December 6, 2011
US is keeping a close watch on a strain of influenza originating from pigs but no significant infection among humans, officials say.
The US' Centres for Disease Control and Prevention has prepared a vaccine for the H3N2 of influenza, a strain of pig flu that has recently jumped to humans. The centres have logged 10 infections of the strain in the last three months and five more in three states during the last flu season. And while it has caused no major alarm, health experts are watching it and other strains closely.
"We need to keep a close eye on influenza," said Dr Dick Zoutman, a microbiologist and infectious disease expert. He started work Thursday as Quinte Health Care's chief of staff. He and others have warned against underestimating the flu.
"It's an incredibly clever virus and it can create a new strain that we're not immune to and cause a problem," Zoutman said. He added, "We have to have a high respect for what influenza can do. It's a fascinating creature when you think of it."
Zoutman said it's already known that viruses can move from birds and pigs to people, but the circumstances aren't always the same. "Changing weather patterns and changing migration patterns do play a part in these things."
This year's flu shot includes the human variant of H3N2, but "it probably wouldn't do much for this (swine) strain," Zoutman said.
"Occasionally a swine-origin strain will make the leap directly to a human and that's a different infection."
At present, he said, the swine H3N2 is of little concern even to pig farmers because it doesn't cause serious illness in the animals. He said the swine strain would be of greater concern if it was causing widespread human infection. But for now, he said, it remains "exceedingly rare."
Wayne Tucker, director of communicable disease control for the Hastings and Prince Edward Counties Health Unit, monitors reports about flu and other diseases.
So far, he said, "I haven't seen anything of any concern" about the swine-origin H3N2. Tucker said there are "no concerns locally" about it.
Health unit nurses have given 6,115 flu shots this year, up from about 5,000 in 2010. But since the vaccine is also given by doctors and other practitioners, he said, broader statistics on immunization are tough to compile.
Tucker said it's still early in the flu season but so far "there's no activity locally and no outbreaks." At this time last year, he said, there had been about a dozen local flu outbreaks. "Flu activity across Ontario is extremely low," he said. "Only four cases have been reported.
"That doesn't necessarily mean it's going to be a mild flu season."
Zoutman said the usual basic steps taken during flu season help keep people safe and the more people do them, the safer humans will be. "Clean your hands. Get your flu shot. Watch how you cough and sneeze," said Zoutman. Medical authorities recommend coughing and sneezing into your elbow, not your hand, to limit the spread of germs.
In an October interview, Dr Richard Schabas, the health unit's medical officer of health, recommended getting the flu shot for more than just personal reasons. "In getting the flu shot you're not only protecting yourself, you're also reducing the risk that you will spread the disease to someone who's really vulnerable to the serious adverse consequences," he said.
"If we could get a significant majority of the community vaccinated that would slow the capacity of this influenza virus to spread," Zoutman said. If everyone's immune, he said, "It has nowhere to go." As for H3N2, he said, "we have better early-warning systems so we just have to stay tuned and see what it's doing."