the finding that long periods can elapse without transmission suggests that when infection is discovered in a herd, the risk of massive spread is not necessarily imminent.

Vaccination and eradication programme against Aujeszky's disease in five Swedish pig herds with special reference to herd owner attitudes

A vaccination eradication programme against Aujeszky's disease (AD), based on the use of gE-negative killed vaccine, was carried out between 1987 and 1992 in 5 Swedish weaner pig producing or farrow-to-finish herds, with 63 to 398 breeding animals. All breeding animals were tested at the start and the end of the programme. Seroprevalence to Aujeszky's disease virus (ADV) ranged between 47% and 100% in the herds at the first test. During the programme, all breeding animals were vaccinated simultaneously every 4 months and ADV-free replacement animals were vaccinated shortly after arrival and boostered within a month. In one herd only, a limited number of fatteners were vaccinated. The herds were declared free (gE-negative) 12 to 53 months after the start of the programme. When all seropositive breeding animals had been culled, the programme ended after 2 negative tests of the breeding animals. Seroconversion was limited in all herds but one, where initially no isolation unit was available for replacement animals. The attitude of the herd owners towards the programme and the special conditions prevailing in the herds are discussed. It is suggested that vaccination may promote risk behaviour of herd managers.

Eradication of Aujeszky's disease virus from a Swedish pig herd using gI-/TK-vaccine

An attenuated glycoprotein I-negative (gI-)/thymidine kinase-negative (TK-) constructed vaccine was used to eradicate Aujeszky's disease virus from a large farrow-to-finish herd in Sweden. The herd had had problems every year for seven years and two attempts to eradicate the virus without vaccination had failed. At the start of the vaccination programme 86 per cent of the 396 breeding animals were seropositive to the virus. In spite of evidence of virus circulation in the fattening units, no fatteners were vaccinated. The breeding stock was vaccinated every four months and monitored serologically. Seropositive sows and boars were culled at an economic rate. During the programme, four breeding animals seroconverted to gI. Another seven animals which seroconverted to gI were suspected to have been infected shortly before the first test and vaccination. When all the seropositive breeding animals had been culled, the fattening units were sampled and no seropositive animals were found. The herd was declared gI-negative 39 months after the start of the programme. Monitoring of the herd for another four years, until all the vaccinated animals had been culled, showed that the herd remained free from Aujeszky's disease virus.

Agricultural policy and social returns to eradication programs: the case of Aujeszky's disease in Sweden

Economic-welfare analysis of animal disease prevention programs frequently ignore the constraints of the agricultural policy environment. Prevention programs affect producers, consumers and the government. The policy environment to a large extent determines the magnitude as well as the distribution of benefits of the program among these groups. The Swedish hog industry has been exposed to three major policy changes during the 1990-1995 period. These scenarios involve various degrees of government intervention in the agricultural sector including internal market deregulation and EU-membership. Aujeszky's disease is a virus disease with swine as the natural infection reservoir. Piglets are the most fragile and an outbreak of the disease results in symptoms such as shaking, cramps and convulsions with an increase in the mortality rate. Slaughter hogs suffer from coughing, fever and reduce their feed consumption. During the last 20-25 years the incidence of Aujeszky's disease (AD) has been increasing in Sweden. In 1989 an eradication program was undertaken. A model is developed to analyze social benefits of an eradication program given variations in agricultural policy. The model refers to the specifics of the AD-program implemented in Sweden. The expected benefits of the program are evaluated using a welfare-economic analysis applying cost-benefit analysis. Total benefits of the program are evaluated across herd and size categories and different regions. Data concerning the frequency of the virus among various categories of herds prior to enacting the program were used (Wahlström et al., 1990). In addition, data from an agricultural insurance company were used to estimate the conditional probability of an outbreak given that the herd is infected. Biological and technical parameter values were collected from a variety of sources. The results of the analysis indicate that the program is economically viable given a social rate of discount in the range of 3-5% without considering non-monetary aspects such as animal ethics. A scenario where the Swedish agricultural sector is deregulated provides the maximum benefits of the program. Consumers obtain about 50% of the benefits excluding program costs. The deregulation scenario would correspond closely to a case where a reformed Common Agricultural Policy (CAP) is applied across member countries. In the current case where Sweden is a member of the EU, the benefits are reduced mainly due to lower prices of inputs and pork.

