Commercial production of swine often involves raising animals in large groups through the use of multi-stage production systems. In such systems, pigs can experience different degrees of contact with animals of the same or different ages. Population size and degree of contact can greatly influence transmission of endemic pathogens, including influenza A virus (IAV). IAV can display high genetic variability, which can further complicate population-level patterns. Yet, the IAV transmission in large multi-site swine production systems has not been well studied. The objectives of this study were to describe the IAV circulation in a multi-source nursery facility and identify factors associated with infection in nursery pigs. Pigs from five sow herds were mixed in one all-in/all-out nursery barn, with 81 and 75 pigs included in two longitudinal studies. Virus isolation was performed in Madin-Darby canine kidney cells and serology was performed using hemagglutination inhibition assays. Risk factor analysis for virological positivity was conducted using logistic regression and stratified Cox’s regression for recurrent events. In Study 1, at ≈30 days post-weaning, 100% of pigs were positive, with 43.2% of pigs being positive recurrently over the entire study period. In study 2, 48% of pigs were positive at the peak of the outbreak, and 10.7% were positive recurrently over the entire study period. The results suggest that IAV can circulate during the nursery phase in an endemic pattern and that the likelihood of recurrent infections was associated in a non-linear way with the level of heterologous (within-subtype) maternal immunity (p < 0.05). High within-pen intracluster correlation coefficients (> 0.75) were also observed for the majority of sampling times suggesting that pen-level factors played a role in infection dynamics in this study.Electronic supplementary materialThe online version of this article (doi:10.1186/s13567-017-0466-x) contains supplementary material, which is available to authorized users.

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Abstract. A polymerase chain reaction (PCR) assay was developed for the detection of Mycoplasma dispar in nasal mucus samples collected from calves. The target DNA sequence was the 16S rRNA gene, and the fragment was selected within a region of high polymorphism. The specificity and detection limit of the method were determined. This method was then used for the detection of M. dispar in nasal swabs collected from 301 calves, including 155 clinical samples from animals showing signs of respiratory disease and 146 samples from healthy animals. PCR with generic primers was applied to the detection of Mollicutes, followed by the detection of M. dispar. Mollicutes were detected in 52.05% of clinical samples from healthy animals and in 90.96% of samples from sick animals. Mycoplasma dispar was detected in 6.16% of healthy animals and in 34.84% of sick animals. The PCR assay was useful in verifying the presence of M. dispar in calves and may be a useful tool in monitoring this mycoplasma in cattle herds.

Five species of mycoplasma are associated with several rat diseases. Mycoplasma pulmonis is the most important and most studied, possibly causing disease in rats and undermining the validity of laboratory experiments. M. pulmonis was isolated in 144/240 laboratory rats and identified by PCR in 155/240. This species was also detected in 12 human individuals (technicians of a laboratory animal house hold) in contact with these rats. The results were confirmed by sequencing of DNA products. Mycoplasma species are host specific; however, M. pulmonis was identified in humans, suggesting a case of unspecific colonization. Statistical analysis shows a greater risk for M. pulmonis colonizing individuals who are exposed to infected rats in animal facilities than individuals who do not. The detection of M. pulmonis in humans indicates a new status for this mollicute mycoplasmas in animal-holding facilities.

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The detection and co-circulation of multiple variants of porcine reproductive and respiratory syndrome virus (PRRSV) have been observed and reported in swine. However, the potential long-term impact of multiple prevailing PRRSV variants on pig-performance is not yet fully understood. The primary objective of this study was to describe the genetic variation of PRRSV in processing fluid (PF), oral fluid (OF), and tonsil scraping (TS) specimens from five swine farms with different production types and PRRS status over a period of time (~1 year). Furthermore, the association between PRRSV prevalence and production parameters was investigated. Results showed that PRRSV was detected by RT-qPCR in 21–25% of all types of specimens. In breeding farms, PRRSV detection in PF and/or TS samples was correlated with stillborn and mummified fetuses, and pre-weaning mortality throughout the study period. Although ORF5 sequences were obtained in &lt;16% of all sample types, simultaneous detection of PRRSV variants including field and vaccine strains within a single sampling event was identified in both breeding and growing pig farms. Phylogenetic analyses based on the ORF5 sequence classified the detected field PRRSV into L1A and L1H, two sub-lineages of lineage 1 (L1). Our study demonstrated the presence of multiple PRRSV lineages, sub-lineages, and variants in swine herds and its potential association with swine reproductive performance under field conditions.

