The UMN CVM students did a fantastic job at the 2018 American Association of Swine Veterinarians (AASV) meeting last week. Zhen Yang presented an update on his research regarding PCV3 and got the second place in the student oral competition.
Taylor Homann received a prize for her poster presentation. Marjorie Schleper was awarded one of the 10 student scholarships given by Merck Animal Health. Hunter Baldry was recognized for the most downloaded podcast: her interview of Dr. Clayton Johnson.
Lastly, Dr. Juan Sanhueza received one award given by Boehringer Ingelheim to advance the research on swine respiratory pathogens for his project: “Evaluation of parity as a delaying factor to reach PRRSv stability in sow farms”. Dr. Perle Boyer received a research grant from the AASV Foundation to develop Day 1 competencies for swine veterinary graduates.
In this study conducted by Dr. Sun during her PhD under the direction of Dr. Peter Davies, 66 swine veterinarians were sampled via nasal swabs every month for 18 months. Swabs were first cultured to detect Staphylococcus aureus and to determine the strains susceptibility (or resistance) to methicillin, and then were characterized by spa typing and MultiLocus Sequence typing (MLST). Click on the banner below to read the publication in open-access.
S. aureus monthly prevalence ranged from 58% to 82% and MRSA ranged between 6% and 15%. Those results were higher than the ones for the US population. 52% of the swine veterinarians were classified as persistent carriers, meaning that their samples came back positive for S.aureus at least 80% of the time, 47% were intermittent carriers. 21% of the veterinarians were true persistent carriers meaning that the same spa type of S.aureus was recovered each time the sample was positive.
Whole genome sequencing showed that strains isolated at the beginning and at the end of the study were similar genetically. Comparing spa types, 83% of all isolates belonged to a type also present in swine.
People working with pigs are at elevated risk of harboring methicillin resistant S. aureus (MRSA) in their nose, which is attributable to occupational exposure to animals harboring livestock adapted S. aureus. To obtain insight into the biological nature of occupationally related nasal culture positivity, we conducted a longitudinal study of 66 swine veterinarians in the USA.
The study cohort resided in 15 US states and worked predominantly with swine. Monthly for 18 months, participants self-collected nasal swabs and completed a survey to report recent exposure to pigs and other animals; the occurrence of work related injuries; and any relevant health events such as skin and soft tissue infections or confirmed staphylococcal infections. Nasal swabs were cultured using selective methods to determine the presence of MRSA and methicillin susceptible S. aureus (MSSA), and isolates were characterized by spa typing and MLST.
Prevalences of S. aureus (64%, monthly range from 58 to 82%) and MRSA (9.5%; monthly range from 6 to15%) were higher than reported for the US population (30% and 1.5% respectively). Predominant spa types were t034 (ST398, 37%), t002 (ST5, 17%) and t337 (ST9/ST398 13%), a distribution similar to that found in a concurrent study in pigs in the USA. Veterinarians were classified into three groups: Persistent carriers (PC, 52%), Intermittent carriers (IC, 47%) and Non-carriers (NC, 1%). Persistent carriage of a single spa type was observed in 14 (21%) of participants, and paired (first and last) isolates from PC subjects had minor genetic differences. Swabs from PC veterinarians carried higher numbers of S. aureus. Among IC veterinarians, culture positivity was significantly associated with recent contact with pigs.
Exposure to pigs did not lead to prolonged colonization in most subjects, and the higher numbers of S. aureus in PC subjects suggests that unknown host factors may determine the likelihood of prolonged colonization by S. aureus of livestock origin. Exposure to S. aureus and persistent colonization of swine veterinarians was common but rarely associated with S. aureus disease.
We are trying to give you a daily update on the situation regarding the auto accident that happened in Prague on Tuesday and lead to Dr. Morrison’s passing.
As of today, Jeanie Morrison, Dr. Morrison’s wife, is no longer in a life-threatening condition said the doctors in charge of her recovery. We do not have any further information but the Morrison family is in the process of creating a online information page to provide updates on Jeanie’s situation. We will add the link here when it is available.
Mycoplasma hyorhinis can cause polyserositis and arthritis in post-weaning pigs.
To study M.hyorhinis‘ prevalence based on age, nasal swabs were taken from pigs at 1, 7, 14, 21, 28, 35, 42, 49, 56, 63, 70 and 77 days as well as from sows, in 3 different Minnesotan herds (A, B, and C).
8.8% of the sows were positive for M.hyorhinis in herds A and B whereas 3.3% of the sows were positive in herd C.
The percentage of positive piglets (<21 days of age) was low: between 0 and 10% depending on the herds.
At 28 days of age, the prevalence of M.hyorhinis in pigs increased dramatically to around 50% in herd A and 100% in herd B. After 42 days of age, the prevalence in those herds stayed above 95%.
The prevalence in herd C stayed close to 0% until the pigs reached the age of 77 days, time at which the prevalence increased to 100%.
Mycoplasma hyorhinis is one of the causative agents of polyserositis and arthritis in postweaning pigs. Knowledge regarding colonization frequency and age distribution in modern pig production is lacking. The objective of this study was to estimate the prevalence of M hyorhinis colonization in different age groups across three commercial pig populations. Nasal swabs were collected from sows, piglets and nursery pigs of different ages. Oral fluids were collected from nursery pigs. Necropsies were performed to assess the presence of M hyorhinis-associated disease. M hyorhinis was detected in 5/60 sows in herd A, 3/60 in herd B and none in herd C. In herd A and B, the prevalence was low in preweaning piglets (∼8 per cent) and high in postweaning pigs (∼98 per cent). A total of 7/8 oral fluids tested PCR positive in herds A and B, while 1/8 tested positive in herd C. In herd C, the preweaning and postweaning prevalence was low. In herds A and B, necropsied pigs had polyserositis lesions where M hyorhinis was detected by PCR. This study showed that prevalence of M hyorhinis colonization varies with pig age and across farms. Information generated will aid in the design and implementation of control and prevention strategies.
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:
Using different diagnostic tests:
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.
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.
Swine and poultryviruses, such as porcine reproductive and respiratory syndrome virus (PRRSV), porcine epidemic diarrhea virus (PEDV), and highly pathogenic avian influenza virus (HPAIV), are economically important pathogens that can spread via aerosols. The reliability of methods for quantifying particle-associated viruses as well as the sizedistribution of aerosolized particles bearing these viruses under field conditions are not well documented. We compared the performance of 2 size-differentiating airsamplers in disease outbreaks that occurred in swine and poultry facilities. Both airsamplers allowed quantification of particles by size, and measured concentrations of PRRSV, PEDV, and HPAIV stratified by particle size both within and outside swine and poultry facilities. All 3 viruses were detectable in association with aerosolized particles. Proportions of positive sampling events were 69% for PEDV, 61% for HPAIV, and 8% for PRRSV. The highest virus concentrations were found with PEDV, followed by HPAIV and PRRSV. Both air collectors performed equally for the detection of total virus concentration. For all 3 viruses, higher numbers of RNA copies were associated with larger particles; however, a bimodal distribution of particles was observed in the case of PEDV and HPAIV.
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.