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.
Cumulative incidence of PED and PDCoV in Canada is decreasing according to data coming from the industry for the year 2014, 2015 and 2016.
PED showed a cyclical pattern when looking at the number of farms infected. However, PDCoV showed a more erratic pattern with no clear trends.
Industry driven disease control programs provide useful information to understand temporal evolution and disease patterns.
The primary goal of this study was to estimate herd-level incidence and prevalence measures for PEDV and PDCoV in swine herds in Ontario (Canada) between January 2014 and December 2016, based on industry data (Ontario Swine Health Advisory Board (OSHAB) Disease Control Program (DCP)).
The full paper was published in the Transboundary and Emerging Diseases journal.
Herd-level incidence risk and rate of two novel porcine coronaviruses (PEDV and PDCoV) in Ontario swine herds between 2014 and 2016, and estimated prevalence of positive cases at the end of each year based on data provided in the Ontario Swine Health Advisory Board (OSHAB) Disease Control Program (DCP) database (average number of herds for 2014–2016 = 1093).
PED showed a cyclical pattern over the three years of the study while PDCoV showed a more erratic pattern. Incidence decreased over time between 2014 and 2016 in both, PED and PDCoV.
Thank you for supporting our bid to host the 2022 IPVS in Minneapolis. Unfortunately, Minneapolis was not selected and the 2022 IPVS meeting will take place in Leipzig, Germany.
We are grateful about the experience this has represented for us, the words of encouragement we have received from many of you and we remain excited about bringing forward a bid for IPVS 2024 in a couple of years at the 2020 IPVS in Brazil. We hope we can count on your support.
Veterinary students: Are you shadowing a swine practitioner this summer or have you been involved in an interesting clinical case investigation? Did you work on your veterinary skills by designing a differential diagnosis list or working on a treatment plan? Did you investigate a problem by analyzing production records? Share your work at the Allen D. Leman Swine Conference to win the Morrison Swine Innovator Prize!
The Allen D. Leman Swine Conference is organizing a session for veterinary students to demonstrate their problem-solving skills through the presentation of a case or experience where students challenged their clinical training and problem-solving capabilities necessary for day-to-day practice. Creativity and originality in the support and delivery are encouraged. The session will take place on Sunday at the Allen D. Leman Swine Conference and will include presentations from pre-selected veterinary students. Invited students will also be part of a dedicated workshop to enhance their leadership and communication skills, networking opportunities, and will receive a $1,000 stipend, free admission to the Leman Swine Conference, a copy of the Diseases of Swine book (10th edition), and of course the winner of the Morrison Swine Innovator Prize will receive a substantial monetary prize.
Attending the Leman Conference is a great opportunity for veterinary students who want to network with industry leaders. Submissions to enter in the selection to present at the DVM student session at the Leman Conference should be uploaded at z.umn.edu/MSIP by August 15th at the end of the day.
If you have any questions, please contact Dr. Perle Boyer at pboyer@umn.edu. For more information about the Morrison Swine Innovator Prize visit z.umn.edu/MSIP.
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.
Porcine Deltacoronavirus (PDCoV) was first reported in the US in 2014.
Monitoring of PDCoV cases showed that it is still present in pig herds from the United States.
PDCoV testing and reporting must continue in order to increase our understanding of the disease.
Porcine Deltacoronavirus (PDCoV) was first detected in the US in 2014. The complete genome of a United States’ PDCoV isolate was characterized by Marthaler et al. (2014), which was ~99% similar to a virus detected in Hong Kong.
Clinical signs may be similar to Porcine Epidemic Diarrhea (PED) and Transmissible gastroenteritis coronavirus (TGEV), including acute diarrhea, mild to moderate vomiting, and ultimately death especially in neonatal pigs.
PDCoV continues to be present in the United States swine herd. Since March, 2017 PDCoV cases have been passively reported to MSHMP. Over this period of time, 37 cases have been reported by six participant systems.
Monthly number of PDCoV cases since March 2017
Since November 2017, 24 PDCoV cases were communicated to MSHMP, representing 67% of the reported cases.
PDCoV still occurs in the US at an apparent low number of reported cases. Swine producers and veterinarians must stay vigilant for clinical signs compatible with PDCoV and continue to test for this pathogen.
Today we are sharing a publication from the Torremorell lab regarding the impact of vaccination (both homologous and heterologous) on the detection of swine influenza virus in aerosols. The full publication is available in open access online on the PlosOne website.
