Science page: Measuring production losses from endemic PRRS in US farms

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

Key points from this week edition

We analyzed performance records from 16 sow farms that were vaccinated with PRRS virus and experienced a PRRS virus infection.

Production dropped until the 6th week post-outbreak with a second decline between the 11th and 18th week post-outbreak.

We calculated an average decrease of 1.92 weaned pigs per sow (min=0.51, max=3.72) per year attributable to changes in farrow rate and prewean mortality.

The full report on production losses from endemic PRRS farms in the US is available.

 

 

Sample and diagnostic types for early detection of Mycoplasma hyopneumoniae

Summary:

Mycoplasma hyopneumoniae is the causative agent enzootic pneumonia, an economically significant disease in pigs. In this study published by Drs. Pieters and Rovira from the University of Minnesota, pigs experimentally inoculated with M.hyopneumoniae were sampled 0, 2, 5, 9, 14, 21, and 28 post-inoculation.

Different sample types were compared:

  • Nasal swabs
  • Laryngeal swabs
  • Tracheobronchal lavages
  • Oral fluids
  • Serum samples

Using different diagnostic tests:

  • PCR
  • ELISA IgG anti M.hyopneumoniae
  • ELISA Ig M anti M.hyopneumoniae
  • ELISA C-reactive protein

Laryngeal swab samples tested by PCR were highly sensitive for detection of Mycoplasma hyopneumoniae in live pigs.
Various commercial ELISA kits for detection of Mycoplasma hyopneumoniae antibodies showed similar sensitivity.
Oral fluids showed a low sensitivity for detection of Mycoplasma hyopneumoniae in experimentally infected pigs.

Pieters Mhyopneumoniae early detection test sample 2017

Abstract

Detection of Mycoplasma hyopneumoniae in live pigs during the early stages of infection is critical for timely implementation of control measures, but is technically challenging. This study compared the sensitivity of various sample types and diagnostic methods for detection of M. hyopneumoniae during the first 28 days after experimental exposure. Twenty-one 8-week old pigs were intra-tracheally inoculated on day 0 with M. hyopneumoniae strain 232. Two age matched pigs were mock inoculated and maintained as negative controls. On post-inoculation days 0, 2, 5, 9, 14, 21 and 28, nasal swabs, laryngeal swabs, tracheobronchial lavage fluid, and blood samples were obtained from each pig and oral fluid samples were obtained from each room in which pigs were housed. Serum samples were assayed by ELISA for IgM and IgG M. hyopneumoniae antibodies and C-reactive protein. All other samples were tested for M. hyopneumoniae DNA by species-specific real-time PCR. Serum antibodies (IgG) to M. hyopneumoniae were detected in challenge-inoculated pigs on days 21 and 28. M. hyopneumoniae DNA was detected in samples from experimentally inoculated pigs beginning at 5 days post-inoculation. Laryngeal swabs at all samplings beginning on day 5 showed the highest sensitivity for M. hyopneumoniae DNA Detection, while oral fluids showed the lowest sensitivity. Although laryngeal swabs are not considered the typical M. hyopneumoniae diagnostic sample, under the conditions of this study laryngeal swabs tested by PCR proved to be a practical and reliable diagnostic sample for M. hyopneumoniae detection in vivo during early-stage infection.

Link to the full-article

Science page: Mycoplasma hyorhinis and conjunctivitis in pigs

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

Key points from this week’s edition:

Conjunctivitis in pigs has been associated with various infectious agents, among them, Mycoplasma hyorhinis.
We investigated various outbreaks of conjunctivitis in pigs without apparent non-infectious predisposing factors.
Eye swabs and tissues from animals with conjunctivitis and non-affected contact pen mates were positive for M.hyorhinis by PCR and culture.
The exact role of Mycoplasmas in the development of conjunctivitis in pigs is still unclear.
The full report with pictures of the lesions is now available.

Air samples successful in detecting on-farm PRRSV, PEDV, and high-path avian influenza virus

Webinar on Senecavirus A from Dr. Sturos tomorrow 03/28 at 4pm

Matt Sturos
Dr. Matt Sturos

Dr. Matt Sturos, diagnostic pathologist at the University of Minnesota, Veterinary Diagnostic Laboratory will be presenting the latest information on Senecavirus A in swine, tomorrow at 4pm in a learning session organized by the Minnesota Veterinary Medical Association (MVMA). Participants can join in person at the MVMA conference room or online via WebEX.

 

More information here

NEW: Read the Swine Health Monitoring Project – Science Page here, every Friday

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The Swine Health Monitoring Project (SHMP) is a National program coordinated by Dr. Bob Morrison from the University of Minnesota, College of Veterinary Medicine. The goal of this initiative is to monitor the incidence and prevalence of relevant swine diseases in the US such as Porcine reproductive and respiratory syndrome (PRRS) or Porcine Epidemic Diarrhea (PED) for example. Participants are voluntarily sharing the health status of their farms in order to better understand, and in the future, control these illnesses. Each week participants receive a report including a one-page summary of a scientific fact of interest. From now on, the Science Page will be published on the blog here, every Friday.

This week’s edition

All of the previous Science Pages are compiled here.
If you want to know more about the Swine Health Monitoring Project, an article from the National Hog Farmer and one  from the Swine Health Information Center will give you an overview of the program and its goals.

 

Beneficial but variable effect of vaccination to control Salmonella in pigs

In this meta-analysis conducted by the Center for Veterinary Health Surveillance (Madrid, Spain) in collaboration with Drs. Conrado, Perez, and Alvarez from the University of Minnesota, the efficacy of vaccination to control Salmonella infection in pigs was evaluated. The meta-analysis reviewed a total of 44 studies focusing on Salmonella typhimurium or Salmonella choleraesuis. Included protocols were using either inactivated (killed) or live-attenuated vaccines.

Results showed that both vaccine types had a similar efficacy and that the most successful control strategies among the ones reviewed were using killed vaccines to control Salmonella choleraesuis.

Alvarez swine salmonella vaccine 2017

Abstract: Consumption or handling of improperly processed or cooked pork is considered one of the top sources for foodborne salmonellosis, a common cause of intestinal disease worldwide. Asymptomatic carrier pigs may contaminate pork at slaughtering; therefore, pre-harvest reduction of Salmonella load can contribute to reduce public health risk. Multiple studies have evaluated the impact of vaccination on controlling Salmonella in swine farms, but results are highly variable due to the heterogeneity in vaccines and vaccination protocols. Here, we report the results of an inclusive systematic review and a meta-analysis of the peer-reviewed scientific literature to provide updated knowledge on the potential effectiveness of Salmonella vaccination. A total of 126 articles describing the use of Salmonella vaccines in swine were identified, of which 44 fulfilled the inclusion criteria. Most of the studies (36/44) used live vaccines, and S. Typhimurium and S. Choleraesuis were the predominant serotypes evaluated. Vaccine efficacy was most often measured through bacteriological isolation, and pooled estimates of vaccine efficacy were obtained as the difference in the percentage of positive animals when available. Attenuated and inactivated vaccines had similar efficacy [Risk Difference = − 26.8% (− 33.8, − 19.71) and − 29.5% (− 44.4, − 14.5), respectively]. No serotype effect was observed on the efficacy recorded for attenuated vaccines; however, a higher efficacy of inactivated vaccines against S. Choleraesuis was observed, though in a reduced sample.

Results from the meta-analysis here demonstrate the impact that vaccination may have on the control of Salmonella in swine farms and could help in the design of programs to minimize the risk of transmission of certain serotypes through the food chain.

Link to the full article