SummaryThe objective of this study was to investigate the association between environmental temperature and humidity and the presence of antibodies for two specific strains of swine influenza viruses: A/SW/ON/105-56/12/H3N2 (H3N2_D) and A/SW/ON/ 84/2012/H1N1 (H1N1_P). A cross-sectional study was performed in a commercial farm, and a total of 450 pigs at 10 weeks of age were blood sampled, by sampling 10 pigs per week for 45 weeks corresponding to 45 batches. Exposure of pigs to H3N2_D and H1N1_P virus was assessed by haemagglutination inhibition assay (HI), and a result of ≥1:40 was considered as indication of a positive exposure status for a specific strain. The selection of those two viruses was based on the fact that H1N1 was the dominant virus in Ontario herds, and H3N2 had been previously isolated in this particular farm. Environmental conditions were recorded through a portable device every 5 min and then summarized using descriptive statistics. The association between HI titres and environmental microconditions, in the nursery, was evaluated through random effect linear and logistic regression. The results showed that the prevalence for H1N1_P was high throughout the study (≥70%); however, for H3N2_D, the seroprevalence declined by the end of the study period.Results also showed an association between cumulative exposure to the viruses and temperature and relative humidity (p < .05). These results suggest that microclimate conditions can influence transmission patterns of influenza viruses in swine barns, and that even a herd with relatively simple demographics could have persistent and cocirculation of two different influenza A viruses IAV strains.antibodies, cocirculation, environment microclimate, humidity, swine influenza virus, Therefore, the objective of this study was to investigate the association between environmental temperature and humidity and the presence of antibodies for two specific strains of influenza viruses during the nursery phase of pig production. | MATERIALS AND METHODS | General overviewA 650-sow farrow-to-nursery farm located in southern Ontario was chosen for the study. The farrowing rooms and nursery rooms were operated in an all-in/all-out basis. Replacement gilts were purchased every 6 weeks from a single source and moved directly into the herd, with no prior off-site isolation. The farrowing area con- | Study populationA repeated cross-sectional study was performed between 18 April 2013 and 23 May 2014 in the nursery area. Each week during the study period, 10 pigs from the nursery room that held the oldest pigs, about 10 weeks of age, were selected for blood sampling. Sample size was sufficient to detect seroprevalence of 30% with 95%confidence, even with assay sensitivity that would be as low as 90%and 100% specificity. Such prevalence was considered as sufficient for the purposes of this study because of the timing of sampling (i.e., end of nursery) and the cumulative nature of the measured outcome (i.e., relatively long duration of antibodies). Two conveniently selected...

Porcine reproductive and respiratory syndrome virus (PRRSV) has been one of the major health-related concerns in the swine production industry. Through its rapid transmission and mutation, the simultaneous circulation of multiple PRRSV strains can be a challenge in PRRSV diagnostic, control and surveillance. The objective of this longitudinal study was to describe the temporal detection of PRRSV in swine farms with different production types and PRRS management strategies. Tonsil scraping (n = 344) samples were collected from three breeding and two growing herds for approximately one year. In addition, processing fluids (n = 216) were obtained from piglet processing batches within the three breeding farms while pen-based oral fluids (n = 125) were collected in the two growing pig farms. Viral RNA extraction and reverse-transcription quantitative PCR (RT-qPCR) were conducted for all samples. The sample positivity threshold was set at quantification cycle (Cq) of ≤ 37. Statistical analyses were performed using generalized linear modelling and post hoc pairwise comparisons with Bonferroni adjustments using R statistical software. The results suggested a higher probability of detection in processing fluids compared to tonsil scraping specimens [odds ratio (OR) = 3.86; p = .096] in breeding farms whereas oral fluids were outperformed by tonsil scrapings (OR = 0.26; p < .01) in growing pig farms. The results described herein may lead to an improvement in PRRSV diagnostic and surveillance by selecting proper specimens.