Application of multiblock modelling to identify key drivers for antimicrobial use in pig production in four European countries.

Antimicrobial use in pig farming is influenced by a range of risk factors, including herd characteristics, biosecurity level, farm performance, occurrence of clinical signs and vaccination scheme, as well as farmers' attitudes and habits towards antimicrobial use. So far, the effect of these risk factors has been explored separately. Using an innovative method called multiblock partial least-squares regression, this study aimed to investigate, in a sample of 207 farrow-to-finish farms from Belgium, France, Germany and Sweden, the relative importance of the six above mentioned categories or 'blocks' of risk factors for antimicrobial use in pig production. Four country separate models were developed; they showed that all six blocks provided useful contribution to explaining antimicrobial use in at least one country. The occurrence of clinical signs, especially of respiratory and nervous diseases in fatteners, was one of the largest contributing blocks in all four countries, whereas the effect of the other blocks differed between countries. In terms of risk management, it suggests that a holistic and country-specific mitigation strategy is likely to be more effective. However, further research is needed to validate our findings in larger and more representative samples, as well as in other countries.

Landscape review about the decision to euthanize a compromised pig.

Timely euthanasia of a compromised pig in farming practice has been identified as a critical topic in veterinary medicine. The questions 'why and when are pigs euthanized' and 'what influences the decision making process' need to be answered to improve the situation. In the past five years, work addressing these issues has been published in the literature, however, a synthesis of the findings is missing. With the help of a quantitative and qualitative analysis, this paper has generated a landscape review to outline major topics, the role of clinical signs and further influences on the decision to euthanize a pig. Due to the quantitative content analysis, 58 topics have been identified with the role of welfare as a justification and training for caretakers in making euthanasia decisions as the most frequently mentioned. The qualitative analysis of why and when a pig is euthanized generated a set of clinical signs for organ tracts, and a set of categories influencing the decision making process. The results outline the need to increase research on details specific to understanding how clinical signs evolve over time before euthanasia. In summary, the analysis provides an overview of work in the field and ideas on how to close knowledge gaps in the future. Moreover, the article contributes to harmonize efforts in the field and underlines the need for more research about the care of compromised and injured pigs.

[Infectious agent detection in reproductive disorders in swine herds. Retrospective evaluation of diagnostic laboratory examinations]. / Erregernachweis bei Reproduktionsstörungen in Schweinebeständen. Retrospektive Auswertung labordiagnostischer Untersuchungen.

OBJECTIVE: The detection rate of various viral and bacterial agents causing reproductive failure in sows was analysed. MATERIAL AND METHODS: Samples from abortion/uterus (n=714), sera from weak born piglets (n=317), cervical swabs (n=881) and urogenital organs from slaughtered sows (n=416) that had been submitted between January 2006 and June 2009 were included in this analysis. Various PCR assays were run to detect PRRSV, PCV2, PPV, Chlamydia spp. and Leptospira spp. Other bacterial agents were examined using standard cultural methods. RESULTS: In material from abortion, detection rates of 14.7% for PCV2 and 6.8% for PRRSV EU genotype were revealed using PCR screening. The other agents were detected in single cases only (PPV 2.2%, PRRSV US genotype 1.8%, Chlamydia spp. 1.0%, Leptospira spp. 0.8%). Single PCR yielded a significantly higher detection rate for PCV2 than PCR screening. Comparing results from abortion/uterus and serum samples from weak born piglets, a significantly higher detection rate of PCV2 and PRRSV was found in sera. Bacteriological examination revealed bacterial agents in more than 75% of all cervical swabs. However, half of them had to be considered as contaminated due to the diversity of the isolated bacteria. Bacteriological testing of urogenital organs from slaughtered sows yielded positive results in 60% of all samples, with a remarkably lower proportion of contaminated samples of 7.4%. CONCLUSION: It is assumed that 60-70% of all cases of reproductive failure are similarly not caused by primary infections. If PRRSV infection is suspected, examination of serum samples from weak born piglets is much better than the testing of foetuses or other material from abortion. Due to poor detection rates, the examination of foetuses/abortion material by screening PCR cannot be recommended. In the case of bacterial infections of the urogenital system, the cultural examination of organs from slaughtered sows is more often successful than the testing of cervical swabs.