Influenza A virus can be transmitted by direct and indirect contact and aerosols. Indeed, the virus has been detected and isolated from aerosols generated from pigs with and without immunity. Since then, there has been increased evidence of the role of aerosols in influenza transmission among swine.
Vaccination is used in swine populations as a strategy to mitigate clinical effects and the economic impact of influenza infections. It has also been proven to reduce shedding in pigs. Additionally, a study on the transmission of influenza in ferrets showed that high temperature may decrease the risk of airborne transmission. Therefore, we wondered if combining vaccination and high temperature would affect the detection of influenza virus in the air.
The objective of this study was to assess the effect of vaccination on the generation of influenza A virus bioaerosols under warm conditions in pigs with varying degrees of cross-protective immunity.
Material and Methods
36 pigs of three weeks of age, seronegative for influenza were separated into four groups:
vaccinated with an influenza strain identical to the one used for the challenge (homologous)
vaccinated with a commercial vaccine containing multiple strains of influenza, all different from the challenge strain (heterologous, multivalent)
vaccinated with a commercial vaccine containing one influenza strain different from the challenge strain (heterologous, monovalent)
unvaccinated, which received an injection of saline instead
Pigs were challenged intranasally and intratracheally with a strain of H1N1 influenza virus, two weeks after the last vaccination.
Serum collected the day prior to the vaccination and at the end of the study 14 days post inoculation were tested via hemagglutination inhibition (HI) and ELISA.. Nasal swabs and oral fluids were collected and tested via PCR. Air samples were collected three times a day and tested via PCR and virus isolation. Temperature and humidity were recorded every five minutes.
Results
Hemagglutination inhibition and ELISA
Prior to infection, pigs in group 1 (Vaccinated, homologous) had significantly higher HI titers compared to the other three groups. In the group 3 (vaccinated, heterologous monvalent) 4 pigs had HI titers against the challenge strain, while pigs in groups 2 and 4 were negative against the challenge strain. All groups were HI positive against the challenge strain at necropsy, however HI titers were statistically different between group 4 and groups 1 and 3.
Proportion of pigs infected
The proportion of pigs infected was significantly higher in group 4 than in the vaccinated ones. Also, the percentage of infected pigs in group 1 was significantly lower than in group 2, but there was no difference with group 3.
Proportion of negative pigs over time
Nasal swabs and oral fluids
Pigs in group 4 had higher amounts of nasal virus shedding most of the sampling days compared to vaccinated groups. Additionally, group 2 had higher levels of IAV compared with groups 1 and 4. Oral fluid results were in agreement with nasal swab.
Nasal shedding over time
Air samples
All air samples in the vaccinated groups tested negative by RRT-PCR. Air samples collected at days 1, 2 and 3 from NON-VAC pigs tested positive by RRT-PCR but negative by virus isolation
Abstract
The 2009 influenza pandemic, the variant H3N2v viruses in agricultural fairs and the zoonotic poultry H5N9 infections in China have highlighted the constant threat that influenza A viruses (IAV) present to people and animals. In this study we evaluated the effect of IAV vaccination on aerosol shedding in pigs housed in warm environmental conditions. Thirty-six, three-week old weaned pigs were obtained from an IAV negative herd and were randomly allocated to one of 4 groups: 1) a homologous vaccine group, 2) a heterologous multivalent vaccine group, 3) a heterologous monovalent group and, 4) a non-vaccinated group. After vaccination pigs were challenged with the triple reassortant A/Sw/IA/00239/04 H1N1 virus. Environmental temperature and relative humidity were recorded throughout the study. Nasal swabs, oral fluids and air samples were collected daily. All samples were tested by RRT-PCR and virus isolation was attempted on positive samples. Average temperature and relative humidity throughout the study were 27°C (80°F) and 53%, respectively. A significantly higher proportion of infected pigs was detected in the non-vaccinated than in the vaccinated group. Lower levels of nasal virus shedding were found in vaccinated groups compared to non-vaccinated group and IAV was not detected in air samples of any of the vaccinated groups. In contrast, positive air samples were detected in the non-vaccinated group at 1, 2 and 3 days post infection although the overall levels were considered low most likely due to the elevated environmental temperature. In conclusion, both the decrease in shedding and the increase in environmental temperature may have contributed to the inability to detect airborne IAV in vaccinated pigs.
