Swine Veterinary Report – Q1 2023
Ontario Animal Health Network (OAHN) Swine Network Quarterly Veterinary Report
Disease Surveillance Discussion
PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME (PRRS)
On the clinical impressions survey 50 % of practitioners indicated that PRRS had increased in the breeding herd in Q1 compared to Q4 and 50% of practitioners indicated increased PRRS in the growing herd in Q1 compared to Q4. One practitioner commented that 30 % of sow herds that they worked with had been infected with a new strain of PRRS over the winter months.
PORCINE EPIDEMIC DIARRHEA (PEDV) / PORCINE DELTACORONAVIRUS (PDCoV)
Jessica Fox, Manager at Swine Health Ontario reported that the overall incidence has been low in comparison to previous winters. The following cases were reported in Q1 2023:
Jan 18, 2023 Perth PED Nursery-to-finish
Jan 18, 2023 Oxford PED Farrow-to-wean
Mar 31, 2023 Bruce PED Finisher
Jessica also reported that there have been 2 additional cases in Q2 2023 thus far.
Apr. 6, 2023 Bruce PDCoV Finisher
Apr. 14, 2023 Oxford PED Farrow-to-wean
The PED and PDCoV Tracking map is available at the Swine Health Ontario website and shows current and annual cases by county. http://www.swinehealthontario.ca/Disease-Information/PED-PDCoV-Tracking-Map
INFLUENZA A (IAV)
Ninety-three percent of practitioners ranked the frequency for IAV as common (50%) or very common (43%). At the Animal Health Laboratory, the following genotypes were identified in 41 submissions in Q1 2023: Subtype H1N1 classical = 2 with 0 alpha, 1 beta, 1 gamma. Subtype Pandemic H1N1= 3. Subtype H3N2 = 14. Subtype H1N2 = 15 with 2 cluster Ivb and 2 cluster Ivx and 11 untypable by cluster. There was only 1 case with 2 or more subtypes in a single case (H1N2 +H3N2). Gallant Laboratories reported isolating H1N2 (0), H3N2 (2) and H1N1 (0.)
Based on the clinical impression survey 50% of practitioners reported an increase in cases of erysipelas over Q4. One practitioner commented that they had an acute break in a finisher. The clinical impression of an increased frequency of erysipelas over Q4 is consistent with a seasonal pattern of increased carcass condemnations due to erysipelas during Q4 and Q1 in comparison to Q2 and Q3.
Dr. Delay reported that that there were no further cases of Brachyspira hampsonii detected at AHL. Total cases of B. hampsonii confirmed by laboratory diagnostics in Ontario is 2 cases. The first case was in Q3 2020. There are reports of increased numbers of cases of B. hampsonii in Quebec in previous quarters. Some of these infections have been difficult to eliminate from the herd.
Swine Disease & Syndromic Surveillance
Dr. Hannah Golightly summarized findings from swine disease and syndromic surveillance activities for Q1 2023
Influenza Type A (IAV)
For each disease, weeks are identified as signals if the number of positive submissions is 3 standard deviations beyond the calculated baseline. The following IAV signals were detected in Q1 2023:
- Week 9 (Feb 26 to Mar 4) – Coughing or respiratory clinical signs in various stages of production (1x suckling, 3x nursery, 2x grow finish) with 3x H1N2, 1x H3N2, 1x H1N1, and 1x H3
- Week 12 (Mar 19-25) — Coughing or respiratory clinical signs in various stages of production (1x sow, 2x suckling, 1x nursery, 2x grow finish) with 5x H1N2, 1x H3N2
Over the last year H3N2 (34.8 %) has been the dominant IAV subtype but has been followed closely by H1N2 (28.9 %) and then H1N1 (11.1 %). The category of partial subtypes (15.6%) has declined slightly since Q4 2022. These patterns ebb and flow from one quarter to the next. In Q1 2023 the number of cases with H3N2 (34.2 %) and H1N2 (34.2 %) were equal.
The following Salmonella signals were detected in Q1 2023:
- Week 2 (Jan 8-14): 4 x nursery with clinical signs and involving identification of Salmonella uganda, Salmonella typhimurium, Salmonella cholerasuis*, and 2x Salmonella I:4,,12:i:-
- Week 10 (Mar 5-11): 2x nursery, 1x GF, with clinical signs and involving Salmonella I:4,,12:i:-, Salmonella litchfield, Salmonella derby, and Salmonella newport
*Note: The Salmonella cholerasuis is most likely originating from a Salmonella vaccine as Salmonella cholerasuis has not been a clinical issue in Ontario for many years.
There were no syndromic signals detected in Q1 2023.
