New flu virus in Sask. needs to be watched: expert

A new strain of flu virus diagnosed in at least two Saskatchewan hog farm workers will likely disappear with those cases, but public health authorities need to keep a wary eye on it in case it spreads, a leading Canadian infectious disease expert warns.

Health and veterinary officials on Tuesday reported that two hog barn workers had been ill with a new strain of flu and a third was suspected of having contracted the same strain. All three recovered and animals in the barns were healthy, officials said<em>Health
and veterinary officials on Tuesday reported that two hog barn workers
had been ill with a new strain of flu and a third was suspected of
having contracted the same strain. All three recovered and animals in
the barns were healthy, officials said.</em></span></p><p><span =

(CBC)Dr. Frank Plummer, director of the National Microbiology Laboratory in Winnipeg, stressed that the novel virus is not connected to the pandemic strain of H1N1 influenza A virus that has infected thousands of Canadians and been linked to 38 deaths across the country.

Tests showed two workers at a hog farm in eastern Saskatchewan had been infected with the novel virus last month and a third is suspected to have been sickened by the same agent. All three have fully recovered.

The new flu is a genetic cocktail of seasonal human flu and a long-known animal strain, said Plummer, explaining that an influenza virus that's been "circulating in pigs for many, many years picked up some new genes from the human H1N1 seasonal flu, nothing to do with this pandemic virus."

"And it's created this brand new virus that's never been seen before."

Plummer, in Toronto on Wednesday for a meeting of researchers from across Canada to discuss the H1N1 flu pandemic, said no other human cases of the Saskatchewan virus have been reported and "the pigs apparently look pretty well."

"So, we've picked up this novel virus. We have to react very aggressively to it. But from what we know now, I think it's probably going to end with those three cases and everything will be fine," Plummer said.

The new strain was identified after tests on the workers came back positive for both seasonal and swine flu — a finding that Dr. Moira McKinnon, Saskatchewan's chief medical officer of health, called unusual.

When the aberrant test results were sent to the National Microbiology Lab for further analysis, scientists discovered genes from two different flu viruses had combined.

Plummer said it's not known when this "reassortment" — the mixing of genetic material — occurred, but he believes it's likely the workers were infected by the pigs, not the other way around.

Nor does he think that there was human-to-human transmission because all three workers got sick at the same time. All had been in Saskatchewan for about a year and had not left the province.

"So that would be consistent with coming from a common source like one pig," he said.

While Plummer believes the chance of this new flu virus genetically recombining with the pandemic H1N1 strain is "very, very unlikely," he cautions that public health officials need to aggressively keep on top of the virus.

"We need to understand the extent of the problem: Is it just these three people or is it more than that? Is it just this one pig herd or is it more than that?" he said.

Canada finds another new flu strain in farm workers

Lisa Schnirring Staff Writer

Jul 8, 2009 (CIDRAP News) – Public health officials in Canada yesterday announced that they have detected a new influenza strain—one that contains human seasonal flu and a swine flu virus—in two workers on a Saskatchewan hog farm.

The workers had mild illness and have recovered, and authorities are investigating a third suspected case, the Public Health Agency of Canada said in statement yesterday.

Canada's health minister Leona Ablukkaq said federal officials are working with Saskatchewan to learn more about the new virus. "Preliminary results indicate the risk to public health is low and that Canadians who have been vaccinated against the regular, seasonal flu should have some immunity to this new flu strain," she said in the statement.

Dr Greg Douglas, Saskatchewan's chief veterinary officer, told Reuters today that the new virus contains genes from the seasonal human H1N1 flu strain and a triple reassortant H3N2 strain that is common in swine populations.

Initial testing on the pigs indicates they were infected with swine influenza A, common in swine herds, but not the new human strain found in the workers, the Public Health Agency said. Further surveillance will be conducted on Saskatchewan's hog industry workers, and the Canadian Food Inspection Agency is providing the province with guidance on swine herd surveillance.

Saskatchewan's health agency said in a statement yesterday that additional responses include reinforcing biosecurity measures at the affected farm and vaccinating the hog farm's workers.

It added that in most cases, viruses such as the one found in the hog farm workers are not transmitted easily between humans. "To date, there is no evidence that this strain has transmitted between humans," the agency said.

Douglas, the province's chief veterinary officer, said in the statement, "It is important to remember that only healthy hogs go to slaughter and that pork is safe to eat. Influenza is not transmitted by eating pork products."

Canada said it has notified the World Health Organization (WHO) about the new virus, as required under international health regulations.

Dr Carolyn Bridges, associate director of epidemiologic science in the US Center for Disease Control and Prevention's (CDC's) influenza division, told CIDRAP News that the reassortment event in Canada isn't surprising. "We know that humans pass influenza viruses to pigs on a regular basis," she said, adding that the human seasonal H3N2 influenza virus first entered North American swine herds in 1998 and that multiple reassortment events have been detected since then.

"This is just another demonstration of how dynamic these viruses are," Bridges said.

The virus detected in Canadian hog farm workers is not a pandemic flu threat because it contains external human virus proteins—the part the immune system recognizes, she said. "That's what matters most, and the flu vaccine provides good coverage. A large proportion of the population has some preexisting immunity." Sustained transmission of the new virus among humans is unlikely, she added.

However, the events highlight the need for ongoing surveillance in pig populations to monitor for changes, Bridges said.

http://www.cidrap.umn.edu/cidrap/content/influenza/swineflu/news/jul0809newflu.html - http://www.cidrap.umn.edu/cidrap/content/influenza/swineflu/news/jul0809newflu.html

Annie