Mycoplasma hyorhinis and Mycoplasma hyosynoviae dual detection patterns in dams and piglets

Today, we are sharing an original research article published by the MycoLab and Dr. Maria Pieters in PLOS One regarding detection patterns for 2 species of mycoplasmas in sows and piglets.

The objectives of this study were to:

  • describe when Mycoplasma hyorhinis and Mycoplasma hyosynoviae can be detected in piglets and is sows,
  • assess if there was a correlation between detection of the mycoplasmas in the sow and in the piglet, and
  • assess if there was a correlation between lameness and mycoplasma detection.


Under the conditions of this investigation, dams appeared to be consistently positive for both M. hyorhinis and M. hyosynoviae prior to weaning.

In contrast, higher detection was observed in piglets at week 3, in comparison to week 1 post-farrowing, with M. hyorhinis, while detection of M. hyosynoviae was remarkably minimal.

The relative risk of developing lameness in postweaning piglets was highly associated with the detection of M. hyorhinis at 3 weeks of age

This research article is available in open-access on the PlOS One website.


To answer their questions, researchers selected a 2,000 farrow-to-wean farm located in the Midwest with an unknown prevalence of the 2 mycoplasmas. 128 piglets were randomly selected from 30 sows, representative of the parity structure of the farm.

Swabs of the piglets and sows tonsils were taken 1 and 3 weeks post-farrowing. Starting at 5 weeks of age, piglets were evaluated for lameness every 2 weeks until they reached 22 weeks.

Tonsillar swabs were sent to the UMN VDL and were tested by PCR for Mycoplasma hyorhinis and Mycoplasma hyosynoviae.

Experimental design

Lameness scores were determined as follows: Score of 0) pig gets up immediately from a lying position and moves freely in the pen with balanced weight on all four limbs. Score of 1) pig rises immediately but a reluctant movement is observed, with short steps and uneven distribution of body weight. Score of 2) pig moves slowly in the pen with short steps and reduced weight in the sore limb, or pig rises slowly and the affected limb was not weight bearing. Score of 3) pig is reluctant to rise, with muscle shivering when standing and lifts the sore limb from the floor, or pig refuses to walk or walks on three limbs only and Score of 4) pig only rises when forced and when standing has marked signs of pain (e.g. reluctance to move, limping and vocalization).


Dams appeared to be consistently positive for both M. hyorhinis (72% positive) and M. hyosynoviae (72% and 55% of positive sows respectively at week one; 65% and 48.3% positive at week 3). On the other hand, M. hyorhinis and M. hyosynoviae were detected in a small proportion of piglets in week one (8.3% and 0% of piglets positive respectively). However, M. hyorhinis was detected in half of the sampled piglet population just prior to weaning whereas only 0.9% of them were positive for M. hyosynoviae.

Mycoplasmas detection percentages in tonsillar swabs

M. hyorhinis was detected in a higher proportion of first parity dams than in multiple parity dams in both weeks of sampling, although this difference was only significant on week 3 of sampling. Detection of M. hyosynoviae, however, was higher in multiple parity dams in the first week of sampling, yet an increase in PCR detection was observed in first parity dams in week 3. The pattern of increasing detection between weeks one and three post-farrowing observed for both microorganisms in first parity dams may reflect a more recent transmission event and consequent colonization.

PCR detection of mycoplasmas in parity 0 and older sows

The risk of developing lameness at least once during post-weaning was higher if the piglets were detected positive for M. hyorhinis at week three. Additionally, there was a significant association between positive detection of M. hyorhinis at week 3 and a positive lameness score during its post-weaning age.
However, the association between positive detection of M. hyosynoviae and lameness score in post-weaning was not established due to fewer numbers of positive cases in week three.


