Antibodies against Dictyocaulus viviparus major sperm protein in bulk tank milk: Association with clinical appearance, herd management and milk production.

The objective of this study was to conduct a comprehensive field survey using a Dictyocaulus viviparus major sperm protein ELISA on bulk tank milk samples from Belgian dairy herds to gain insights in: (1) the sensitivity (Se) and specificity (Sp) of the test under field conditions; (2) the value of the test to predict a future clinical lungworm outbreak; (3) its associations with milk production parameters and (4) its associations with herd management factors. A total of 1248 herds were sampled, with samplings occurring in the middle ("August") and towards the end ("October") of the grazing season. A completed questionnaire on potential risk factors and potentially lungworm-induced clinical signs was obtained from 587 farms and milk production records could be obtained from 343 herds. The median (25th-75th percentile) D. viviparus antibody level (ODR) was 0.25 (0.19-0.31) in "August" and 0.24 (0.19-0.32) in "October". At a threshold of 0.41 ODR, the Se and Sp were estimated using mixture models at 50 and 99%, respectively. At the same threshold, the positive and negative predictive value of the ELISA applied in "August" on the occurrence of farmer-reported lungworm symptoms in the period August-November were 65% and 69%, respectively. D. viviparus antibody levels were significantly higher in the north vs. the south of the country, in large herds and in herds that did not mow pastures or that frequently purchased new animals. An increase in the ELISA result of "August" over the interquartile range was associated with a drop in the annual average milk yield, milk protein% and milk fat% of -0.50kgcow-1day-1, 0.02 and 0.02, respectively. The relationships between the ELISA results in "October" and milk production parameters were also negative, but lower and non- or only marginally significant. We conclude that the bulk tank milk ELISA has a low value to predict lungworm disease on an individual farm based on a fixed sampling date in the middle of the grazing season. On the other hand, the test has been potential to detect subclinical production impacts and study risk factors through epidemiological surveys.

Effect of sow vaccination against porcine circovirus type 2 (PCV2) on virological profiles in herds with or without PCV2 systemic disease.

We investigated porcine circovirus type 2 (PCV2) virological profiles in herds affected (PCVAD-AH, n = 5) or non-affected (PCVAD-NAH, n = 4) by PCV2-associated diseases (PCVAD), before and after 1 y of PCV2 gilt and sow vaccination. Fresh feces from the floor (5 pens/age/farm) and 5 blood samples (1/pen) were collected at 3, 9, 15, 21 wk. Individual feces and blood samples were collected from 5 gilts and 15 sows. Sampling was repeated 1 y after vaccination. Quantitative PCR on feces, PCV2 antibodies in blood serum and cell-mediated immunity were investigated. Before vaccination, pigs of PCVAD-AH had higher viral load in feces (9 and 15 wk), lower IgG and higher IgM (3 wk) and lower lymphocyte counts (9 and 15 wk) suggesting immunosuppression. Vaccination reduced viral load in growers, increased IgG (3 wk) suggesting improved maternal immunity, reduced IgM (3 wk), increased total antibody titers in sows and increased CD79a cells in the pigs.

Effet de la vaccination des truies contre le circovirus porcin de type 2 (PCV2) sur les profils virologiques des troupeaux atteints ou non de la maladie systémique PCV2. Nous avons fait une enquête sur les profils virologiques du circovirus porcin de type 2 (PCV2) dans les troupeaux affectés (PCVAD-AH, n = 5) ou non affectés (PCVAD-NAH, n = 4) par les maladies associées au PCV2 (MAPCV), 1 an avant et 1 an après la vaccination des cochettes et des truies contre le PCV2. Des fèces fraîches sur le plancher (5 enclos/âge/ferme) et 5 échantillons de sang (1/enclos) ont été prélevés à 3, 9, 15 et 21 semaines. Des fèces individuelles et des échantillons sanguins ont été préIevés auprès de 5 cochettes et de 15 truies. L'échantillonnage a été répété 1 an après la vaccination. La RCP quantitative sur les fèces, les anticorps de PCV2 dans le sérum sanguin et l'immunité à médiation cellulaire ont fait l'objet d'une enquête. Avant la vaccination, les porcs de PCVAD-AH présentaient une charge virale supérieure dans les fèces (à 9 et à 15 semaines), une IgG inférieure et une IgM supérieure (à 3 semaines) ainsi qu'une numération inférieure des lymphocytes (à 9 et à 15 semaines) suggérant l'immunosuppression. La vaccination a réduit la charge virale chez les porcs en croissance, a augmenté les IgG (à 3 semaines) suggérant une immunité maternelle améliorée, a réduit les IgM (à 3 semaines), a augmenté le total des titres d'anticorps chez les truies et a augmenté les cellules CD79a chez les porcs.(Traduit par Isabelle Vallières).

Case report: Helicobacter suis infection in a pig veterinarian.