Animal Health Laboratory Diagnostic Reports
Dr. Delay provided an update on AHL activity in Q1 2023
A total of 1328 swine cases, representing all test types, were submitted to the AHL during 2023 Q1. Of these, 97 cases had a pathology component (gross post-mortem and / or histopathology) and originated from commercial herds. Three (3) additional pathology cases were from pet pigs, and there were 2 meat inspection cases. One (1) case was from a smallholder herd.
For pathology cases, the PID inclusion rate in Q1 improved to 78%. Age or commodity group was provided for 100% of cases, and adequate clinical history was provided for 98% of cases. Thank you for your cooperation!!
Notable pathogens or disease syndromes detected and apparent trends identified during 2023 Q1 are as follows:
All swine cases:
- PRRSV- and influenza A virus-positive case numbers are mildly increased over the previous quarter and are similar to 2022 Q1.
- Rotavirus-positive cases are mildly increased over the previous quarter, with 48 cases, and case numbers are similar to those in 2022 Q1. There is a trend in the most recent 2 quarters for more frequent detection of rotavirus C compared with rotavirus A.
- Brachyspira hyodysenteriae was detected in 2 cases.
- Brachyspira murdochii was detected in 1 case. This organism is of low pathogenicity in pigs and can cause clinical or subclinical colitis at the grow-finish stage.
- Actinobacillus pleuropneumoniae was isolated in an increased number of cases. There were 5 cases in Q1 compared with 2 cases in both Q4 and Q1 2022.
- Erysipelothrix rhusiopathiae was isolated from 1 case. This was a pet pig.
- Although PCV2 and PCV3-positive case numbers remain high with 49 and 62 cases respectively, the number of cases with potentially significantly low Ct values and / or IHC-positive status remains low with only 4 PCV2 cases and 1 PCV3 case.
- Glaesserella australis was isolated from lung and pericardial swab samples from 2 cases. This is a first identification in Ontario. This organism has caused health issues in Australia that are similar to Actinobacillus pleuropneumonia. Plans are to continue monitoring this organism.
Swine pathology cases:
- Porcine sapovirus was detected in 2 cases including suckling and nursery pigs and was associated with diarrhea in 1 case (suckling pigs). Sapovirus PCR was positive, with low Ct values, from intestinal content in both cases, although only the suckling piglets had histologic lesions of atrophic enteritis. Porcine sapovirus in situ hybridization (ISH) in the suckling pigs confirmed co-localization of PSV with intestinal lesions.
- Porcine parainfluenza virus 1 and porcine astrovirus 4 were detected (1 case each) by PCR in lung from nursery pigs with interstitial pneumonia (PI-1) and in suckling pigs with necrotizing and suppurative bronchiolitis (PoAst-4). PoAst-4 nucleic acid was identified by ISH in injured small airway epithelium.
Gallant Custom Laboratory Diagnostic Reports
Anna Pietruszkiewicz reported on the highlights of the 13 cases submitted to Gallant Labs from Ontario in Q1 2023. This represents a decrease in the number of isolates in comparison to Q4 2023.
- Strep suis was identified with increased frequency with 7 cases in Q1 2023 compared to 4 cases in Q4 2022. There were a similar number of cases (6) of Strep suis in Q1 2022.
- Glasserella parasuis was identified in only 1 case in Q1.
Ontario Slaughter Statistics
Federal Slaughter Statistic Summary (Q1 Aggregate)
Dr. Christine Pelland reported the following:
- Erysipelas carcass condemnations constituted 7.4 % of all carcass condemnations. Absolute numbers of erysipelas condemnations / 100,000 inspected declined in comparison to Q4 2023 but were greater than Q1 2022. The seasonal pattern of increased carcass condemnations due to erysipelas in Q4 and Q1 is continuing.
- Peritonitis carcass condemnations had been increasing but there has been a reduction in absolute terms in Q1 2023. This is good news.
Provincial Slaughter Statistic Summary
- The provincial condemnation data shows no significant changes in the causes of partial or whole carcass condemnations in Q1.
CanSpotASF Surveillance Update
There were 24 ASF tests in Q1 2023 as part of the CanSpotASF testing out of 59 cases that were eligible for testing. The main reason that eligible cases can’t be tested in the Canspot ASF program is because fresh spleen tissue has not been included in the sample submissions. Even when it appears that there are no gross visible lesions that are suggestive of ASF it is possible that microscopic lesions suggestive of ASF may be detected on histopathology making the case eligible for CanSpotASF testing. It is, therefore, beneficial for spleen to be included in as many laboratory submissions as possible when field post mortems are carried out. Remember to “Make Spleen Routine!” so that our early detection program has a chance to limit the spread of ASF. More information is available on the OAHN website.