Mycoplasma hyorhinis and M. hyosynoviae are agents associated with arthritis in pigs. This study investigated the tonsillar detection patterns of M. hyorhinis and M. hyosynoviae in a swine population with a history of lameness. The plausibility of dual PCR detection of these agents in dams at one and three weeks post-farrowing and their offspring at the same time was determined. The association between M. hyorhinis and M. hyosynoviae detection in piglets and potential development of lameness in wean-to-finish stages was evaluated by correlating individual piglet lameness scores and PCR detection in tonsils. Approximately 40% of dams were detected positive for M. hyorhinis and M. hyosynoviae at both one and three weeks post-farrowing. In first parity dams, M. hyorhinis was detected in higher proportions (57.1% and 73.7%) at both weeks of sampling compared to multi-parity dams. A lower proportion of first parity dams (37.5%) were detected positive at week one with M. hyosynoviae and an increase in this proportion to 50% was identified in week three. Only 8.3% of piglets were detected positive for M. hyorhinis in week one compared to week three (50%; p<0.05). The detection of M. hyosynoviae was minimal in piglets at both weeks of sampling (0% and 0.9%). Lameness was scored in pigs 5–22 weeks of age, with the highest score observed at week 5. The correlation between PCR detection and lameness scores revealed that the relative risk of developing lameness post-weaning was significantly associated with detection of M. hyorhinis in piglets at three weeks of age (r = 0.44; p<0.05).The detection pattern of M. hyorhinis and M. hyosynoviae in dams did not reflect the detection pattern in piglets. Results of this study suggest that positive detection of M. hyorhinis in piglets preweaning could act as a predictor for lameness development at later production stages.

Morrison Swine Health Monitoring Project 2018 Summary

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, Dr Cesar Corzo shares the summary of the year 2018 for the Morrison Swine Health Monitoring Project.

During 2018 the MSHMP continued to make progress in different areas related to our main objective of developing the capacity to support the industry respond to emerging pathogens.

1) Database – Database has been structured to be able to capture a larger volume of data. This is a major step forward as we continue to work towards building the capacity of adding more sites and disease entities if needed.

2) Prospective PRRS sequence monitoring – The process of capturing diagnostic data continues, although not yet automated it is still adding sequences to the database. The database currently has 23,414 PRRS sequences from 20 systems and 21 states. Analyses of the database have begun with a subset but ultimately, we will be exploring trends and seasonal relationships involving spatialͲtemporal approaches. The database continues to provide a resource for MSHMP participants when conducting outbreak investigations.

3) Transport data capture and analysis – After a challenging year with our transport App we have decided to go back to basics and try a new approach to capturing transport data. The new approach which involves technology already validated in the trucking industry is currently being tested; we will follow up on this objective later this year.

4) Expansion – MSHMP continues to grow through three different ways:

  • 1) Current MSHMP participants continue to add new established farms,
  • 2) New participants have joined the project, two new production systems are already reporting and 2 more are in the process of providing data and
  • 3) Growing herd data inclusion into MSHMP has begun and is in the early stages as we learn how to link it with the breeding herd.

We have also continued our commitment with creating value to our producers through specific research projects that have been shared through conferences, MSHMP participant meeting during AASV and Leman Conference.

Peer Reviewed Publications

1. Vilalta C, Sanhueza J, Alvarez J, Murray D, Torremorell M, Corzo C, Morrison R. Use of processing fluids to determine porcine reproductive and respiratory syndrome virus infection status in pig litters. Vet Microbiol. 2018. 225:149Ͳ156. DOI: 10.1016/j.vetmic.2018.09.006

2. Machado, G., C. Vilalta, A.M. Corzo, C., Torremorrell, M., Perez, K. VanderWaal. Predicting outbreaks of Porcine Epidemic Diarrhea virus through animal movements and spatial neighborhoods. Nature Scientific Reports. Accepted.

3. Kinsley, A.C., A. Perez, M.E. Craft, K. VanderWaal. Characterization of swine movements in the United States and implications for disease control. Preventive Veterinary Medicine. Submitted.

4. Sanhueza JM, Vilalta C, Corzo C, Arruda AG. Factors affecting Porcine Reproductive and Respiratory Syndrome virus time-to-stability in breeding herds in the Midwestern United States. Transbound Emerg Dis. 2018. Dec 6. Doi: 10.11111/tbed.13091.

5. Arruda AG, Sanhueza J, Corzo C, Vilalta C. Assessment of area spread of porcine reproductive and respiratory syndrome (PRRS) virus in three clusters of swine farms. Transbound Emerg Dis. 2018. DOI: 10.1111/tbed.12875.

6. Arruda AG, Vilalta C, Puig P, Perez A, Alba A. Time-series analysis for porcine reproductive and respiratory syndrome in the United States. PLoS One. 2018. 13(4):e0195282. DOI: 10.1371/journal.pone.0195282. eCollection.

7. VanderWaal, K, Perez A, Torremorrell A, Morrison R, Craft M. Role of animal movement and indirect contact among farms in transmission of porcine epidemic diarrhea virus. Epidemics. 2018. 24:67-75. DOI: 10.1016/j.epidemic.2018.04.001.