Control of Salmonella enteritidis in Sweden

The Swedish control of Salmonella, with special reference to Salmonella enteritidis, in poultry is described. The control is directed at all serotypes of Salmonella and imported grandparent chickens are controlled, which is considered to be the main reason why Sweden so far is not found to be involved in the worldwide spread of different phagetypes of S. enteritidis. However, this spread has initiated a more stringent control of Salmonella in layers as earlier existed in broilers. Since 1990, 90% of the layer flocks are voluntarily tested for Salmonella before slaughter by bacteriological examination of pooled faecal samples. If S. enteritidis is isolated the flock is destroyed. This test, and in addition two similar tests during the production are mandatory as of January 1st, 1994. The voluntary Salmonella control programme has also been extended to all of the layer parents and hatcheries since 1991. Only heat-treated feed is given to all layer chickens during the rearing period and its use is becoming gradually more common also during the production period. Since 1987, four layer flocks have been found to be infected by S. enteritidis phagetype 4 and one flock with phagetype 6. During 1970-1984, 90% of all flocks of broilers were voluntarily tested bacteriologically for Salmonella before slaughter, and since 1984 such a control is mandatory to all flocks. As a result of this and other controls, S. enteritidis has not been isolated from broilers since 1972. Based on a governmental regulation from 1961, introduced as a result of a large Salmonella epidemic in 1953, Sweden runs an active, official control of Salmonella (Wierup et al., 1992).(ABSTRACT TRUNCATED AT 250 WORDS)

Salmonella isolated from animals and feedstuffs in Sweden during 1983-1987

This survey describes the frequency of Salmonella in animals and feedstuffs isolated in Sweden 1983-1987. Since 1949 National Veterinary Institute (NVI) has published such reports every fifth year. During the period of this report 760 outbreaks of Salmonella were reported in animals. This includes both domestic and wild animals. The corresponding figure for the previous period was 1266 outbreaks. 56 different serovariants were reported, 17 of these were new to Sweden. In cattle and swine there were a decrease of outbreaks. In poultry 86 outbreaks were reported, compared with 220 outbreaks during the previous five-year period. Swedish feed producing plants are checked both voluntary and compulsory, for the presence of Salmonella in raw materials, scrape and dust samples and compound feed. During 1983-1987 a total of 236 strains at Salmonella were isolated. This is the lowest incidence found during the last 15 years. All consignments of feedstuffs of animal origin intended for import to Sweden has to be examined for the presence of Salmonella. During 1983-1987 8.6% of the consignments were positive for Salmonella and were thus not allowed to be used in Sweden.

Experience of a 10-year use of competitive exclusion treatment as part of the Salmonella control programme in Sweden

In Sweden, competitive exclusion (CE) treatment has been used since 1981 as a part of the national control programme for Salmonella. According to the programme all broiler flocks are tested for Salmonella before slaughter thus providing an evaluation of CE treatment. The CE culture used is mainly for the two consecutive flocks raised in a unit after a Salmonella-infected flock has been identified. During the period 1981-1990 Ce culture has been given to 179 flocks, involving 3.82 million chickens. Only one of the treated flocks was found to be Salmonella-positive. A special study during a period when Salmonella was spread by contaminated feed demonstrated that CE treatment was effective in controlling Salmonella under field conditions. A likely contributory factor is that the hatcheries in Sweden can be claimed to be Salmonella-free. In addition, the control programme and related action, have led to a very low incidence of Salmonella in broiler chickens. A nationwide study carried out in 1990 demonstrated that less than 1% of broiler chickens was contaminated with Salmonella after slaughter.

Salmonella isolated from animals and feedstuffs in Sweden during 1983-1987

This survey describes the frequency of Salmonella in animals and feedstuffs isolated in Sweden 1983-1987. Since 1949 National Veterinary Institute (NVI) has published such reports every fifth year. During the period of this report 760 outbreaks of Salmonella were reported in animals. This includes both domestic and wild animals. The corresponding figure for the previous period was 1266 outbreaks. 56 different serovariants were reported, 17 of these were new to Sweden. In cattle and swine there were a decrease of outbreaks. In poultry 86 outbreaks were reported, compared with 220 outbreaks during the previous five-year period. Swedish feed producing plants are checked both voluntary and compulsory, for the presence of Salmonella in raw materials, scrape and dust samples and compound feed. During 1983-1987 a total of 236 strains at Salmonella were isolated. This is the lowest incidence found during the last 15 years. All consignments of feedstuffs of animal origin intended for import to Sweden has to be examined for the presence of Salmonella. During 1983-1987 8.6% of the consignments were positive for Salmonella and were thus not allowed to be used in Sweden.

