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.

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.

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.

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.

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!

Field study on swine influenza virus (SIV) infection in weaner pigs and sows.

OBJECTIVE: The aim of this field study was to explore the occurrence of and factors associated with the detection of swine influenza virus (SIV) by RTqPCR in weaner pigs and sows from herds with a history of respiratory or reproductive disorders. MATERIAL AND METHODS: The sample set was based on nasal swabs from 823 sows (123 submissions) and 562 weaner pigs (80 submissions). Nasal swab samples were taken and submitted by 51 veterinary practices from all over Germany. Corresponding to the pig density most of the submissions originated from the north-western part of Germany. The nasal swabs were used to detect SIV RNA by real-time RT-PCR (RTqPCR). Subtyping of SIV RNA by conventional RT-PCR and sequencing was attempted directly from clinical samples or from isolates when available. The herd characteristics, management and housing conditions of the pig herd as well as the course of the disease were collected by a telephone questionnaire with the herd attending veterinarian. RESULTS: SIV was detected by RTqPCR in 53.8% of the submissions from weaner pigs with a history of respiratory disease. Moreover SIV was detected in 10.6% of the submissions from sows. The predominant endemic subtype found in nasal swabs from sows and weaner pigs was H1N1 (60.5%) whereas subtypes H1N2 (14.0%) and H3N2 (14.0%) were detected less frequently. In addition, human pandemic H1N1 virus or reassortants thereof were found in 11.5%. CONCLUSION AND CLINICAL RELEVANCE: The results underline the significance of a SIV infection in young pigs. A significant lower detection of SIV in wea- ner pigs was associated with the vaccination of piglets against por- cine circovirus type 2 (PCV2), possibly indicating an interaction of SIV and PCV2. Most of the positive samples from sows originated from gilts, whereas only two originated from sows. An association between reproductive disorders and the detection of SIV could not be confirmed.

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.

Risk assessment of the introduction of porcine reproductive and respiratory syndrome virus via boar semen into Switzerland as an example of a PRRSV-free country.

Switzerland is currently porcine reproductive and respiratory syndrome virus (PRRSV) free, but semen imports from PRRSV-infected European countries are increasing. As the virus can be transmitted via semen, for example, when a free boar stud becomes infected, and the risk of its import in terms of PRRSV introduction is unknown, the annual probability to accidentally import the virus into Switzerland was estimated in a risk assessment. A quantitative stochastic model was set up with data comprised by import figures of 2010, interviews with boar stud owners and expert opinion. It resulted in an annual median number of 0.18 imported ejaculates (= imported semen doses from one collection from one donor) from PRRSV-infected boars. Hence, one infected ejaculate would be imported every 6 years and infect a mean of 10 sows. These results suggest that under current circumstances, there is a substantial risk of PRRSV introduction into Switzerland via imported boar semen and that measures to enhance safety of imports should be taken. The time from infection of a previously negative boar stud to its detection had the highest impact on the number of imported 'positive' ejaculates. Therefore, emphasis should be placed on PRRSV monitoring protocols in boar studs. Results indicated that a substantial increase in safety could only be achieved with much tighter sampling protocols than currently performed. Generally, the model could easily be customized for other applications like other countries or regions or even sow farms that want to estimate their risk when purchasing semen from a particular boar stud.

Herd-level risk factors for the seropositivity to Mycoplasma hyopneumoniae and the occurrence of enzootic pneumonia among fattening pigs in areas of endemic infection and high pig density.

The aim of the present study was to identify potential risk factors for the occurrence of enzootic pneumonia (EP) in herds situated in a region of high pig density, where a majority of herds is endemically infected with Mycoplasma hyopneumoniae. Between 2006 and 2010, overall 100 herds were enrolled in a case-control study. Data were collected through personal interview with the farmers, clinical examination of pigs and their environments, and serological testing for M. hyopneumoniae, swine influenza virus and porcine reproductive and respiratory syndrome virus. There were 40 case herds (coughing index high, seroprevalence high) with a mean coughing index of 4.3 and a seroprevalence of 86.6%. There were two control groups. Control group I consisted of 25 herds (coughing index low, seroprevalence low) with mean values of 0.7 and 11.2%, and 35 herds were allocated to control group II (coughing index low, seroprevalence high) where the mean coughing index was 0.9 and seroprevalence 86.3%. Case herds and control II herds had an increased age of piglets at weaning compared to control I herds. Any contact between fattening pigs of different age during restocking of compartments increased the risk for the occurrence of EP in a herd. Finally, farms that use living animals for the exposure to gilts during the acclimatization and farms that had increased number of weaned piglets per sow and year were less likely to test positive for M. hyopneumoniae and less likely to develop clinical symptoms of EP in fattening pigs.

Lameness in weaned pigs associated with tetracycline overdose. A case report.

On a piglet producing farm severe lameness was observed in pigs which had been weaned 3 weeks and longer due to severe distortions of joints and claws of fore and/or hind legs. Splaying of claws as well as flexural limb deformations particularly in the carpal joints increased in degree the older and heavier the pigs were. Because of coughing in the weaners, which had started 7-8 weeks before any lameness or limb deformation had been apparent, tetracycline was applied via water as medication. During the course of an on-site investigation, a miscalculation of dosage - 129-168 mg tetracycline per kg body weight - was revealed. It was therefore suggested to the farmer and his veterinarian to immediately stop the application of tetracycline and to use a different antibiotic against the still present coughing and sneezing. During a follow-up evaluation 4 weeks later, the farmer reported a significant decrease in affected animals. While a direct correlation between the lameness in the weaned pigs and the tetracycline dosage could not be proven, the existing evidence supports the theory that the overdosage was at least a contributing factor.

[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.