Lameness in fattening pigs - Mycoplasma hyosynoviae, osteochondropathy and reduced dietary phosphorus level as three influencing factors: a case report.

BACKGROUND: Multiple diagnostic procedures, their results and interpretation in a case with severe lameness in fattening pigs are described. It is shown that selected diagnostic steps lead to identification of various risk factors for disease development in the affected herd. One focus of this case report is the prioritization of diagnostic steps to verify the impact of the different conditions, which finally led to the clinical disorder. Assessing a sufficient dietary phosphorus (P) supply and its impact on disease development proved most difficult. The diagnostic approach based on estimated calculation of phosphorus intake is presented in detail. CASE PRESENTATION: On a farrow-to-finishing farm, lameness occurred in pigs with 30-70 kg body weight. Necropsy of three diseased pigs revealed claw lesions and alterations at the knee and elbow joints. Histologic findings were characteristic of osteochondrosis. All pigs were positively tested for Mycoplasma hyosynoviae in affected joints. P values in blood did not indicate a P deficiency, while bone ashing in one of three animals resulted in a level indicating an insufficient mineral supply. Analysis of diet composition revealed a low phosphorus content in two diets, which might have led to a marginal P supply in individuals with high average daily gains with respect to development of bone mass and connective tissue prior to presentation of affected animals. Finally, the impact of dietary factors for disease development could not be evidenced in all submitted animals in this case. CONCLUSIONS: Mycoplasma (M.) hyosynoviae was identified to be an important etiologic factor for disease. Other, non-infectious factors, such as osteochondrosis and claw lesions might have favored development of lameness. In addition, a relevant marginal P supply for pigs was found in a limited time period in a phase of intense growing, but the potential interaction with infection by M. hyosynoviae is unknown. The presented case of severe lameness in fattening pigs revealed that three different influences presumably act in pathogenesis. Focusing only on one factor and ignoring others might be misleading regarding subsequent decision-making for prevention and therapy. Finally, clinical symptoms disappeared after some changes in diet composition and anti-inflammatory treatment of individual animals.

Quantification of Lawsonia intracellularis in porcine faeces by real-time PCR.

AIM: To develop and to validate a method for the quantification of Lawsonia intracellularis in porcine faeces by real-time PCR. METHODS AND RESULTS: A real-time PCR including a calibrator based on plasmid DNA for quantification by means of DeltaDeltaCt method was evaluated. The parameters specificity, detection limit, quantification limit, linearity, range, repeatability, precision and recovery were validated. The detection limit of the agent was 1 copy per reaction, and quantification was reliable between 10(1) and 10(7) copies per microl reaction volume. The linearity calculated by logistic regression revealed a slope of -3.329 reflecting an efficiency of 99.7% for the assay. Moreover, it was shown that storage of samples and repetition of tests including DNA isolation by same or other investigators did not influence the outcome. CONCLUSION: The quantification method described herein revealed consistent results for the quantitation of L. intracellularis in porcine faeces samples. SIGNIFICANCE AND IMPACT OF THE STUDY: In contrast to common PCR in combination with gel electrophoresis, this validated quantification method based on real-time PCR enhances a reliable quantification and is even more sensitive.

[Swinepox--skin disease with sporadic occurrence]. / Schweinepocken--eine sporadisch vorkommende Hauterkrankung.

