Variant 1-1-4 Lineage 1C has caused trouble in the Midwestern U.S.
By Jackie Clark
Swine health experts in the U.S. have been working to address a particularly pathogenic strain of porcine reproductive and respiratory syndrome (PRRS). Canadian producers have not identified the variant, 1-1-4, Lineage 1C, in Canada yet. The increased pathogenicity of this viral variant means it has a greater ability to cause disease in the host.
“We’ve had an active spring for PRRS, but definitely haven’t seen this 1-4-4 1C variant,” Dr. Egan Brockhoff, veterinary counselor for the Canadian Pork Council, told Farms.com.
The variant “has been primarily identified in Iowa and Minnesota,” he explained. About “98 per cent of their current cases … are in those two states. The virus is moving a little bit but is still largely isolated to those two states. They’ve had two waves of the virus so far. One in the fall and one again in this spring.”
It is unlikely that the variant would spread to the Canadian herd through live pigs, because we don’t tend to move market hogs or cull sows north to Canada from the U.S., he added.
“The vast majority of our pig flow is from north to south. We ship isoweans, feeder pigs, finisher pigs, cull sows, and genetic material to the U.S.,” Brockhoff said.
“Occasionally we purchase genetic material to come north, but it would be really normal for the industry to be very aggressive with PRRS surveillance with any genetic material coming north.”
However, transport trucks present a potential vector, and transport biosecurity vigilance should remain a priority for the industry.
“That particular virus coming north would mean a breakdown of transport biosecurity, maybe of people biosecurity, as we start going to more conferences around the world again,” Brockhoff explained.
Though this particular variant isn’t in the Canadian herd, PRRS is still an active, endemic, economically significant virus in Canada, he said. “We tend to have higher levels of incidence in Ontario and Quebec, lower levels in Manitoba, and then pretty low levels in Alberta and Saskatchewan, and it’s directly related to swine movement and hog density.”
As pig density decreases, so does the prevalence of the virus.
“PRRS is an RNA virus and it’s changing all the time,” he explained. “Every once in a while we see new strains emerge that give us some grief, but it’s a virus we’re constantly doing work on. Every year in Canada there is significant effort put into prevention, control and eradication of PRRS.”
PRRS is “one of those viruses where there’s always a new strain to think about.
There’s no question that this 1-4-4 Lineage 1C strain that’s been identified in 2020 caused a lot of trouble” in the U.S.
However, currently, the variant is not present in the Canadian herd.
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