Science Page: PRRS eradication efforts in Chile: Current situation and future prospects

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 on PRRSV eradication efforts in Chile.

Key Points

  • After being introduced in 1999, PRRS was eradicated from the country in 2012.
  • In 2013 PRRS was again detected, sequence analysis suggested this was a new introduction to the country.
  • The Chilean swine industry and the Chilean Veterinary Services (SAG) expect to again eliminate the disease in the near future.

PRRS is a notifiable disease in Chile. It was first detected in 1999, and in 2000 both the swine industry and government joined efforts to eradicate the disease by a series of coordinated events including a mixture of herd closure and depopulation of infected premises. Vaccination was not allowed in the country to control PRRSV infection. The eradication program was completed in 2007 and as a result, Chile was declared PRRSV free in 2012. Nevertheless, on October 2013 clinical signs compatible with PRRSV were reported in a commercial sow farm. Since then, all commercial herds performed surveillance activities according to a risk score based on location and biosecurity measures. From October 2013 to October 2017, approximately 153,000 blood samples have been analyzed.

Chile eradication of PRRSVViral sequences obtained during the 2013 outbreak were compared to sequences from the early 2000s outbreak in Chile. Results showed a large genetic difference between isolates from both outbreaks. Further analyses demonstrated that the Chilean virus was closely related to a virus circulating in the state of Indiana in the US at the time of introduction. These results suggested that the latest PRRSV outbreak in Chile was most likely due to a new introduction into the country rather than a reemergence of a strain previously detected in Chile.

By October 2017, the disease was restricted to approximately 45,000 animals in six commercial farms owned by two companies that currently have eradication programs in place. These six infected commercial sites are clustered in three areas. (See figure above)

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!

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.

Influenza Herd-Level Prevalence and Seasonality in Breed-to-Wean Pig Farms in the Midwestern United States

The Torremorell lab is continuing to explore swine influenza epidemiology in this recent publication from Dr. Fabian Chamba Pardo in Frontiers in Veterinary Science. After showing that multiple genome constellations of similar and distinct influenza viruses co-circulate in pigs, the group is now presenting new data about influenza herd-level prevalence in the Midwest, and how it is influenced by seasons. Click on the banner below to read the entire research article.

Influenza seasonal prevalence Midwest herds Chamba 2017

60 sow farms from a single Midwestern production system were enrolled in this study. Between one and seven oral fluid samples were collected at each farm weekly and meteorological data (air temperature and relative humidity) was compiled from stations located from the farms.

Swine herd level prevalence Chamba 201728% of submissions had at least one influenza positive result. All farms tested positive at least once during study period. Herd-level prevalence ranged from 7% to 57% as show in the figure above. Prevalence was low in summer, rose during fall, and peaked twice in both early winter (December) and late spring (May). August was the month with the lowest prevalence. Influenza herd-level prevalence was higher when both mean outdoor air temperature and air humidity were lower.

The most common clades identified were H1 delta 1, H1 gamma 1, and clusters H3 IV A  and H3 IV B. Furthermore, 21% of the farms had 3 different influenza genetic clades circulating during the study period and 18% had 2.

Abstract

Influenza is a costly disease for pig producers and understanding its epidemiology is critical to control it. In this study, we aimed to estimate the herd-level prevalence and seasonality of influenza in breed-to-wean pig farms, evaluate the correlation between influenza herd-level prevalence and meteorological conditions, and characterize influenza genetic diversity over time. A cohort of 34 breed-to-wean farms with monthly influenza status obtained over a 5-year period in piglets prior to wean was selected. A farm was considered positive in a given month if at least one oral fluid tested influenza positive by reverse transcriptase polymerase chain reaction. Influenza seasonality was assessed combining autoregressive integrated moving average (ARIMA) models with trigonometric functions as covariates. Meteorological conditions were gathered from local land-based weather stations, monthly aggregated and correlated with influenza herd-level prevalence. Influenza herd-level prevalence had a median of 28% with a range from 7 to 57% and followed a cyclical pattern with levels increasing during fall, peaking in both early winter (December) and late spring (May), and decreasing in summer. Influenza herd-level prevalence was correlated with mean outdoor air absolute humidity (AH) and temperature. Influenza genetic diversity was substantial over time with influenza isolates belonging to 10 distinct clades from which H1 delta 1 and H1 gamma 1 were the most common. Twenty-one percent of farms had three different clades co-circulating over time, 18% of farms had two clades, and 41% of farms had one clade. In summary, our study showed that influenza had a cyclical pattern explained in part by air AH and temperature changes over time, and highlighted the importance of active surveillance to identify high-risk periods when strategic control measures for influenza could be implemented.