Swinepox virus infection results in an acute, mild or subclinical course and is characterised by typical poxvirus skin lesions in affected pigs. Additionally, sporadic vertical swinepox virus transmission leads to congenital generalised infection and subsequent abortion or stillbirth. The present report describes the occurrence of epidermal efflorescences in two piglets after intrauterine natural suipoxvirus infection. No clinical abnormalities of the gilt and littermates as well as in other pigs from this herd were present. One of the affected piglets was stillborn and submitted for necropsy, the other animal was alive at birth, but died 3 days later. Histologically, a proliferative to ulcerative dermatitis with epithelial ballooning degeneration and characteristic intracytoplasmatic inclusion bodies was observed. The pathomorphological and histopathological suspected diagnosis of a poxvirus infection was confirmed by electron microscopy. Furthermore, the agent was identified as suipoxvirus by polymerase chain reaction. As demonstrated here, obvious skin lesions in suipoxvirus infection leads to a suspected diagnosis in newborn piglets on macroscopic examination. However, further post mortem examinations, including electron microscopy as well as molecular techniques are essential for the identification of the aetiology and the exclusion of differential diagnoses. Because the disease only affected two pigs there was only a small economic loss. A valid diagnostic plays an important role in advising farmers and for herd health monitoring.

Association between antimicrobial usage, biosecurity measures as well as farm performance in German farrow-to-finish farms.

BACKGROUND: Antimicrobial usage in food producing animals is of major concern. A clear link between the extent of use and the development of antimicrobial resistance has already been demonstrated. To evaluate strategies that may reduce the antimicrobial usage while assuring pig health and welfare, it requires profound knowledge of factors that are associated with antimicrobial usage. Data on biosecurity and herd management practices are important parameters to identify risk factors which are related to a higher antimicrobial usage. To investigate between-farm variations of high and low usage the treatment incidence (TI) per age group in 60 German farrow-to-finish herds was qualitatively and quantitatively analysed and linked to biosecurity measures, and herd management characteristics. RESULTS: Weaned pigs received most of the treatments (median TI = 487.6), followed by suckling pigs (median TI = 138.9). Suckling pigs were treated with critically important antimicrobials (3rd and 4th generation cephalosporines) to a remarkable extent. The number of sows present at site (p < 0.01) and a low score for external biosecurity (p = 0.06) were associated with a higher antimicrobial usage in pigs from birth till slaughter. Herds with a higher treatment incidence in growing pigs (TI 200 days): i) were located in a region with a high pig density (p < 0.01), ii) had a less strict access check for visitors and personnel (p < 0.01) and iii) scored lower in the subcategory 'cleaning and disinfection' (internal biosecurity) (p < 0.01). Herds with a higher treatment incidence in breeding pigs weaned more piglets per sow and year and scored better in the internal biosecurity level (p = 0.02). CONCLUSIONS: With the main focus on the treatment incidence in pigs from birth till slaughter and in breeding pigs risk factors for a high usage in these age groups were identified. The level of biosecurity of a herd was associated with the amount of antimicrobials used. Therefore, the findings in this study indicate possible points of action in the reduction and prudent use of antimicrobials in Germany. The active improvement of biosecurity measures could be a promising alternative to reduce antimicrobial usage on herd level.

[Transmission of agents of the porcine respiratory disease complex (PRDC) between swine herds: a review. Part 2--Pathogen transmission via semen, air and living/nonliving vectors]. / Die Ubertragung von Erregern des porcine respiratory disease complex (PRDC) zwischen Schweineherden--eine Literaturübersicht. 2. Mitteilung--Ubertragung durch Sperma, Luft und belebte/unbelebte Vektoren.

The transmission of PRDC-pathogens (PRRSV, influenza virus A, PCV2, M. hyopneumoniae, A. pleuropneumoniae) between swine herds, which was summarized in the first part of the review, mainly occurs via pig movement. The risk of pathogen transmission by insemination with contaminated semen plays only a relevant role in the infection with PRRSV and PCV2. A risk of the aerogen transmission of pathogens between herds within a distance of 2 to 3 km is described for M. hyopneumoniae and PRRSV. Evidence for the other pathogens is not investigated. The PRDC-pathogens are frequently detected in wild boar populations. Therefore, the transmission between wild boars and domestic pigs seems possible by close contacts. PRRSV and M. hyopneumoniae can be transmitted by contaminated clothes and boots, but the use of sanitation protocols appears to limit their spread. Live vectors like rodents or birds seemed to have no special importance for the transmission of PRDC-pathogens.