Vaccination and eradication programme against Aujeszky's disease in Sweden, based on a gI ELISA test

A killed gI-negative vaccine combined with a gI enzyme-linked immunosorbent assay (ELISA) test was used for the first time in Sweden in an attempt to eradicate Aujeszky's disease from a weaner pig producing herd. The herd had experienced three severe outbreaks of the disease during a 10 year period and at the start of the programme 96 per cent of the herd's 104 breeding animals were seropositive to the Aujeszky's virus. In addition, there was serological evidence of active virus circulation among younger animals. During the programme, all breeding animals were vaccinated every sixth month and replacement animals were tested free of disease and vaccinated before entry into the herd. When the originally seropositive animals had been rotated out of the herd, all breeding animals and a sample of weaner pigs were tested twice at six weeks' interval. No seroconversions to gI had taken place and the herd was declared Aujeszky's disease-free, 22 months after the start of the programme.

Experimental infections of goats with Mycoplasma mycoides subspecies mycoides, LC type

In five experiments 29 goats were infected experimentally by five different routes with a strain of Mycoplasma mycoides subspecies mycoides, LC type, isolated from a contagious caprine pleuropneumonia-like outbreak on a farm in northern Sweden. All the goats were colonised except those inoculated subcutaneously with small doses. In its pattern of pathogenicity this strain was similar to other experimentally tested strains except that peroral infection in kids produced no clinical signs. A 'contact' goat was also colonised but the clinical signs seen in it were probably due to a concomitant infection with Pasteurella haemolytica.

Epidemiological evaluation of the salmonella-controlling effect of a nationwide use of a competitive exclusion culture in poultry

The purpose of the study was to evaluate the salmonella contamination-controlling effect of a nationwide use of a competitive exclusion culture in poultry. During a 5-yr period, a bacterial flora from caecum of adult birds was given to broiler chickens in order to control salmonella infection. The culture was given on 144 occasions to a total of 2.86 million chickens. The base for the evaluation was the compulsory and regular control for salmonella contamination conducted according to the salmonella control program applied to Sweden. Epidemiological evaluation, especially in relation to the use of the culture during a period when salmonella was spread from a feed factory, strongly supports the conclusion that the culture has a salmonella contamination-preventing effect under field conditions, as earlier had been found in laboratory studies. Questionnaires answered by producers did not indicate significant adverse effects of the treatment.

Animal consumption of antibiotics and chemotherapeutic drugs in Sweden during 1980, 1982 and 1984

The total animal consumption of antibiotic and chemotherapeutic drugs in Sweden during 1980, 1982 and 1984 has been studied. The study also included coccidiostatic, antiparasitic and antimycotic drugs. The total animal consumption during the years mentioned was 66.1, 68.8 and 72.6 tons of active substance, respectively, and the amount of antibacterial drugs for therapy was 28.7 (43.4%), 29.1 (42.5%) and 34.1 (47.0%) tons, respectively. Tetracycline, penicillin, sulphonamide and aminoglycoside were the four major groups of antibiotics used for therapy of bacterial infections in animals. The consumption was related to the metabolic bodyweights of animals which were the potential consumers. A comparison was also made with the corresponding human consumption during 1980. The data on antibiotic consumption can be divided by county and compared to the animal population and disease situation in each county. This study thus offers a good base for further investigations on different aspects of the use of antibiotics.

Pathogenicity for chickens of a paramyxovirus type 1, isolated from racing pigeons in Sweden

Strains of paramyxovirus type 1 (PMV-1) have been isolated from diseased racing pigeons in Sweden. One of these isolates was selected for studies of the pathogenicity and contagiousness in chickens.

The same isolate was previously found to have a high intravenous pathogenicity index (IVPI) in 6 weeks old chickens.

In three experiments it was found that the PMV-1 isolate was very pathogenic for 1 week old chickens but not pathogenic for 120 day old pullets inoculated intranasally and ocularly.

Symptoms in the young chickens were similar to those seen in the neurotropic form of Newcastle disease. The mortality was high and the incubation period 5–11 days.

The disease easily spread to young chickens kept in contact with diseased birds.

