Let’s meet up in Chicago!

chicago
Source: PadMapper.com

From Friday to Sunday, the North American PRRS Symposium will be happening in the InterContinental hotel in Chicago. This annual meeting, held on the first week-end of December in conjunction with the National Swine Improvement Federation, is for scientists, diagnosticians, practitioners and producers who are interested in porcine reproductive and respiratory syndrome virus (PRRSV), the most costly viral disease to ever face a global swine industry. The meeting is further expanded to include emerging and foreign animal diseases, such as Seneca Valley virus (SVV), porcine epidemic diarrhea virus (PEDV), porcine circovirus-associated disease (PCVAD), African swine fever virus (ASFV), classical swine fever virus (CSFV), and other high-consequence diseases of swine. Scientific topics include disease control, vaccines, pathogenesis, diagnostics, epidemiology and host genetics. This year meeting is dedicated to our friend and colleague Dr. Bob Morrison. The program of the conference is available online.

From the University of Minnesota, Dr. Montse Torremorell will be moderating a session regarding PRRS on the field whereas Dr. Cesar Corzo, Leman chair in swine health and productivity and Dr. Perle Boyer will be presenting respectively on the Morrison Swine Health Monitoring Program and PRRS genetic resistance: an online class for swine experts.

Concurrently to the North American PRRS Symposium, the Conference for Research Workers in Animal Diseases (CRWAD) will be held from Saturday December 2nd to Tuesday, December 5th at the Marriott in Downtown Chicago. There again, the University of Minnesota and more particularly the Veterinary Diagnostic Laboratory will be represented with the presentation of Dr. Talita Resende, a PhD candidate under the supervision of Dr. Connie Gebhart and Dr. Fabio Vannucci. Dr. Resende will be presenting on December 4th at 9:15 am on Evaluation of mouse enteroids as a in vitro model for Lawsonia intracellularis infection. Dr. Jorge Garrido from the Torremorell lab will be presenting on Novel approaches for influenza surveillance in swine breeding herds and Dr Robert Valeris-Chacin from the Myco Lab will be giving a talk on Survival analysis of protocols for eradication of Mycoplasma hyopneumoniae in swine farms.

Science Page: Monitoring breeding herd production data to detect PRRSV outbreaks

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.

This week, we are sharing a report from Drs. Gustavo Silva and Daniel Linhares and his team at Iowa State University.

Key points:

  • Systematic monitoring of key production performance indicators allowed for early detection of PRRS outbreaks.
  • Number of abortions was the most efficient parameter, detecting outbreaks up to 4 weeks before being reported to MSHMP.
  • Early detection of signals associated with disease outbreaks may help in preventing further spread of the virus to other herds, and allowing implementation of rapid response intervention(s).

Two-years worth of reproductive performance data from a production system with 14 breeding herds (1,512 herd weeks) was gathered. Weekly data on number of abortions, pre-weaning mortality (PWM) and difference between total born and born alive (neonatal losses), were merged with weekly MSHMP PRRSV status. A statistical process control method was used to scan production data for significant deviations from baseline.

Linhares EWMA application to detect significant deviation in abortions.gif
Example of EWMA application to detect significant deviation in abortions, compared to changes in PRRS status over time.

The time-to-detect outbreak, percentage of early detection of PRRSv-associated productivity deviations, and relative sensitivity and specificity of the production data monitoring system were determined relative to the MSHMP.

Abortion signals were detected 1 to 4 weeks before outbreaks were reported to the MSHMP. Most pre-weaning mortality signals coincided with the outbreak date reported to the MSHMP, and prenatal losses signals were detected from 1 to 3 weeks after the MSHMP reported outbreak date. Overall, the models had high relative sensitivity (range 85.7 to 100%) and specificity (range 98.5% to 99.6%) when comparing to the changes in
PRRS status reported in the MSHMP database.

Best of Leman 2017 series #2: P Yeske – A survival analysis of Mycoplasma hyopneumoniae elimination efforts

We launched a new series on the blog last month. Once a month, we are sharing with you a presentation given at the 2017 Allen D. Leman swine conference, on topics that the swine group found interesting, innovative or that lead to great discussions.