[Transmission of agents of the porcine respiratory disease complex (PRDC) between swine herds: a review. Part 1--diagnosis, transmission by animal contact]. / Die Ubertragung von Erregern des porcine respiratory disease complex (PRDC) zwischen Schweineherden--eine Literaturübersicht. 1. Mitteilung--Diagnostik, Ubertragung durch Tierkontakte.

Knowledge on the different ways of transmitting PRDC pathogens (PRRSV, influenza virus A, PCV 2, M. hyopneumoniae, A. pleuropneumoniae) between swine herds is of special interest for the development of biosecurity measures or the retrospective risk analysis in the framework of activities of the consulting veterinarian. In this literature review the current knowledge of the transmission of PRDC-pathogens is summarized. Since the assessment of investigations into pathogen detection in detail is influenced considerably by the chosen test for the diagnosis, the standard methods of routine diagnostic procedures are described. In this context the limits of the interpretation of the diagnostic findings are especially described in detail. Finally, the transmission caused by pig movement is summarized in this first part of the review.

[Possibilities and limits of serological diagnosis in pig stocks in the case of Mycoplasma hyopneumoniae infection]. / Möglichkeiten und Grenzen serologischer Diagnostik im Rahmen der Bestandsbetreuung von Schweinen am Beispiel der Mycoplasma- hyopneumoniae-Infektion.

When conducting their investigations to diagnose infectious diseases in swine, practitioners are often forced to use reduced numbers of animals in their samples in order to minimize costs for farmers. A cross-sectional study was conducted approximating such field conditions to show the limits of interpretation with reduced sample sizes in case of Enzootic Pneumonia. Compared with other respiratory pathogens, Mycoplasma hyopneumoniae, the etiologic agent of Enzootic Pneumonia spreads very slowly, mainly when animals are in direct contact. Furthermore, the interpretation of serological results is difficult because several weeks must usually pass for serological reactions to become apparent. Serological testing is normally used to confirm a clinical diagnosis by detecting an increase in antibodies against the etiologic agent. Samples are collected at the beginning of disease and four to six weeks later. An increasing number of serological positive animals in a herd is usually interpreted as spread of infection. The ,,true" prevalence we observed in our investigation was used to make a statistical analysis describing the probability of detecting an increasing prevalence from 0.07 to 0.33 with a reduced sample size. We showed that the probability of detecting an increase of two seropositive animals was 44% if 5 samples per group were analysed. When only 3 samples were analysed per group, this probability decreases to 21%. Compromise must be found between epidemiological necessary and financially acceptable sample size; this could be a minimum of 10 samples per age group.

The biosecurity status and its associations with production and management characteristics in farrow-to-finish pig herds.

Disease prevention through biosecurity measures is believed to be an important factor for improvement of the overall health status in animal production. This study aimed at assessing the levels of implementation of biosecurity measures in pig production in four European Union (EU) countries and to describe possible associations between the biosecurity level and farm and production characteristics. A cross-sectional study was conducted in 232 farrow-to-finish pig herds in Belgium, France, Germany and Sweden between December 2012 and December 2013. The biosecurity status in each of these herds was described and quantified by using the risk-based scoring tool Biocheck.UGentTM (www.biocheck.ugent.be). Production and management characteristics, obtained from the herd management system and by interviewing the farmer, were analysed for their association with the biosecurity level. A causal path was designed to study statistical associations. The results showed that there was substantial room for improvement in the biosecurity status on many pig farms. Significant differences (P<0.01) both in internal and external biosecurity levels were observed between countries. The external biosecurity status, combining all measures taken to prevent disease introduction into the herd, was highest in Germany and lowest in France. The internal biosecurity status, combining all measures taken to prevent within herd disease transmission, was highest in Sweden and lowest, with a large variation, in Belgium. External biosecurity scores were in general higher compared to internal biosecurity scores. The number of pathogens vaccinated against was significantly associated with internal biosecurity status, suggesting an overall more preventive approach towards the risk of disease transmission. A higher external biosecurity was associated with more weaned piglets per sow per year. Furthermore also the weaning age and the mortality till weaning were highly associated with the number of weaned piglets per sow per year. The negative association observed between the biosecurity level and the estimated frequency of treatment against certain clinical signs of disease as a proxy for disease incidence is consistent with the hypothesis that a higher biosecurity level results in healthier animals. These findings promote an improved biosecurity status at pig farms and are of relevance in the discussion on alternative ways to keep animals healthy with a reduced necessity of antimicrobials; Prevention is better than cure!

