Two human cases of influenza variants normally found in pigs have been detected in Manitoba.
The cases — one of human influenza A(H1N1)v and one of human influenza A(H1N2)v — were found in early April in two unrelated individuals in different southern Manitoba communities, said Dr. Brent Roussin, Manitoba's chief public health officer.
They were detected when the two individuals independently sought testing after developing an influenza-like illness, Roussin said at a Friday morning news conference.
Both people experienced mild symptoms and fully recovered.
There is no risk to the public, Roussin said, as the strains don't transmit easily from human to human.
Both people were tested for COVID-19, but those results were negative. The province has heightened screening for influenza during the pandemic, so the samples were re-evaluated. That's when the strains were identified, Roussin said.
Influenza viruses from pigs do not normally infect humans but they can occur rarely and sporadically, he said.
One of the Manitobans has direct exposure to a swine population, but the other has indirect exposure.
There have only been 29 H1N2 cases globally since 2005. There were none in Canada until last November, when Alberta reported a case.
The H1N1 case is only the second ever reported in Canada. The first was in Ontario in 2012, a news release issued by the Manitoba government said.
For two independent cases to come up around the same time is sheer coincidence, most likely related to the abundance of flu testing being done, Roussin said.
Investigations into the cases are ongoing to determine how transmission may have occurred and to make sure there are no other infection. There is no sign of sustained human-to-human transmission at this time, he said.
"It is certainly possible that this is a true increase in the number of these cases, possibly occurring from exposure to infected pigs or through subsequent, limited human-to-human transmission."
Reporters asked specifically if the person who had indirect exposure to pigs caught the virus from another individual — a possibility that might not be ruled out by a lack of "sustained" transmission.
"We don't have details on that right now," Roussin said, but underscored that there is no risk to anyone.
"We have tested many close contacts and looked at respiratory results from many individuals in the region and have found no other evidence of spread."
About 170 negative COVID-19 tests from people in that region were re-tested for influenza and all were negative, Roussin said.
The two cases are only being made public because that's required under international health regulations, he said.
'Absolutely safe to eat'
Dr. Scott Zaari, Manitoba's chief veterinary officer, emphasized on several occasions during Friday's news conference that people should not be worried about the meat supply.
"Pork is absolutely safe to eat," he said, and the two cases will have no impact on transportation of pork products across borders.
"I do want to be clear that these viruses are not a food-related illness. It's not transmittable to people through pork meat or other products that come from pigs."
There is no epidemiological evidence to link the two cases to any particular swine herd, he said.
"We've got indirect and direct contacts with our human patients, but that's not being found in the swine herd."
Asked for further details about where the cases were found, Roussin and Zaari wouldn't narrow it down beyond the massive region of southern Manitoba.
They also wouldn't provide any information about the setting linked to the cases — whether the pigs were part of a large hog operation or a small farm, or if the direct contact was made through transportation.
They did urge anyone who works with pigs or poultry and has influenza-like symptoms to identify themselves as an agricultural worker to medical officials, including at COVID-19 testing sites, to help identify any potential additional influenza cases.
'We always have to be prepared'
Manitoba Pork, which represents pork producers in the province, reminds hog farmers to follow biosecurity protocols and strengthen them where appropriate. They should also avoid contact with livestock if experiencing flu-like symptoms, a news release says.
Reducing stress on the animals is a key component to preventing illness in them, said Andreas Zinn of Zinn Farms, a livestock farm that handles pigs, chickens, eggs and rabbits.
"When an animal is stressed, it is more likely to be susceptible to illnesses because the immune system is stressed," said Zinn.
Giving animals room to move around and setting them up in relatively sanitary environments can help reduce their stress, he said.
The influenza cases announced Friday are a reminder that COVID-19 is not the only infectious disease circulating in the world, said Jason Kindrachuk, a virologist at the University of Manitoba.
"We certainly need to be appreciative of the fact that yes, we will get through this pandemic, but that doesn't mean this is the last one," said Kindrachuk.
"We always have to be prepared."
The cases also show that the surveillance systems in place to identify emerging influenza variants worked well, he said.
Kindrachuk isn't concerned about these cases igniting a new pandemic, but he says influenza should be on the radar of Manitoba health officials.