Occurrence of Mycoplasma hyopneumoniae infections in suckling and nursery pigs in a region of high pig density.

The occurrence of Mycoplasma hyopneumoniae infections in young pigs was surveyed in a retrospective study of 1122 datasets obtained from routine diagnostics where either suckling or nursery pigs were examined for M hyopneumoniae in lung tissue. Findings were correlated with the presence of lung lesions, detection of other respiratory pathogens, vaccination history and parameters describing the herd of origin. The prevalence of M hyopneumoniae in lung tissue from 201 suckling pigs was 2.0 per cent and, therefore, significantly lower than in lung tissue from 921 nursery pigs, which was 9.3 per cent. Previous use of antimicrobials and the vital status of the pigs when delivered for postmortem examination did not influence the detection of M hyopneumoniae infection. The presence of the porcine reproductive and respiratory syndrome virus (PRRSV)-EU genotype, Pasteurella multocida, Haemophilus parasuis, Mycoplasma hyorhinis or Streptococcus suis was correlated with a higher probability of also finding M hyopneumoniae. The history of vaccination, the time of the first or second application, and the type of vaccine (one- versus two-shot) did not influence the detection of M hyopneumoniae. A correlation between the type of herd and the presence of M hyopneumoniae was statistically insignificant and no effect of farrowing rhythm could be confirmed.

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.

Effect of a gonadotropin-releasing factor vaccine on follicle-stimulating hormone and luteinizing hormone concentrations and on the development of testicles and the expression of boar taint in male pigs.

The objective of this study was to determine the effect of using a gonadotropin-releasing factor (GnRF) vaccine on follicle-stimulating hormone (FSH) and luteinizing hormone (LH) concentrations in plasma, the size of testicles, and the expression of boar taint in male pigs. Vaccinated pigs were compared with surgically castrated pigs and entire males. Pigs were randomly assigned to three treatment groups: surgically castrated during the first week of life (T01, n=274), immunized twice during the fattening period with a GnRF vaccine, the first when 13 to 14 wk of age and the second when 20 to 21 wk of age (T02, n=280), and entire males (T03, n=56). From a subgroup of both T01 and T02 and from all pigs of group T03, blood samples were collected immediately before second vaccination (T02) and again before slaughter at either 24 to 25 or 26 to 27 wk of life to determine the plasma concentrations of LH and FSH. Testicles were removed after slaughter and their size was determined. Meat and fat samples from all pigs of T02 and T03 as well as 25% of the pigs of T01 were examined with the cold cooking and fat melting test. Immediately before the second vaccination (T02 only), LH and FSH concentrations were not significantly different between T02 and T03. However, LH and FSH concentrations were significantly higher in T01 compared with T02 and T03. Before the first slaughter date, LH and FSH concentrations were significantly lower in T02 than in T03. Testicle size was significantly lower in T02 compared with that in T03. In T02, 98% (235 of 239) of the samples were rated negative for boar taint by the cooking test, whereas in T03, 94% (48 of 51) were rated positive. In the fat melting test, 97% of T02 were rated negative and 3% (7 pigs) were rated positive, including the pigs tested positive in the cold cooking test. In T03, 94% were rated positive. All pigs (7 of 239) in T02 that were positive for boar taint in the cooking or melting test and that were tested had androstenone and skatole concentrations in backfat below threshold levels of 1 microg/g and 0.2 microg/g, respectively.

Occurrence of Mycoplasma hyopneumoniae in coughing piglets (3-6 weeks of age) from 50 herds with a history of endemic respiratory disease.

The objective of this study was to determine the occurrence of Mycoplasma hyopneumoniae in the lower respiratory tract of suckling and recently weaned pigs from herds with a history of endemic respiratory disease in this age group. Bronchoalveolar lavage fluid was obtained from 500 clinically affected piglets originating from 50 herds (10 piglets per herd). The presence of M. hyopneumoniae was examined by application of a nested polymerase chain reaction. Mycoplasama hyopneumoniae was detected in lavage fluid in 12.3% of the suckling piglets and 10.6% of the weaned piglets (mean 11.2%). The percentage of herds in which M. hyopneumoniae could not be detected was 72% and in two of the herds all samples were tested positive. Herd level information on relevant hygiene, housing and management factors was obtained by means of a structured questionnaire. The univariable data analysis (odds ratio) showed that the detection of M. hyopneumoniae in young piglets is associated with one- and two-site production and inappropriate gilt acclimatization.

[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.

Effect of natural exposure to vaccine-derived North American genotype PRRS virus on the serological response in naïve pigs.

Diagnosis of porcine reproductive and respiratory syndrome virus (PRRSV) is often performed by serological testing, but ELISA does not differentiate between infections with wild-type or vaccine virus. Two attenuated live vaccines [European (EU) or North American (NA) genotype] are used. In addition to wild-type isolates, vaccine or vaccine-derived viruses occur frequently. This is often not considered when the ELISA results are used to differentiate between epizootic and enzootic infections. In this study, an infection with the NA genotype vaccine-derived virus was detected in two herds previously PRRSV negative and ELISA results [sample to positive (s/p) ratios] were analysed. The virus was identified by RT-PCR and nucleotide sequences of ORF5 had 97% (herd A) and 99% (herd B) identity with the genome of a ML PRRSV vaccine belonging to the NA genotype. Pigs of different age became positive with an average s/p ratio of 2.24 (A) and 1.18 (B). The data clearly demonstrate that spontaneous infection with a vaccine-derived virus of the NA genotype induces ELISA s/p ratios similar to those induced by vaccination or by infection with wild-type virus. We conclude that for a correct interpretation of serological results the circulation of vaccine or vaccine-derived virus isolates has to be excluded by RT-PCR, even if vaccination is not ongoing.

[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.