Higher perceived risk of antimicrobials is related to lower antimicrobial usage among pig farmers in four European countries.

The prudent use of antimicrobials (AMs) should be widened in pig farming to reduce the risk of AM resistance (AMR) in human and veterinary medicine. It is therefore important to understand pig farmers' motivators and the barriers to AM usage (AMU) on their farms. The authors investigated pig farmers' self-estimated levels of AMU, their perceived benefits and risks and the need for AMs in a cross-sectional survey in Belgium, France, Germany and Sweden. The authors also compared these perceptions between the four countries and related them to pig farmers' actual AMU. The results showed that farmers who used more AMs also estimated their own usage as higher. Farmers perceived many benefits but relatively few risks of AMU in pig farming. Some significant cross-country differences in farmers' perceptions were found, but they were relatively small. After controlling for country differences and farm differences, only perceived risks had a significant association with AMU. The authors therefore conclude that in order to promote prudent AMU, it seems most promising to focus on the structural differences in pig farming and veterinary medicine (e.g. legislation, role of the veterinarian) among countries. In addition, interventions which aim at reducing AMU should increase farmers' awareness of the risks of extensive AMU.

A Comparison of Pig Farmers' and Veterinarians' Perceptions and Intentions to Reduce Antimicrobial Usage in Six European Countries.

Antimicrobial (AM) resistance is an increasing problem in human and veterinary medicine. To manage this problem, the usage of AM should be reduced in pig farming, as well as in other areas. It is important to investigate the factors that influence both pig farmers' and veterinarians' intentions to reduce AM usage, which is a prerequisite for developing intervention measures. We conducted a mail survey among pig farmers (N = 1,294) and an online survey among veterinarians (N = 334) in Belgium, Denmark, France, Germany, Sweden and Switzerland. The farmers' survey assessed the perceived risks and benefits of and need for AM usage; the intention to reduce AM usage; farmers' efficacy (i.e. perception of their ability to reduce AM usage); support from their veterinarian; and the future reduction potential of AM usage. Additionally, self-reported reduction behaviours, the perceived farmers' barriers to reduce AM usage and relationships with farmers were assessed in the veterinarians' survey. The results showed that farmers and veterinarians had similar perceptions of the risks and benefits of AM usage. Veterinarians appeared to be more optimistic than pig farmers about reducing AM usage in pig farming. Farmers believed that their efficacy over AM reduction was relatively high. Farmers' intention to reduce AM usage and veterinarians' self-reported reduction behaviours were mainly associated with factors concerning the feasibility of reducing AM usage. To promote prudent AM usage, pig farmers should learn and experience how to reduce usage by applying alternative measures, whereas veterinarians should strengthen their advisory role and competencies to support and educate farmers.

[Vaccination of sows against Mycoplasma hyopneumoniae with Hyoresp]. / Impfung von Sauen gegen Mycoplasma hyopneumoniae mit Hyoresp.