We would like to acknowledge the strong team of faculty members, post-docs, students and staff that make this project possible. Additionally, this project would not be possible without the commitment of participants and practitioners and funding from the Swine Health Information Center.

Faculty: B. Morrison, C. Corzo, A. Perez, M. Torremorell, K. VanderWaal, J. Torrison and D. Linhares (ISU), D. Holtkamp (ISU), A. Arruda (OSU), and G. Machado (NCSU)

Post-Docs and Students: Carles Vilalta (Data visualization, PRRS testing), Juan Sanhueza (TTS, spatialͲtemporal analysis), Mariana Kikuti (PRRS sequence trends), Paulo Fioravante (IT Director), Emily Geary (Data manager), Kaushi Kanankege (Spatial analysis), Igor Paploski (Regional PRRS sequence analysis), Belinda Befort (Diagnostic trends)

Antimicrobial Resistance Projects: Towards Antimicrobial Stewardship

This article was written by Drs. CJ Gebhart, KE Olsen and JL Torrison from the Veterinary Diagnostic Laboratory, University of Minnesota.

The emergence of antimicrobial resistance in humans, animals and the environment is a major global public health threat to both human and veterinary medicine.  Efforts to address this important issue involve government, industry, academia, and most notably, veterinary diagnostic laboratories (VDLs).  These efforts include surveillance to assess the extent resistance in human and animal pathogens and the development of policies to monitor and control antimicrobial resistance.

A collaborative effort involving the stakeholders listed above is the key to addressing this emerging threat of antimicrobial resistance and VDLs play major roles in these collaborative efforts.  As reported in a Commentary by GK Hendrix in the Journal of Veterinary Diagnostic Investigation in 2018, VDLs are the “nexus in the battle against antimicrobial resistance” (1). The University of Minnesota VDL Bacteriology Section performs almost 30,000 bacterial cultures annually, and most of the pathogenic isolates are archived for future use.  These uses include further testing (subtyping, virulence gene assays, serotyping, etc.), use in disease control efforts (autogenous vaccines, etc.), various research projects, and surveillance studies.  Almost 5,000 of these pathogenic bacteria are subjected to antimicrobial resistance testing annually, and these antimicrobial minimum inhibitory concentration data are archived for decades for further use.

Performing one of many antimicrobial susceptibility tests in the University of Minnesota Veterinary Diagnostic Laboratory, Bacteriology Section.

For our part in this aforementioned collaborative effort in antimicrobial stewardship, the University of Minnesota VDL is actively involved in two collaborative government-organized antimicrobial resistance projects as well as several collaborative academic research projects on antimicrobial resistance.  The common goal of the collaborative government projects is to determine the population and distribution of resistant bacteria in the U.S. 

The first of these projects is the U.S. Department of Agriculture (USDA) Animal and Plant Health Inspection Service National Animal Health Laboratory Network (NAHLN) project (2).  This project has 19 AAVLD-accredited laboratories throughout the U.S. and Canada participating with the objective of monitoring antimicrobial resistance profiles in animal pathogens routinely isolated from VDLs.  Ultimately, this project will result in a national centralized data collection and reporting process, using harmonized methods and antimicrobial resistance interpretation and reporting standards.  It aims to monitor data for trends in antimicrobial resistance phenotypes (and eventually genotypes) by identifying new or emerging resistance profiles, monitoring usefulness of antimicrobials over time, and reporting these trends to facilitate antimicrobial stewardship efforts. 

This USDA project began in January, 2018, and initially involved collection of isolates and antimicrobial resistance data from Escherischia coli (all species), Salmonella enterica (all species), Mannheimia haemolytica (cattle) and Staphylococcus intermedius group (companion animals) from routine VDL submissions.  A target of about 3,000 isolates will be collected from the participating VDLs annually and archived for further testing.  The antimicrobial testing data will be tracked and stored by USDA for each isolate and an annual report will be prepared for stakeholders.  This report will include antimicrobial resistance trends for antibiotics important for human and animal health and the distribution of minimum inhibitory concentrations for each antimicrobial monitored for each bacterial pathogen for each animal species included in the study.

The second of these collaborative antimicrobial resistance projects is the Food and Drug Administration (FDA), Center for Veterinary Medicine, Veterinary-Laboratory Investigation and Response Network (Vet-LIRN) project (3). This project has 21 AAVLD-accredited laboratories participating with the objective of performing surveillance of antimicrobial susceptibility testing results and whole genome sequencing of pathogens from the National Antimicrobial Resistance Monitoring System scope of interest (4). 