International Disease Topics Of Interest Summary
Dr. Al Scorgie reported interesting international and domestic disease topics.
Porcine Reproduction and Respiratory Syndrome (PRRS)
In March of 2023, PRRSV Lineage L1C (1-4-4) was found in Missouri (71 cases), Iowa (36), Minnesota (20), Pennsylvania (3), Indiana (2), Oklahoma (2) and Nebraska (1). The PRRSV L1C was first identified in Iowa and southern Minnesota. Possible causes of dissemination of this strain of PRRSV are the movement of cull sows and transport trailers returning from processing plants. With the movement of the PRRSV L1C east there is concern that this strain will enter North Carolina. (Swine Disease Reporting System April 04th 2023)
Porcine Delta Coronavirus (PDCoV)
The number of cases of Porcine Delta Coronavirus, PDCoV, has increased in 2023 over 2022. PDCoV cases were increased in 2018, 2021 and 2023. Researchers are unsure why this two-year cycle exists. Cold weather increases viral persistence and makes washing and disinfecting trailers more difficult but that cannot explain why PDCoV would follow a 2-year cycle. (Swine Disease Reporting System April 04th 2023)
Investigation Into Water Line Biofilm and The Possible Impact on Swine Health
Iowa State University studied biofilm in water lines. 3-inch sections of water lines from a swine operation in Iowa were submitted to the diagnostic lab. The diagnostic lab ran 16SrRNA and metagenomic sequencing on the biofilm. The lab found that 47% of the biofilm was from the Enterobacteriaceae family and antimicrobial resistance genes for multiple drug classes were found. From the findings the lab made several recommendations:
- Do not consider groundwater a protected source.
- Consider testing the water annually for water quality, trace minerals and coliforms.
- Flush dead end water lines frequently to remove debris.
- Try to prepare fresh medicated stock solutions daily, discard any residual medicated water after 48 hrs. Cover stock solutions.
- Flush water medicators after use with water.
Further work on biofilm composition, water line disinfection and possible transmission of swine pathogens through groundwater is being done. (Swine Disease Reporting System February 06th 2023)
Prevalence Of Rotavirus in Suckling Pigs in Canada
A study of the prevalence and distribution of porcine rotavirus (RV) group and type in suckling piglets in Canada between July 2019 and June 2022 was done by Carol Malgarin, Francisco de Grau, Sylvain Drapeau and Sebo Channing (Merck Animal Health). RV A, B and C types were the most common pathogenic types identified. Recently, sequencing of the viral protein 7 has become available to further type the strains into G sub-types. An earlier study by Buchan et al in Ontario had found that 69% of diarrhea caused by rotavirus was RV A, 37% were RV C and 13% RV B.
800 samples of rotavirus from across the country were submitted to the Animal Health Laboratory at the University of Guelph for RV type identification and structural protein VP7 sequencing. Out of 346 cases RV VP7 was sequenced. RV C was present in 45.3% of the cases, RV A in 43.2% and RV B in 11.5%. RV C G6 was found in 154 samples, RV A G9 in 112 samples. In 75% of the cases only one strain of RV was identified and the remaining 25% of the cases had more than one strain. Eighteen subtypes were identified through sequencing: 5 RV A, 9 RV B and 4 RV C. Some RV B subtypes were specific to certain regions such as RV B G8 in SK and RV B G25 in MB. RV C G6 was the most prevalent sub-type in all provinces except ON
(Carol Malgarin et al, Leman Conference 2023)
Missouri Gene Therapy Bill Voted Down
The Missouri House Committee on Emerging Issues voted 10-4 against bill HB1169. This bill had several requirements including a label on beef or pork that listed all the vaccines the cattle or pigs had received in their life as well as indicating whether GMO corn or soyabeans had been fed. The vaccine listing was focused on mRNA vaccines. Part of the bill stated “any product that has been created to act as, or exposed to processes that could result in the product potentially acting as, a gene therapy or that could otherwise possibly impact, alter or introduce genetic material or genetic change into the user of the product…” One of the possible reasons that mRNA vaccines were included in this bill was that there was confusion and misunderstanding about mRNA Covid vaccines. Besides the cost of listing all the vaccines on the beef or pork label there was concern about cattle and pigs moving from state to state. Similar legislation has been introduced in Arizona and Tennessee. (Progressive Farmer 2023/04/210)
How can you Participate in OAHN?
Look for the 2022 Q4 veterinary clinical impression survey that will come out the second of January via an email through the OASV listserv.
The survey takes less than 10 mins time to complete!