The aim of the study was to investigate the serological reactions of pregnant sows to vaccination with Hyoresp. Further investigations were performed in the offspring of these sows to follow the dynamics of maternal antibodies and the reaction to vaccination at different points in time. The study was conducted in three farrow-to-finish herds endemically infected with M. hyopneumoniae. A total of 30 gilts and 31 sows were vaccinated 8 and 4 weeks ante partum with Hyoresp (Merial GmbH) or given phys. saline solution as a placebo. The offspring was divided into three groups receiving Hyoresp at 1 and 4 or at 4 and 8 weeks of age. The control group was treated with phys. saline solution at 1 and 4 weeks of age. Before vaccination, antibodies against M. hyopneumoniae were detected in 85% of the gilts and 68% of the sows, confirming the endemic infection of the herds. Vaccination of the sows induced a significant increase in the antibody concentration in serum within four weeks and enhanced the concentration of antibodies in the colostrum. As expected, significantly enhanced levels of antibodies were also detected during the first four weeks of life of the offspring of vaccinated sows. The piglets' serological reaction to vaccination at 1 and 4 weeks of age showed marked interferences with maternal antibodies, so that a reaction could be demonstrated only at 8 weeks of age. The serological reaction of piglets vaccinated at 4 and 8 weeks of age was much stronger than that of piglets vaccinated earlier. Surprisingly, the vaccination status of the sow had no effect on the serological response of the piglets in either vaccination scheme. Maternal antibodies are known to reduce the risk of M. hyopneumoniae infections in piglets. Vaccinating the sows against M. hyopneumoniae may thus be an option for farrowing-to-finish herds with an enhanced risk for infections due to ineffective separation of different age groups, poor gilt acclimatisation or high gilt replacement rates.

Delayed-nonmatching-to-sample performance is impaired by extensive, but not by limited, lesions of the thalamus in the rat.

Two experiments were conducted to determine whether lesions affecting limited areas of the thalamus can impair the performance of rats on a spatial delayed-nonmatching-to-sample (DNMTS) task trained before surgery. In Experiment 1, DNMTS was not affected by lesions produced by injecting 5 microliters of 1 mM N-methyl-D-aspartate into either the midline thalamus (n = 16) or bilaterally 1.0 mm from the midline (n = 16). In experiment 2, radio-frequency lesions were made 1.0 mm lateral to the midline at 3 anterior-posterior locations that destroyed the full rostral-caudal extent of the lateral internal medullary lamina (L-IML; n = 8), or at single anterior-posterior locations that destroyed either the anterior (n = 8) or posterior (n = 8) portions of the L-IML site. Although complete L-IML lesions disrupted DNMTS performance to an extent comparable to that of another study (Mair & Lacourse, 1992), lesions that were restricted to either the anterior or posterior portion of the L-IML site had no significant effect on this task.

[Significance of PRRS virus infections for respiratory tract infections in swine--a literature review]. / Die Bedeutung des PRRS-Virus für Erkrankungen des Respirationstraktes beim Schwein--eine Literaturübersicht.

The paper summarises present knowledge concerning the possible role of a virus which has in the meantime been classified as belonging to the arteriviridae and which causes PRRS (Porcine Reproductive and Respiratory Syndrome), in the pathogenesis of respiratory diseases four years after first isolation of the virus. Although the fact that PRRSV-infection produces an immunity which protects swine from repeated bouts of PRRSV is common knowledge by now, reinfection with the virus might be possible. An immunosuppression, which has been suggested by many investigators, and which was thought to be the result of destruction of alveolar macrophages during virus replication, was not found as yet. The significance of the extent and the duration of the decrease in the number of alveolar macrophages, which belong to the unspecific immunity, for the total immune system of swine infected with PRRSV remains unclear. A general impairment of specific immunity through PRRSV-infection could not be shown. The present role of PRRS for the pathogenesis of respiratory disease is seen very differently. The significance of PRRSV as primary cause of an "influenza-like" illness which is principally followed by severe bacterial infection of the respiratory tract, is questioned by the results of studies which identify PRRSV-infection as a mainly subclinical disease. In these studies, clinical cases are the exemption. Attempts at experimental reproduction of a clinically manifest, respiratory disease was not successful as yet. The paper describes factors which might be responsible for these variable results. Control of PRRS is difficult in areas with a high density of the swine population, since the spreading of the virus with the wind seems to be important besides the recruitment of new, infected animals. A vaccine has not yet been registered in Germany. First experimental experiences with vaccination are available from Denmark and the USA.

[Epidemiologic studies of the course of reproductive events after epidemic late abortion (PRRS/PEARS) in swine breeding herds]. / Epidemiologische Untersuchungen zum Verlauf des Reproduktionsgeschehens nach dem Seuchenhaften Spätabort (PRRS/PEARS) in Schweinezuchtbeständen.