This FDA project began in January, 2017, and initially involved collection of isolates and data for three zoonotic bacterial pathogens, with several other bacterial species added to the project in July, 2018.  About 2,000 isolates have been collected since project inception, and the FDA has randomly selected about 200 of these isolates for whole genome sequencing.  The remaining isolates have been archived for future studies.  As an additional benefit related to this project, the University of Minnesota VDL received funds from FDA to purchase an Illumina iSeq Sequencer and participate in a collaborative project designed to increase the number and capabilities of network laboratories involved in the whole genome sequencing portion of this FDA project.  Standardization and harmonization of these bacterial genome sequencing abilities among participating laboratories is further designed to increase the network capacity and facilitate future outbreak investigations.

In summary, in support of antimicrobial stewardship efforts, the University of Minnesota VDL Bacteriology Section provides clinical isolates and antimicrobial susceptibility testing data for two collaborative government-initiated projects, one in collaboration with the USDA and the other with the FDA.  Further, the VDL as a whole provides leadership in antimicrobial stewardship on a daily basis, cooperating with disease outbreak investigations, collaborating with academic and industrial researchers, and educating veterinarians, clients and the public on issues of antimicrobial stewardship (1).


1.  Hendrix, GK. 2018.  The Role of Veterinary Diagnostic Laboratories in the Fight Against Antimicrobial Resistance

2.  USDA. 2018. USDA’s Role in Combatting Antimicrobial Resistance. 

3.  FDA. 2018.  Veterinary Laboratory Investigation and Response Network

Project Invitation: Assessing within-herd PRRS variability and its impact on production parameters

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, Dr. Arruda and her numerous collaborators invite you to participate in a project.

We know that PRRS virus mutates and evolves quickly. We know there can be co-circulation of PRRS variants in a herd, and even within a single animal. We don’t know whether that can impact health and production. We don’t know how that affects the way we are currently sampling and assessing virus similarity within herds over time.

Project main goal:

This project aims to examine within-herd PRRSV variability over time for sow and growing pig sites under different PRRS immunity strategies (vaccinated, negative and positive herds), and investigate the association between within-herd PRRS variability and health and production parameters of interest to swine producers. We partnered up collaborators with a wide range of expertise to use whole genome sequencing (WGS) to provide insights on the likelihood of PRRS outbreaks

Objective 1:

Describe PRRSV quasispecies within farms using a sample of farms of different demographic types and PRRS management strategies over a one-year time span; and investigate whether PRRSV variability has an impact on health and production outcomes.

Objective 2:

Investigate and compare the use of WGS and different ORFs to determine the best predictor to identify and relate viruses within swine herds.

Objective 3:

Correlate PRRSV variants with production and disease metrics being due to “normal” within-herd virus evolution, vs. new PRRS introductions. And we will also look into the effect of PRRSv variants in production


We are looking to enroll 6 farms for this project, that has a duration of 1 year:

3 breeding herds (farrow-wean):

  • 1 “naïve” herd (no PRRS for at least last 2 years) that just had an outbreak (farm will be enrolled as a new outbreak happens)
  • 1 “vaccinated” herd (a herd that had a PRRS outbreak and has been vaccinated since then at least twice a year with a MLV)
  • 1 “naturally exposed” herd (a herd that had an outbreak in the past year but is no longer exposing or vaccinating animals (herd will be still eligible if gilts are exposed off site and brought in after testing negative)

3 growing pig herds (finisher or wean-finish):

  • 1 “naïve” herd (no PRRS for at least last 2 years) that just had an outbreak (farm will be enrolled as a new outbreak happens)
  • 1 “vaccinated” herd (a herd that vaccinates each batch of animals using a MLV)
  • 1 “positive” herd (a herd that had an outbreak in the past and is regularly exposed to live virus or a herd that is receiving known positive pigs from a positive source.

We would work with your veterinarian and your team to coordinate the submission of ~16 samples total in a monthly basis for 1 year (12 samplings). These samples will include a combination of processing fluids, oral fluids, and tonsil scrapings. All samples will be sent to the University of Minnesota monthly. Diagnostics is paid. Also, sharing production data will be a requirement.

Best of Leman 2018 series #3: J.Angulo – Understanding PRRSV infection dynamics in growing pigs in control and elimination programs

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

We can find all of the presentations selected from last year’s conference on the blog here.

Our third presentation for this year is from Dr. Jose Angulo from Zoetis and Dr. Paul Yeske from Swine Vet Center regarding PRRS infection dynamics in growing pigs.