The microscopic examination revealed an interstitial nonpurulent pneumonia and a nonpurulent encephalitis in the young chickens. In the pullets the only finding was a mild encephalitis.

PMV-1 was recovered from all young chickens but not from the pullets.

Both the chickens and the inoculated pullets developed antibodies to PMV-1.

Salmonella isolated from animals and feed stuffs in Sweden during 1978-1982

Regulations concerning the control of Salmonella in animals are more strict in Sweden than in most other countries, though a certain liberalization took place in 1982. The main purpose of these regulations is to prevent transmission of Salmonella infections from animals to man. Veterinarians and laboratories are obliged to report all Salmonella cases to the veterinary authorities. The cases are recorded by the Swedish Board of Agriculture. During the period of this report, 1978-1982, 1266 outbreaks of Salmonella in animals were recorded in Sweden. Isolated strains belonged to 78 different serotypes. The most frequent serotypes were S. typhi-murium (38.5% of the recorded cases) and S. dublin (37%). S. dublin was isolated mainly from cattle, while S. typhi-murium was isolated from a wide range of animal species. Next in frequency are some serotypes isolated mainly from chicken, at rates around 2%: S. livingstone, S. liverpool, and S. agona. Of the 78 isolated serotypes, 25 were never isolated before from animals in Sweden. There were 687 outbreaks of Salmonella recorded in cattle. Predominant serotypes are S. dublin (67% of the outbreaks in cattle) and S. typhi-murium (28%). The outbreaks of S. dublin, like earlier in the sixties and seventies, occurred mainly in south-eastern Sweden. The recorded occurrence of Salmonella in swine continued to decrease. During this period only 37 outbreaks were diagnosed. Of these more than half were caused by S. typhi-murium. S. choleraesuis was isolated from 6 cases only.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of feeding diets containing avoparcin and monensin on the occurrence of Salmonella in caecum and liver in experimentally infected chickens

In two experiments (Experiments A and B) chickens experimentally infected with S. infantis at 7 days of age and fed diets containing both avoparcin (10 ppm) and monensin (90 ppm) showed a higher frequency of Salmonella-positive livers and higher caecal counts of Salmonella 1 and 2 weeks after challenge than similarly infected chickens fed only avoparcin (10 ppm). The results may indicate a synergistic action between the two drugs on the ability of chickens to withstand Salmonella infections.

Evaluation of a killed feline panleukopenia virus vaccine against canine parvoviral enteritis in dogs

Immunogenic potency of a killed feline panleukopenia virus vaccine against canine parvoviral enteritis in dogs was examined. The vaccine elicited hemagglutination-inhibition antibodies to canine parvovirus (CPV) in all of the 72 dogs which were vaccinated. The vaccine was protective in dogs against both experimentally induced and naturally occurring CPV-induced disease. By statistical analysis, 4 weeks was found to be the optimal spacing between 2 vaccinal doses resulting in hemagglutination-inhibition antibody titers up to 1:5,120. Adverse reactions to the vaccine were not observed. Atypical lymphocytes were found consistently in the CPV-infected control dogs.

Antibiogram and production of beta-lactamase by canine isolates of Staphylococcus aureus

Clinical isolates of canine S. aureus strains (213) have been investigated for ability to produce beta-lactamase and sensitivity to 12 antibiotics. Fifty (23.5%) strains produced beta-lactamase. Using only the paper disc antibiotic diffusion method 17 of these would incorrectly have been classified was sensitive to beta-lactamase antibiotics. all strains were sensitive to methicillin, gentamicin and fusidic acid.

Bacteriologic examination of equine fecal flora as a diagnostic tool for equine intestinal clostridiosis

The fecal flora of 56 clinically healthy and 23 sick horses were examined bacteriologically for counts of Clostridium perfringens, molds, coliforms, alpha- and beta-hemolytic streptococci, and microbes belonging to genus Bacillus, as well as for the presence of Salmonella spp. Of the healthy horses, 85.7% had a C perfringens count less than 10(1) colony-forming units/g of feces. Of the healthy horses, lowest counts were found in race-horses. Of the sick horses, equine intestinal clostridiosis was diagnosed in 2 horses with large C perfringens counts (10(4) to 10(7) colony-forming units/g) and with acute diarrhea. The 7 isolates of C perfringens were identified as serotype A. Salmonella spp were not detected from any of the horses. The study indicated that diagnosing equine intestinal clostridiosis based on the determination of the fecal C perfringens count was suitable.

