Subclinical colitis associated with moderately hemolytic Brachyspira strains

Our latest addition to the swine group at the University of Minnesota College of Veterinary Medicine is Dr. Matheus Costa whose research interests are in pathogen virulence mechanisms and more specifically swine dysentery and streptococcal meningitis.

In this latest publication in the Journal of Swine Health and Production, Dr. Costa and his former collaborators from the University of Saskatchewan introduced less-known Brachyspira strains and what their consequences are on the clinical level for the pig.

Summary

Objective: Microbiological and virulence characterization of 2 moderately hemolytic Brachyspira strains.

Materials and methods: Clinical isolates were obtained from diarrheic (3603-F2) and healthy (G79) pigs. Phenotypic characterization included assessment of hemolytic activity on blood agar and biochemical profiling. Genotyping was performed by sequencing the nicotinamide adenine dinucleotide oxidase (nox) gene, whole genome sequencing, and comparison to relevant Brachyspira. Pig inoculation included 4 treatment groups in 2 challenge experiments: negative control (sterile broth media; n = 12), positive control (Brachyspira hampsonii genomovar 2 strain 30446; n = 18), and 3603-F2 (n = 12) or G79 (n = 12). Fecal scoring and rectal swabbing for culture were performed daily. Animals were euthanized following onset of mucohemorrhagic diarrhea or between 21 and 28 days post inoculation (dpi). Gross and microscopic pathology were assessed. Terminal colon samples were used to characterize post-infection mucosal ion secretion.

 Hematoxylin and eosin (HE; bar = 200 µm) and Warthin-Faulkner (WF; bar = 20 µm) stained porcine colon from the challenge experiments. A) Negative control pig with normal colon, HE stain. B) Negative control pig with no spirochetes, WF stain. C) Positive control (30446) pig with moderate to severe muconecrotic colitis, HE stain. D) Positive control (30446) pig with many spirochetes in glands (arrows), WF stain. E) Strain 3046-F2 inoculated pig with moderately increased mucus, minimal necrosis and mild colitis, HE stain. F) Strain 3046-F2 inoculated pig with small numbers of spirochetes in glands (arrows), WF stain. G) Strain G79 inoculated pig with a mild mucus increase and minimal colitis, HE stain. H) Strain G79 inoculated pig with occasional glands containing many spirochetes (arrows), WF stain.

Results: Both strains were moderately hemolytic. Whole genome and nox sequencing identified 3603-F2 as Brachyspira murdochii and G79 as a novel strain. Both challenge trials revealed intestinal colonization, but no mucohemorrhagic diarrhea. Sporadic watery diarrhea was induced by 3603-F2 associated with a pattern of microscopic lesions similar to pigs with swine dysentery (positive controls). No diarrhea was observed in G79 inoculated pigs, but microscopic lesions were more severe than in controls. Both strains induced greater colonic anion secretory potential than negative controls 21 dpi.

Implications: Allegedly avirulent Brachyspira species most closely related to B murdochii can be associated with subclinical colitis and may be a concern for grow-finish pigs.

PRRS incidence rate by status at break

This is our Friday rubric: every week a new Science Page from the Bob Morrison’s Swine Health Monitoring Project. The previous editions of the science page are available on our website.

Key points

  • Current PRRS Chart 3 incidence risk by status does not take into account the time at risk farms contribute to each status.
  • Incidence rate takes into account the time a farm is at risk of disease.
  • Chart 3 will be replaced by a incidence rate chart that reflects more accurately the PRRS outbreak rate by status.
Continue reading “PRRS incidence rate by status at break”

What is the impact of zinc in late-gestation diets?

Image by Tim McReynolds from Pixabay

Our colleagues in the College of Food, Agricultural and Natural resource Sciences (CFANS) have shared one of their latest projects with the National Hog Farmer readers. They found that adding higher amounts of zinc in the late-gestation diet of sows in both a research and commercial herd increased the survival of smaller piglets until they are weaned.

Continue reading “What is the impact of zinc in late-gestation diets?”

Announcing MSHMP Report Changes

This is our Friday rubric: every week a new Science Page from the Bob Morrison’s Swine Health Monitoring Project. The previous editions of the science page are available on our website.

The MSHMP team would like to announce changes that will be coming to the weekly report in July, 2019 as we start a new monitoring year. Since mid 2017 we have been working towards switching the MSHMP database and report out of Excel and into a structured query language (SQL) database, with the report created using the programs R and LateX. We will officially make the transition starting July fifth and are excited to introduce you to some of the changes you will be seeing in the upgraded version of the MSHMP report.

The decision to transition into an SQL database and create the report with R and LateX was made primarily for 3 reasons: 1) Storage and query capabilities, 2) Reliability and 3) Automatization of the report generation process. Altogether this will improve the quality and speed of data management to continue to enable the project to grow in a constant manner.

The general contents and layout of the report will remain unaltered. The main change in the report is its overall appearance as the style, detail information and legends have been altered. The SVV chart show now only data from veterinary diagnostic laboratories. PRRSv Chart 3, incidence by Status, has been replaced by a new chart, PRRS Incidence Rate, to better reflect the status frequency of breaks.

The top paragraphs of the PRRSv and PEDv pages have been updated to more clearly reflect how systems are included in charts. We also show the amount of systems reporting each disease for the week out of the total number of systems, rather than out of the total included in a particular chart.

As a team we are very excited to launch our new more reliable and efficient database system and weekly report. We know it will enable our work to continue growing and improving, providing more value to the swine industry and associated communities. As a group we particularly want to acknowledge Post-Doc Juan Sanhueza and our IT Director Paulo Fioravante, the primary architects of the new system, and thank them for the immense amount of work they have done to make this possible.

Effect of litter aggregation and pooling on detection of PRRS virus in piglet processing fluids

The MSHMP team, led by Dr. Carles Vilalta published a new article in the Journal of Veterinary Diagnostic Investigation regarding the effect of pooling on the detection of PRRS in processing fluids.

The MSHMP team has been one of the first to publish data on the detection of PRRS in processing fluids. You may find all of our previous articles on processing fluids here.

Objectives of the study

  • Identify the limit of PRRS virus detection in pooled processing fluids
  • Evaluate the effect of pooling on the initial Ct value
Continue reading “Effect of litter aggregation and pooling on detection of PRRS virus in piglet processing fluids”