Click on the image below to see his presentation at the conference:

African Swine Fever: economics versus pathology

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, Dr. John Deen compares the consequences of African Swine Fever based on its pathogenicity and its economic impact on the swine industry.


  • The disease appears to be relatively easy to identify, control and eradicate in the US
  • Introduction of African Swine Fever (ASF) would result but relatively few infected pigs
  • The immediate loss of export markets would nonetheless result in catastrophic economic losses

The establishment of ASF in pig populations in Eastern Europe and China has significantly increased the likelihood of the introduction into the US pig population. Its ability to survive for long times in a variety of materials, including pork products, makes it a real threat to travel the distance and infect US pigs. Indeed, with the trillions of ASF viral particle already produced, it is not hard to imagine that one or more of them has already found its way to North America, but subsequently did not find its way into a pig.

The multiple effects of Emerging Infectious Diseases (EID’s), especially hemorrhagic diseases such as ASF, have been mostly studied in human populations, but many of the generalities are appropriate in our preparations.Over the past 9 years the University of Minnesota’s College of Veterinary Medicine has led efforts in capacity building in USAID’s Emerging Pandemic Threats program of USAID. This, in turn, was part of the a broader set of efforts called the Global Health Security Agenda, which expends billions of dollars annually to control and prevent diseases such as MERS, Ebola and SARS.

In negotiating, planning and implementing strategies I came to a number of realizations, but a few came up repeatedly.The first is that population or public health is in short supply in many parts of the world. It is a central part of our swine medicine, but those thought processes are often not evident in human medicine, outside agencies such as the CDC.Many countries lack the luxury of such capabilities, both for human and veterinary medicine. Many countries are dependent on international collaboration, and such veterinary collaborations are underfunded.

The other major lesson is that people rarely act rationally in the face of potential epidemics. The combination of fear, rumors, misinformation and ignorance results in damage that goes far beyond the costs of the disease and its control. Economies are often severely affected, with fear driving a restriction in commerce, tourism and even basic policing.The resultant or exacerbated poverty can result in as much of an insult on health as the infectious disease of concern.

A challenge with the introduction of ASF, or any novel reportable disease, into the US swine herd is that we have a good idea on the behavior of the disease. Frankly, there are many diseases in our pigs that are more difficult to control. ASF moves relatively slowly and can be putatively recognized through its and excellent capabilities to isolate, trace and eradicate the disease. We lack, mostly, the major risk factors of feeding food products and backyard herds. The one concern is our extensive feral pig population, but concerted methods to reduce that exposure are available.

Inasmuch as we understand the behavior of the disease, the behavior of farmers, governments, business and farmers are more difficult to predict. With a loss of 25% of the market (plus any exports in transit being returned), those farmers dependent on public price discovery face the prospect of having no market. The devaluation of inventory and farms will result in decreased ability to finance operations.One or more farms will be affected directly by an ASF infection with rapid depopulation. If more farms are close to the infected farms, they too will be depopulated. However, for some time all farms will be severely affected by the elimination of export markets. Transport, especially between states, will often be stopped. Pigs will back up on the farms, with those that go to slaughter being highly devalued. Money for feed, disease control and other inputs will be hard to secure. Payrolls will not be met and employees will look for more promising jobs in other industries.

Much of our planning has been on disease readiness, and rightly so, as the speed and competence in which the disease is brought under control will determine the speed under which markets will be reacquired. Markets are quick to shut down borders and slow to open them. Most scenarios have regaining of all historic markets measured in years, however.Thus, we not only need disease management but supply management. The economics of pig production are brutal, with oversupply resulting in what can be described as death matches, with the survivors also compromised by the times of low prices and the industry stripped of many of its capabilities.

The industry is now completing many simulations of disease management in the face of the identification of pigs infected by ASF in the US.Depopulation to control disease is readily discussed and modelled to regain markets. Beyond this purpose, depopulation and restriction of production is often ignored, but it may be as important to regain market equilibrium and perhaps even price discovery. For the aggregate industry, there is real benefit to create strategies to combine the benefits of both, actively depopulating all potential contacts, not only through location but also through transportation and management networks.

A term in human health management is the “social determinants of disease”. Of these social determinants, none looms larger than poverty.In the same way, we need to recognize that disease affects economics, but economics also affects disease. Competent and invested care is best delivered on farms that are financially healthy. A rapid restabilization of the industry serves not the owners and employees, but also pigs and the public.