Concomitant occurrence of Campylobacter and parvoviruses in dogs with gastroenteritis

In 1979 a canine parvovirus infection was widespread among dogs in Sweden. During the epizootic faecal samples were taken for bacteriological examination from 77 hospitalised dogs at an animal clinic. Forty-nine of the dogs had signs of gastroenteritis and they were all infected with canine parvovirus according to serological investigations. The remaining 28 dogs were referred to the clinic for other reasons. Campylobacter was isolated from 23 out of the 49 dogs with gastroenteritis and from 4 out of 28 dogs lacking symptoms of enteritis. The significance of these findings is discussed.

Studies on in-use microbial contamination of sterile medicines at an animal hospital

Eye drops, injection solutions and infusion fluids in-use were collected from the various wards of an animal hospital and tested for sterility. Medicines from the stationary wards showed a contamination frequency of 17.5%, whereas 62% of those from the ambulatory ward were contaminated. The veterinarians who, as regards the handling of medicines, often have to work under extraordinary conditions must be observant of the risks of handling and keeping sterile medicines in an inconvenient way. This is especially important in ambulatory practice.

Epidemiological investigation of an animal house based upon phage-typing and biotyping of Staphylococcus epidermidis

The value of biotyping and phage-typing coagulase-negative staphylococci in the epidemiological investigation of a laboratory animal house was clearly demonstrated. In the animal rooms in which conventional bacteriological methods revealed equal bacterial contamination between a conventional unit and one housing specified-pathogen-free rodents, biotyping identified Staphylococcus cohnii as the only species in the latter, compared to S. warneri, S. hominis, S. saprophyticus. S. xylosus abd S. epidermidis as well as S. cohnii in the conventional unit. Similarly, phagetyping revealed 2 phage types in the specified-pathogen-free compared to 7 in the conventional unit. Thus biotyping and phage-typing provided evidence for the existence of a barrier between these units that had presented similar gross bacteriological findings.

Bacteriological examination of a modern animal house containing small laboratory animals

Floors and other areas totalling 1800 m2, comprising conventional and specified-pathogen-free (SPF) units, were screened bacteriologically 6 times in a year. The contamination indices observed were lower within than outside the units, and lower in the SPF than in the conventional unit. Bacterial counts in rooms containing animals in the conventional and SPF units were very similar. In all of the areas investigated within the units, most of the samples revealed less than 2 colony forming units per cm2. In contrast, high degrees of bacteriological contamination were detected in the changing rooms after showering or washing before entry. Staphylococcus epidermidis was the dominant bacterial species isolated. The bacteriological spectrum did not vary between the areas surveyed.

Antibiotic resistance and transferable antibiotica resistance Escherichia coli isolated from calves on a modern farm with therapeutic problems and unsatisfactory management conditions

On a farm with therapeutic problems and unsatisfactory management conditions, the occurrence of antibiotic resistance and transferable antibiotic resistance has been studied in E. coli isolated from calves which were 5 and 30 days old. Strains with resistance to up to seven antibiotics as well as transferable resistance against up to five antibiotics were recorded. On an average, 4.2 strains with different patterns and 4.0 different strains with transferable resistance were isolated from each calf. The corresponding figures previously found for healthy control calves were 1.6 and 1.1 strains, respectively. Resistance and transferable resistance were most common against sulphonamide and penicillin.

Production of coagulase, deoxyribonuclease and heat-stable deoxyribonuclease by canine isolates of staphylococci

Staphylococci isolated from different infections in dogs have been investigated for production of coagulase, deoxyribonuclease (DNase) and heat-stable DNase. Alll coagulase-positive strains (220) also produced DNase and heat-stable nuclease. However, 4 out of 15 coagulase-negative strains were also positive in both the DNase and the heat-stable DNase tests. Several tests for DNase and heat-stable DNase were evaluated. No strains were DNase-positive, heat-stable DNase-negative, or vice-versa.

[Anaerobic infections of domestic animals excluding enterotoxaemias (author's transl)]

With the advent of improved techniques for anaerobic cultivation on recent years increased interest in anaerobic infections has occurred. Against this background the present study presents a survey of those animal diseases (with the exception of the enterotoxaemias) in the pathogenesis of which anaerobic bacteria are involved.