Ontario Animal Health Network (OAHN) Swine Network Quarterly Producer/Industry Report

Ontario Porcine Reproductive and Respiratory Syndrome (PRRS) Update

PRRS was rated as common or very common by 90% of practitioners, and >40% of respondents  indicated that PRRS activity was increasing in Q4. Veterinarians commented that they were continuing to deal with cases that were clinically more severe. Individual outbreaks continue to range from mild clinical signs to extremely severe.

Dr. Christine Pelland reported that Ontario has been challenged with frequent PRRS virus outbreaks.  These outbreaks are occurring all year long and occur even during the summer months.  The strains encountered have been tough.  The 1-8-4  and 1-4-2 “genotypical families” of PRRS viruses have been extremely challenging with devastating effects seen in the sow barn with increased abortions and pre-weaning mortality.

Porcine Reproductive and Respiratory Syndrome (PRRS) 1-4-4 in the U.S.A.

Dr. Al Scorgie provided a summary of a recent webinar sponsored by Swine Health Information Center (SHIC).  Multiple speakers including practitioners, pathologists, virologists and epidemiologists discussed the new variant of PRRS 1-4-4 in the U.S.A.:

• PRRS 1-4-4 is not a new strain and has been isolated as far back as 2006. In September and October of 2020, labs in Minnesota and Iowa started seeing an increase in PRRS 1-4-4 isolates. Sequencing showed that this was a unique genetic cluster of PRRS 1-4-4 indicating that the PRRS 1-4-4 had mutated.
• Dr. Paul Yeske from the Swine Vet Center in Minnesota, U.S.A. commented that infected herds were seeing severe clinical signs with PRRS 1-4-4 including high mortality in sows, piglets, nursery and finishing pigs. Associated abortions, increased mummies and stillbirths and severe losses for 2 to 4 weeks have been reported. This strain of PRRS virus spreads quickly. An example given was there would be 5 sows off feed one day and 200 sows off feed the next day.  The severity of the PRRS break did not appear to be different whether the herd was naïve, vaccinated or had undergone a PRRS break in the last year.  The same was true for finishing pigs and even vaccinated finishing pigs had high mortality and average daily gain (ADG) could drop from 1.0 kg/day to 50 g/day.  Mortality in some nurseries was as high as 50%.

Take Home Message:  Ontario does not want this virus to be detected here.  Heightened biosecurity is essential!

Strep. zoo-*First detection of this pathogen in an Ontario swine herd*

In Dec 2020, Ontario detected for the first time Streptococcus equi zooepidemicus ( Strep. zoo) as the causative bacterial for a sow mortality case workup. This bacteria was isolated from a case that clinically presented with mild illness in sows along with an increase in sow mortality. This case was submitted to Animal Health Lab (AHL) in Guelph. Strep. zoo is known to cause infections in several species (commonly in equine).

Strep. zoo was identified in a sow operation in Manitoba in 2019. In that case they saw extreme sow death loss with up to 40% sow and gilt mortality.  At the same time the Manitoba sow herd was affected, the United States Department of Agriculture (USDA) reported that a sow processing plant in Tennessee had experienced an outbreak of 40% sow mortalities in holding pens. Subsequently it was learned that there was a connection between the infected Canadian herd (in Manitoba) and the processing plant.

The source of the Ontario sow herd infection is still unknown. There were no known connections between the Manitoba sow herd and the Ontario herd.

Take Home Message:  Producers should immediately notify their veterinarian if they see sudden deaths in breeding stock, lethargy, fever and decreased appetites. In order to avoid border disruptions, it is important that if you are seeing clinical signs consistent with a Strep. zoo outbreak that you do not to ship cull-sows.

There is a heightened alert with this pathogen and there is a lot of concern in Western Canada about it. It is also appropriate to note that Strep. zoo does have the potential to infect humans. In all the cases mentioned in this report there has been no evidence of human infection. Appropriate precautions should be taken in order to prevent transmission to humans including good hand hygiene and wearing a mask when dealing closely with sick animals.