The evaluation of the reproductive performance in nine pig breeding herds that have been affected with PRRS in the beginning of 1991 is carried out by comparing data prior to, during and after the acute phase of PRRS. Piglet losses were increased during four month, performance data, such as percentage of return to oestrus and the interval between farrowings did not show substantial alterations from the pre-epidemic data. The evaluation of reproductive performance of gilts bought in the post-epidemic period did not reveal any depression. Sows which farrowed in the acute epidemic phase of the disease (even those with abortions) returned to their pre-epidemic level of reproductive performance in the following litter. A longlasting immunity due to the persistence of the PRRS virus in the region is discussed as cause for the return of the reproductive performance to the pre-epidemic level.

[The surgical treatment of intestinal prolapse (prolapsus recti) in fattening swine under practice conditions]. / Erfahrungen mit der chirurgischen Behandlung von Darmvorfällen (Prolapsus recti) beim Mastschwein unter Praxisbedingungen.

The amputation of the prolapsed rectum of 102 pigs of a fattening unit was carried out by means of a 5-10 cm piece of a plastic hose inside and a ligation around the prolapse. The pressure necrosis due to the ligation leads to the amputation of the prolapse. The positive effect of this method on the performance of the pigs was demonstrated by comparing the 102 treated pigs with a group of pigs that were not treated and with the non-diseased control group. Additionally the influence of diarrhoea and coughing on the frequency of rectal prolapses was investigated.

[The control of Aujeszky's disease using surface vaccination. 2. Serologic studies of the occurrence of latent infection by Aujeszky's disease virus in fattening swine]. / Die Bekämpfung der Aujeszkyschen Krankheit mit Hilfe der Flächenimpfung. 2. Mitteilung: Serologische Untersuchungen zum Vorkommen der latenten Infektion mit dem Virus der Aujeszkyschen Krankheit bei Mastschweinen.

The aim of the study was to prove in a region in the North-West of Germany that there is the possibility to decrease the prevalence of latent Aujeszky's Disease infections by means of a systematic vaccination. For this, the most important precondition of the success in a high population immunity that is maintained also in the finishing pig until slaughter. Since it is known that maternal antibodies interfere with the active immunization in the prefattening period, procedures were to be found that guarantee a high immunity in spite of the colostral antibodies. The results of the study show that the existing recommendation for vaccinating fattening pigs are sufficient for the prevalence of latent infections. They also confirm the necessity to carry out a check- and slaughter policy at the end of the eradication program.

Antibody reaction in immunologically naïve replacement gilts vaccinated with an attenuated PRRSV live vaccine.

OBJECTIVE: Serological testing of blood samples is commonly known as an approved method to diagnose infectious diseases. Likewise it is used for monitoring infectious diseases as it is fast and cost-effective. Nevertheless interpretation of results can be difficult, especially when the samples were taken from animals, which received a vaccination prior to the serological examination. This is mainly due to the fact, that not every vaccination induces a measurable antibody reaction. In this recent case gilts were vaccinated with an attenuated live vaccine and the serum samples were negative in the ELISA. The question aroused which serological reaction to a vaccine is expected under field conditions. MATERIAL AND METHODS: In order to clarify this question a group of 28 gilts negative for porcine reproductive and respiratory syndrome (PRRS) virus (from a verifiable PRRSV-negative stock) were vaccinated with an attenuated PRRSV vaccine and blood samples were taken on days 0, 2, 4, 8 and 15 post vaccinationem (p. vacc). To provide a reliable means of diagnosis the samples were tested with an antibody ELISA and RT-PCR. RESULTS: A replication of the vaccine virus was demonstrated via RT-PCR in 100% of the animals 4 days p. vacc. The first samples classified positive in the ELISA were detected 8 days p. vacc. On day 15 p. vacc. a positive serological result was obtained for all animals. CONCLUSION: The vaccination with an attenuated PRRSV vaccine provides a pronounced antibody reaction under field conditions. In case of a negative serological reaction in recently vaccinated pigs all steps from the manufacturing process through to the implementation of the vaccine have to be critically evaluated. Likewise correct laboratory studies and the assessment of diagnostic results need to be scrutinized.