Science Page: Prevalence comparison among different MSHMP cohorts

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 the MSHMP team regarding the differences in PRRS prevalence among various cohorts.

Key points:

  • Prevalence among cohorts does not differ.
  • Seasonal patterns can be seen in different cohorts located in different regions.

Prevalence PRRS status cohortA comparison from a prevalence standpoint between the cohort of farms belonging to the 13 systems participating at the start of the MSHMP (CS) and the cohort of farms from systems that joined the program later (CL), was performed with the objective of assessing whether the patterns between cohorts compare.

As seen in Figure 1–CS, there was a clear shift towards more use of MLV over LVI for sow herd stability purposes. The proportion of farms using LVI in the CS versus the CL is 5% and 10%, respectively. When assessing the proportion of farms in each AASV PRRS category (Holtkamp et al., 2011) both groups are comparable (Table 1). Also the temporal pattern of infection can be seen in both cohorts as described by Tousignant et al (2014).

In summary, both cohorts of farms (CS versus CL) yield similar results which continue to highlight the robustness of the program and the representativeness of the systems contributing to this program.

NHF: Processing fluids are effective for PRRSV diagnostics

This month in the National Hog Farmer, Drs. Carles Vilalta, Juan Sanhueza, and Montse Torremorell share a project instigated by the late Dr. Bob Morrison regarding the use of processing fluids to make a PRRSV diagnosis.

The improvement of sampling and diagnostics techniques has made sampling on the farm an easier task with the use of pooled serums or oral fluids samples for example.

One of the ways to get cheaper, more sensitive and quicker techniques would be to use routine chores, such as piglet processing, since castration and tail docking are part of the regular procedures in sow farms.

The goal of this study was to evaluate the accuracy of the processing fluids (the liquid accumulated at the bottom of the pail when farmers collect tails and testicles during routine procedures) by real-time polymerase chain reaction to assess PRRSV status in a sow herd.

The key points from the studies were:


Bioaerosol sampling for airborne virus surveillance in swine facilities

Bioaerosol sampling refers to the methods by which one is able to collect the particles of biological origin (microbial, animal, or plant) in the air. This is useful information in swine production because many economically important pathogens can be transmitted by air from one farm to the next. 73 scientific reports were included in this review published in the journal Frontiers in Veterinary Science. The information regarding the presence of viruses in the air around swine settings is limited but their findings has been compiled in the figure below. Overall, bioaerosol sampling could be a promising way to conduct non-invasive viral surveillance among swine farms.

Viruses detected in radisuses around farms
Influenza A, PRRSV, PEDV detection downwind from farms with infected source populations


Modern swine production facilities typically house dense populations of pigs and may harbor a variety of potentially zoonotic viruses that can pass from one pig generation to another and periodically infect human caretakers. Bioaerosol sampling is a common technique that has been used to conduct microbial risk assessments in swine production, and other similar settings, for a number of years. However, much of this work seems to have been focused on the detection of non-viral microbial agents (i.e., bacteria, fungi, endotoxins, etc.), and efforts to detect viral aerosols in pig farms seem sparse. Data generated by such studies would be particularly useful for assessments of virus transmission and ecology. Here, we summarize the results of a literature review conducted to identify published articles related to bioaerosol generation and detection within swine production facilities, with a focus on airborne viruses. We identified 73 scientific reports, published between 1991 and 2017, which were included in this review. Of these, 19 (26.7%) used sampling methodology for the detection of viruses. Our findings show that bioaerosol sampling methodologies in swine production settings have predominately focused on the detection of bacteria and fungi, with no apparent standardization between different approaches. Information, specifically regarding virus aerosol burden in swine production settings, appears to be limited. However, the number of viral aerosol studies has markedly increased in the past 5 years. With the advent of new sampling technologies and improved diagnostics, viral bioaerosol sampling could be a promising way to conduct non-invasive viral surveillance among swine farms.

Link to the full article