Sequencing of the Ontario Strep. zoo isolate has revealed that this strain is similar too one that originated in China in 1976 and was similar to the isolates that cause the most recent outbreaks of septicemia in pigs in Manitoba, Pennsylvania, Ohio and Tennessee.

Porcine Circovirus Type 2 (PCV2)

PCV2 was rated as being rare by 70% of practitioners.  Of the veterinary respondents, 30% commented that PCV2 frequency had increased in Q4. Cases seen were associated with sow herd instability in immunity or with associated growing pigs that were not vaccinated.  Take Home Message:  PCV2 vaccines are very effective at controlling this disease.  If you are seeing clinical signs of wasting pigs that could be associated with Circovirus please consult with your veterinarian to determine a vaccine protocol along with the correct timing of vaccination that will work in your herd.

African Swine Fever (ASF) Vaccine Update

United States Department of Agriculture (USDA) Continues to work on a Promising ASF Vaccine (Source:  Feed Strategy 01/29/21)

Dr. Al Scorgie summarized some U.S.A. ASF vaccine research that we felt swine producers may be interested in:

• Chavande Jacobs-Young from the USDA said that research continues on a new live virus vaccine that has been rated as highly effective for ASF. The vaccine is being developed through a public-private partnership and has been licensed to commercial partners so that they can continue to research and ultimately develop the new vaccine.  The vaccine was developed by deleting an identified gene known as the I177L gene.
• Vietnam is planning to produce an ASF vaccine later in 2021. The vaccine was developed from a prototype supplied by the USDA.
• The Philippines is reporting that a rapid test kit for ASF had been produced by Central Luzon State University. This rapid test kit can analyze tissues, blood or saliva and surfaces with results available in 1 hr.

New Strains of ASF in China (Source:  Reuters 1/28/21, SHIC 1/27/21, Promed 1/22/21)

Dr. Al Scorgie summarized some media reports that we felt swine producers may be interested in:

• Reuters is reporting that two new strains of ASF have been identified in pigs in China. The strains are missing one or two key genes present in wild ASF viruses. One theory is that these new gene deleted strains originated from an unregulated live virus ASF vaccine (most likely by producers making their own vaccines from live virus on their farms).
• In August, the Chinese government said it would test pigs for different strains of the virus as part of an investigation into illegal vaccine use. China’s Harbin Veterinary Research Institute is working on an ASF vaccine with the same genes deleted. The sequence of these new strains has not been shared.  There is little information on what happens to pigs that are infected with these new strains.

CanSpot ASF Surveillance Update

ASF surveillance continues through the CanSpot ASF pilot project at the Animal Health Lab (AHL).  Samples submitted to the lab that meet case eligibility could be included in this pilot project with veterinary consent.  To date Ontario has tested 8 cases since August 2020 through the CanSpot ASF pilot and all testing has been negative.  This number is significantly lower than expected and puts Ontario way below the other provinces with Quebec having tested 23 cases to date and the western provinces testing 36 cases in Q4 alone.  One roadblock encountered has been inappropriate tissues in order to perform this testing.  When submitting tissues to the lab, even for respiratory cases, please also include spleen.

This pilot project is a positive step in granting provincial labs the ability to perform ASF testing in low-risk cases.  This laboratory capacity will be essential when ASF is detected in Canada. 

It is very important that veterinarians and producers support this initiative.

How can producers engage in OAHN?

• Read our quarterly producer reports and let us know what you think!
• Discuss the material included in these reports with you herd veterinarian and other swine producers. Help us spread the word!

What to do if you see feral pigs in Ontario…

• OMAFRA is working with the Ministry of Natural Resources & Forestry (MNRF) to put together a wild swine strategy for Ontario. The first step will be to try to identify wild swine within Ontario.
• The MNRF has set up a page on iNaturalist at: www.inaturalist. org/projects/ontariowild-pig-reporting for residents to document any possible wild pigs in Ontario. Sighting information can also be emailed to MNRFSpeciesConservationPolicyBranch@ontario.ca.