Our second presentation today is from Dr. Paul Yeske from Swine Vet Center, who is coming back on his experience with Mycoplasma hyopneumoniae elimination and giving us an update if the herds stayed negative.

To listen to this presentation, please click on the picture below:

Yeske Survival analysis of Mhyo elimination efforts Leman 2017

Happy Thanksgiving to you and your loved ones!

Flu control: it’s all about the piglet

Our latest collaboration with the National Hog Farmer was written by Drs. Montse Torremorell and Marie Culhane from the University of Minnesota.

Flu never seems to go away in some herds and that is because there are groups of pigs, or subpopulations, that are able to maintain and spread the flu virus.

One of the most important subpopulations that have been identified as sources of virus on a farm is the piglets. Piglets may be infected, but may not show any signs of disease, and as a result, are silent spreaders of flu. Then, at weaning, a small, but significant, percentage of the piglets can be subclinically infected with flu, meaning they appear healthy but are shedding flu at the nursery or wean-to-finish site.

This causes a challenge for producers because even though piglets are born free of flu, they tend to be contaminated by the dam during their second week of like. The peak of flu-positive piglets occurs at weaning when piglets are moved to a nursery where they may be put in contact with naive piglets from another source and therefore become a major source of infection.

We need to understand how piglets become infected in the farrowing room in order to prevent it. Sow vaccination is a tool commonly used to protect piglets via the transmission of antibodies through the colostrum or maternal immunity. It has been shown to decrease the prevalence of flu-positive piglets at weaning but is insufficient to constantly wean negative animals.

“At the University of Minnesota, we have been measuring the impact of piglets on the spread of flu for years. We found, in a study by Allerson of 52 swine breeding herds in the United States, 23 herds (44%) tested IAV RT-PCR positive at least once during a six-month study period. Groups of piglets from those herds also tested positive for flu at weaning about 25% (75 of 305) of the time.

Along those same lines, Chamba and partnering sow farms reported that out of the 34 farms studied for more than five years, all sow farms tested positive for flu at one time or another and the level of flu infection in the groups of weaned pigs ranged from 7% to 57%. More importantly, in this study, approximately 28% (427 of 1,523) of groups of pigs tested positive at weaning. […]

Ultimately, the successful control of on-going flu infections in growing pigs will depend on the sow farm’s ability to wean a negative pig […]”

Click to read the entire article on the National Hog Farmer website.

Science Page: Why PRRS elimination doesn’t work in some herds

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.

This week, we are sharing an article by Dr. Amber Stricker from Suidae Health and Production, published in PigHealthToday.com

“Over the years, there’s been considerable progress in the development of strategies aimed at eliminating porcine respiratory and reproductive syndrome virus (PRRSV). I define successful PRRSV elimination as the absence of clinical disease in the breeding herd and, more importantly, the absence of the vertical transmission of virus to weaned pigs. Unfortunately, successful PRRS elimination isn’t always achieved in some herds, and I have several experiences that may help answer why.”
Dr. Stricker then compiles six reasons that, in her experience, led to a failure in PRRS elimination:
  • No break in disease cycle or insufficient herd closure
  • Incomplete exposure
  • Compliance problems
  • Holding back pigs
  • New virus introduction
  • Insufficient diagnostics

Take a look at the full article to read more about each of those facors.

A new multidrug resistant Salmonella enterica serotype found in Midwestern swine

Text reproduced from the Center for Infectious Disease Research and Policy (CIDRAP)

A new study by Dr. Julio Alvarez‘s team from the STEMMA laboratory, published  in Clinical infectious Diseases suggests that a Salmonella strain circulating in pigs in the US Midwest is part of an emerging clade from Europe that is resistant to multiple antibiotics and may pose a public health risk.

The strain, Salmonella 4,[5],12:i:-, causes many foodborne disease outbreaks mostly tied to pigs and pork products and is expanding in the United States, according to the report by researchers from Minnesota and the United Kingdom.

The team used whole-genome sequencing to assess the relatedness of 659 S 4,[5],12:i:- isolates and 325 S Typhimurium isolates from various sources and locations in the United States and Europe. They also searched for resistance genes and other virulence factors and, for 50 livestock isolates and 22 human isolates, determined the antimicrobial resistance phenotypes.