This study describes a non-Helicobacter (H.) pylori Helicobacter (NHPH) infection in a pig veterinarian. The patient suffered from reflux esophagitis and general dyspeptic symptoms and was referred to the hospital for upper gastrointestinal endoscopy. Histologic examination of corpus and antrum biopsies revealed a chronic gastritis. Large spiral-shaped non-H. pylori helicobacters could be visualized and were identified as H. suis by PCR. The patient was treated with a triple therapy, consisting of amoxicillin, clarithromycin, and pantoprazole for 10 days. Successful eradication was confirmed after a follow-up gastrointestinal endoscopy and PCR 10 weeks after treatment. A mild chronic gastritis was, however, still observed at this point in time. This case report associates porcine H. suis strains with gastric disease in humans, thus emphasizing the zoonotic importance of H. suis bacteria from pigs.

An experimental Helicobacter suis infection causes gastritis and reduced daily weight gain in pigs.

Helicobacter suis is a zoonotically important bacterium, that has been associated with gastritis and ulcerative lesions of the pars oesophagea of the stomach in pigs. Its exact role in these pathologies, however, still remains controversial. Therefore, a total of 29 medicated early weaned piglets were inoculated intragastrically or orally, with a total of 2 × 10(9) viable H. suis bacteria and the effect on gastric pathology and weight gain was determined. Twenty-three medicated early weaned piglets were inoculated with a sterile culture medium and used as sham-inoculated controls. The animals were euthanized between 28 and 42 days after inoculation. Infected animals showed a more severe gastritis compared to the control group. There was also a significant reduction of approximately 60 g per day (10%) in weight gain in H. suis inoculated animals compared to the sham-inoculated control animals. In conclusion, this study demonstrates for the first time that a pure in vitro culture of H. suis not only causes gastritis but also a marked decrease of the daily weight gain in experimentally infected pigs.

A cross-sectional study of risk factors associated with pulmonary lesions in pigs at slaughter.

A cross-sectional study was conducted to identify herd-level factors that may influence the prevalence and severity of macroscopically visible pulmonary lesions in pigs at slaughter. Data were collected following abattoir inspection of 50 randomly-selected batches of 6335 pigs and by interviewing the producers. Macroscopic lung lesions were identified and scored semi-quantitatively in ≥ 80 pigs/herd and the prevalence of pleuritis and pneumonia was 20.76% and 23.85%, respectively. Following multivariable analysis, the seroprevalence of Actinobacillus pleuropneumoniae (P < 0.001) and Mycoplasma hyopneumoniae (P = 0.018) and the number of pigs/nursery pen (P = 0.023) were positively associated, whereas average weaning age was negatively associated (P = 0.001) with the pleuritis score. Risk factors associated with a higher prevalence of pneumonia were the presence of pleuritis (P = 0.001) and the frequent purchasing of pigs (P = 0.020). The findings of this study indicate that the prevalence of pleuritis and pneumonia remains high in Belgium and management factors are central to disease control.

Effect of administration of organic acids in drinking water on faecal shedding of E. coli, performance parameters and health in nursery pigs.

This study evaluated the effect of altering the pH of drinking water on the excretion of Escherichia coli (haemolytic and total count) by nursery piglets under field conditions as well as their performance parameters and health. The pH of the normal drinking water (pH 8) was lowered by using a mixture of organic acids (lactic, formic, propionic and acetic acid) to obtain a final pH of 6, 5 or 4. Reducing the pH to 4 resulted in the excretion of less faecal E. coli compared to pigs given water of pH 8 (P<0.05), but the fall in pH also significantly decreased water intake. The highest daily weight gain and lowest mortality rate were observed in the group receiving drinking water of pH 5 (P>0.05). No significant differences in the clinical parameters measured were seen between groups. The results of this study suggest that lowering the pH of the drinking water in newly weaned pigs reduces the E. coli load.

Gastric helicobacters in domestic animals and nonhuman primates and their significance for human health.

Helicobacters other than Helicobacter pylori have been associated with gastritis, gastric ulcers, and gastric mucosa-associated lymphoid tissue lymphoma in humans. These very fastidious microorganisms with a typical large spiral-shaped morphology were provisionally designated "H. heilmannii," but in fact they comprise at least five different Helicobacter species, all of which are known to colonize the gastric mucosa of animals. H. suis, which has been isolated from the stomachs of pigs, is the most prevalent gastric non-H. pylori Helicobacter species in humans. Other gastric non-H. pylori helicobacters colonizing the human stomach are H. felis, H. salomonis, H. bizzozeronii, and the still-uncultivable "Candidatus Helicobacter heilmannii." These microorganisms are often detected in the stomachs of dogs and cats. "Candidatus Helicobacter bovis" is highly prevalent in the abomasums of cattle but has only occasionally been detected in the stomachs of humans. There are clear indications that gastric non-H. pylori Helicobacter infections in humans originate from animals, and it is likely that transmission to humans occurs through direct contact. Little is known about the virulence factors of these microorganisms. The recent successes with in vitro isolation of non-H. pylori helicobacters from domestic animals open new perspectives for studying these microorganisms and their interactions with the host.