Science Page: Uterine prolapses trend in production sow 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 a study from Dr. Carmen Alonso and collaborators at Elanco.

Objectives of the study:

The objectives of the study, were: 1) to analyze the trends in prolapses of sows from 2012 to 2016, and 2) to evaluate the role of management practices, production parameters, and PRRS and PED disease status as covariates in the trend analysis of uterine sow prolapses.

Key points:

  • Uterine prolapse primarily affects sows around parturition and is still defined by an uncertain list of verified etiologies.
  • Since early 2013, swine companies have been experiencing an increase in the incidence of uterine prolapses in their herds.
  • Understanding the trends and potential risk factors would be crucial to improve the economics and welfare of the affected sow farms.

Uterine prolapses significant variables Alonso Results from this study indicate that the percentage of prolapsed sows has consistently increased every year (significant from 2014-2016) as a percentage of total deaths with the incidence being higher during the winter months and the lowest during the summer months. Total born, the use of toxin binder, assistance during farrowing, and PED health status had an association to sow deaths with prolapse per sows farrowed.

Click here to read the entire report on Uterine prolapses trends.

Dr. Connie Gebhart receives the BioMIC Excellence in Diagnostic Veterinary Microbiology Award

Dr. Connie Gebhart was honored during the last American Association of Veterinary Laboratory Diagnosticians (AAVLD) meeting  as the recipient of the BioMIC Excellence in Diagnostic Veterinary Microbiology Award.

Connie_Gebhart Supported by Biomic Inc, this prestigious AAVLD award recognizes distinguished scientist (s) for research accomplishments in the field that result in new scientific findings that have application for the betterment of veterinary medicine.
Dr. Connie Gebhart is full professor at the College of Veterinary Medicine at the University of Minnesota, USA. After obtaining both MS and PhD degrees in Veterinary Medicine from that college, she supervised multiple microbiology laboratories and projects until joining the faculty at the College of Veterinary Medicine in 2003. She currently holds a joint appointment with the Department of Veterinary and Biomedical Sciences and the Veterinary Diagnostic Laboratory as Faculty Advisor for Microbiology.
Dr. Gebhart has published over 100 peer reviewed manuscripts in internationally recognized journals and has co-authored seven chapters in books such as “Diseases of Swine”, “Bergey’s Manual of Systematic Bacteriology” and “Pathogenesis of Bacterial Infections in Animals”. She has been invited to speak at numerous national and international veterinary conferences such as the American College of Veterinary Internal Medicine, the American Association of Swine Veterinarians and the International Pig Veterinary Society, as well as for various universities and industries throughout the world.

As faculty, Dr. Gebhart is engaged in service, teaching and research concerning bacterial diseases, with special emphases on diagnosis and epidemiology of enteric diseases. Her research has focused on the obligately intracellular bacterium Lawsonia intracellularis and the novel porcine pathogen Brachyspira hampsonii. In particular, her laboratory was instrumental in identifying these new pathogenic species and continues to be active in studying all facets of these exceptional bacteria. Current research seeks to understand how L. intracellularis causes proliferation of enterocytes, by exploring processes such as interference with apoptosis, mechanism(s) of intracellular survival, alteration of normal cellular differentiation, and effect(s) on the enterocytes’ normal cell cycles.

Science Page: Describing the cull sow and cull hog market networks in the US: A pilot project

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 project from Dr. Jim Lowe at the University of Illinois.

Project rationale

“What is the range of locations of sows that enter a slaughter plant?, How many stops along the way do they make? and How long do they remain the slaughter channel?” These are the questions this project is planning to answer.

Key Points:

  • Little is known about the cull market, how culls are transported, and how they play a role in disease spread.
  • While most sows travel directly to slaughter, an important percentage most likely move through multiple collection points.
  • Cull sow movement are important for understanding disease transport related epidemiology.

Premise ID tags were collected during an entire week at a cull harvest plant. Animals originated from 297 unique source farms, located in 21 US states and Canada.

distance from farm to marketResults are shown in the histogram on the left.

The majority of culls (86%) originate less than 240km from the final collection point. This interaction is deemed to be a primary interaction, meaning that it is very likely the culls moved direct from the farm of origin to the final collection point. 14% of the culls travel a distance greater than 240km to the terminal collection point. Of these 14%, 17.7% or 2.5% of all culls, traveled 5 times as far to the last point of collection from the farm than they did from collection point to plant.

Click here to see the entire report on the cull sows and cull hogs market.