The researchers found that the S 4,[5],12:i:- isolates fell into two main clades, regardless of their host or place of origin. Eighty-four percent of the US isolates recovered from 2014 through 2016, including nearly all those from pigs in the Midwest, were part of an emerging clade. This clade carried multiple genetic markers for antimicrobial resistance, including resistance to ampicillin, streptomycin, sulphonamides, and tetracyclines.

In addition, phenotypic (actual) resistance to enrofloxacin and ceftiofur was found in 11 of the 50 tested livestock isolates and 9 of the 22 human isolates. This was accompanied by plasmid-mediated resistance genes.

The authors conclude that S 4,[5],12:i:- strains circulating in Midwestern swine herds “are likely part of an emerging multidrug resistant clade first reported in Europe, and can carry plasmid-mediated resistance genes that may be transmitted horizontally to other bacteria and thus could represent a public-health concern.”

Click on the banner below to access the entire article.

salmonella enterica multidru resistant Alvarez 2017

Abstract

Background
Salmonella 4,[5],12:i:-, a worldwide emerging pathogen that causes many foodborne outbreaks mostly attributed to pig and pig products, is expanding in the U.S

Methods
Whole genome sequencing was applied to conduct multiple comparisons of 659 S. 4,[5],12:i:- and 325 S. Typhimurium from different sources and locations (i.e. U.S. and Europe) to assess their genetic heterogeneity, with a focus on strains recovered from swine in the U.S. Midwest. In addition, presence of resistance genes and other virulence factors was detected and the antimicrobial resistance phenotype of 50 and 22 isolates of livestock and human origin, respectively, was determined.

Results
The S. 4,5,12:i:- strains formed two main clades regardless of their source and geographical origin. Most (84%) of the U.S. isolates recovered in 2014–2016, including those (50/51) recovered from swine in the U.S. Midwest, were part of an emerging clade. In this clade, multiple genotypic resistance determinants were predominant, including resistance against ampicillin, streptomycin, sulphonamides and tetracyclines (ASSuT). Phenotypic resistance to enrofloxacin (11/50) and ceftiofur (9/50) was found in conjunction with the presence of plasmid-mediated resistance genes (qnrB19/qnrB2/qnrS1 and blaCMY-2/blaSHV-12, respectively). Also, higher similarity was found between S. 4,[5],12:i:- from the emerging clade and S. Typhimurium from Europe than with S. Typhimurium from the U.S.

Conclusions
Salmonella 4,[5],12:i:- currently circulating in swine in the U.S. Midwest are likely part of an emerging multidrug resistant clade first reported in Europe, and can carry plasmid-mediated resistance genes that may be transmitted horizontally to other bacteria and thus could represent a public-health concern.

Science Page: Natural and experimentally-induced Senecavirus A infections in boars

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.

This week, we are sharing a study from Dr. Matt Sturos from the University of Minnesota, Veterinary Diagnostic Laboratory regarding Senecavirus A in boars.

Key points

  • Naturally-infected boars have been documented to shed Senecavirus A (SVA) RNA in semen for up to three months after exhibiting vesicular disease.
  • Experimentally-infected boars shed SVA RNA in semen for up to three weeks post-inoculation.
  • The majority of experimentally-infected boars did not exhibit clinical signs or develop apparent lesions.
Senecavirus A in boars
Testis of boar naturally-infected with Senecavirus A. Bright red areas indicate positive signal for SVA by in-situ hybridization.

“This update shows that SVA RNA is shed in semen from both naturally-infected and experimentally-inoculated boars. The prolonged shedding of viral RNA in semen and the presence of SVA RNA in the testes and tonsils of the naturally-infected boars for up to three months are concerning findings and raises the possibility of persistent infection in boars. While the duration of shedding in semen for the experimentally-infected boars was considerably shorter than for the naturally-infected boars, the fact that all contemporary-strain boars had PCR-positive semen on at least one collection indicate that shedding in semen is a repeatable phenomenon and shedding occurred in some boars which did not exhibit clinical signs or develop vesicular lesions. It is currently unknown whether semen from infected boars can serve as a source of infection if used to inseminate susceptible females.”