Friday, July 10, 2009

Swine flu pandemic possible in pigs

Last Updated: Friday, July 10, 2009 10:27 AM ET

Scientists say the H1N1 swine flu virus could spread quickly if introduced into swine farms. (CBC)

German scientists are warning of a pig pandemic after tests suggested the swine flu can pass from humans to hogs and then infect a whole herd.

A team of virologists at Germany's national animal health research lab recently infected five pigs with the human strain of the H1N1 virus and put the sick pigs in a room with three healthy pigs.

Within four days, all the pigs had the flu. All of them recovered.

A research paper to be published Friday in the Journal of General Virology warns "the high transmissibility of the virus observed in humans also applies to pigs." That increasingly puts pigs at risk as the virus spreads among humans.

"It must be assumed that this virus will spread fast and efficiently if introduced into swine farms, possibly establishing endemic infections," the paper says.

"With the increasing numbers of human infections, a spillover of this virus to pigs is becoming more likely."

There is no evidence pigs are passing the swine flu virus to humans, or that eating pork products poses an infection risk.

Dr. Thomas Vahlenkamp, who headed the team of virologists at Germany's Friedrich Loeffler Institute, said the tests show how susceptible pigs are to the virus.

"We would not claim that the virus can easily be transmitted to pigs," he said. "But at least if the pig is infected, it can transmit it quite easily between pigs."

The Canadian Pork Council says fears of a pig pandemic are overblown since the animals are kept away from people.

"It's not like … some of the other animals or livestock that are just out in a field," spokesman Gary Stordy said.

"Since they are in enclosed structures with ventilation, there's very minimal contact with unauthorized [people] or the general public. There's generally very limited access to a farm just because of bio-security measures."

Chickens not affected

This is not the first time researchers have shown pigs can catch the human strain of the H1N1 virus. British scientists ran similar tests in May with the same results. But it's believed the German scientists are the first to publish their findings in a scientific journal.

The Germans also added a twist to their experiment by throwing five chickens into the mix to see if the birds would catch the virus from the sick pigs. But the fowls stayed fit.

Researchers then tried to directly infect the chickens with the virus, to no avail.

"We don't know whether chicken in general cannot catch the infection, but at least in our hands with this isolate from a German patient we could not infect chicken," Vahlenkamp said in an email.

Canada is only one of two places where the pandemic virus has been found in pigs. The other is Argentina.

In April, swine flu appeared in pigs on an Alberta farm. At first, health officials thought a farmhand who had been to Mexico and fell ill upon his return infected the pigs. But blood tests showed the worker didn't infect the herd.

The farmer who owned the pigs later culled his entire herd when he couldn't sell the animals.

Two workers at a Saskatchewan hog farm recently caught a brand new virus, and a third is thought to have been sickened by the same thing. All three have fully recovered.

Health officials say the new virus is not connected to the current swine flu pandemic that has infected thousands of Canadians and been linked to 37 deaths across the country.

The 10,000 to 15,000 hogs on the Saskatchewan farm are all reportedly healthy. That's sure to have drawn a sigh of relief from the farm owner since it's common to see influenza in pigs, and human transmission to pigs is known to occur.

The German scientists say experiments are underway to see whether there are any vaccines available for pigs that might stop the spread of the swine flu.

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