Protective immunization with homologous and heterologous antigens against Helicobacter suis challenge in a mouse model.

Helicobacter (H.) suis colonizes the stomach of more than 60% of slaughter pigs and is also of zoonotic importance. Recently, this bacterium was isolated in vitro, enabling the use of pure cultures for research purposes. In this study, mice were immunized intranasally or subcutaneously with whole bacterial cell lysate of H. suis or the closely related species H. bizzozeronii and H. cynogastricus, and subsequently challenged with H. suis. Control groups consisted of non-immunized and non-challenged mice (negative control group), as well as of sham-immunized mice that were inoculated with H. suis (positive control group). Urease tests on stomach tissue samples at 7 weeks after challenge infection were negative in all negative control mice, all intranasally immunized mice except one, and in all and 3 out of 5 animals of the H. cynogastricus and H. suis subcutaneously immunized groups, respectively. H. suis DNA was detected by PCR in the stomach of all positive control animals and all subcutaneously immunized/challenged animals. All negative control animals and some intranasally immunized/challenged mice were PCR-negative. In conclusion, immunization using antigens derived from the same or closely related bacterial species suppressed gastric colonization with H. suis, but complete protection was only achieved in a minority of animals following intranasal immunization.

Experimental quantification of the transmission of Porcine reproductive and respiratory syndrome virus.

We conducted an experiment to determine the ability of vaccine against Porcine reproductive and respiratory syndrome virus (PRRSV) to reduce the transmission of PRRSV among pigs. At the end of the experiment, transmission rates did not differ significantly (P = 0.61) between the vaccinated and nonvaccinated pigs, the mean R-values being 0.598 (95% confidence interval [CI] 0.136 to 3.218) and 0.264 (95% CI 0.008 to 2.266), respectively. The unusually low rate of PRRSV transmission in both groups may not have provided a sufficient challenge to detect a vaccine effect. Several factors could affect the rate of PRRSV transmission: isolate virulence, inoculation dose, inoculation route, number of passages of the challenge virus in cell culture, and population size. Of these, isolate virulence appears to be the most important factor associated with the low transmissibility observed in this study. More studies comparing rates of transmission between PRRSV isolates with diverse levels of virulence are needed to better understand this association.

Comparison of transmission of Mycoplasma hyopneumoniae in vaccinated and non-vaccinated populations.

A transmission experiment was performed to quantify the effect of vaccination on the transmission of Mycoplasma hyopneumoniae (M. hyopneumoniae) in nursery piglets by means of an adjusted reproduction ratio (R(n)). Thirty piglets, vaccinated at 1 week of age, and 30 non-vaccinated piglets, free of M. hyopneumoniae, were housed in six separate pens. In each pen, three animals that were intratracheally inoculated with M. hyopneumoniae, were housed together with seven contact piglets during the conventional nursery period of 6 weeks. At the end of the study, the infectious status of the animals was determined based on results of nPCR performed on bronchoalveolar lavage fluid. The R(n)-value in the vaccinated group was 2.38 (1.07-7.53) while in the non-vaccinated group, an R(n)-value of 3.51 (1.51-9.34) was observed, both not significantly different from each other (p=0.77). Under the actual experimental conditions, transmission of M. hyopneumoniae in nursery piglets was only numerically lower in vaccinated groups. In addition, vaccination with a conventional vaccine could not prevent the establishment of M. hyopneumoniae organisms in the lung.

Quantification of the spread of Mycoplasma hyopneumoniae in nursery pigs using transmission experiments.

Mycoplasma hyopneumoniae (M. hyopneumoniae) is present in almost all swine herds worldwide, but transmission of the pathogen through herds is not yet fully clarified. The aim of this study, performed in 2003, was to investigate and to quantify the transmission of M. hyopneumoniae under experimental conditions by means of an adjusted reproduction ratio (Rn). This Rn-value, calculated according to the final size method, expresses the mean number of secondary infections due to one typical infectious piglet during the nursery period. The period lasted from 4 to 10 weeks of age, corresponding with the nursery period used in most European production systems. Additionally, a comparison was made between transmissions of highly virulent and low virulent isolates. Forty-eight weaned piglets, free of M. hyopneumoniae, were housed in six separate pens. During 6 weeks, two animals experimentally infected with M. hyopneumoniae were housed together with six susceptible piglets. At the end of the study, the number of contact-infected animals was determined by the use of nPCR on bronchoalveolar lavage fluid. The Rn-values of the highly virulent and the low virulent isolates were estimated to be 1.47 (0.68-5.38) and 0.85 (0.33-3.39), respectively. No significant difference between the groups was found (P=0.53). The overall Rn was estimated to be 1.16 (0.94-4.08). Under the present experimental conditions, the transmission of M. hyopneumoniae, assessed for the first time by a reproduction ratio, shows that one piglet infected before weaning will infect on average one penmate during the nursery phase.