By Philip Ling and Tiffany Crawford, With files from Reuters, Linda Nguyen and Sharon KirkeyMay 3, 2009 3:02 PM
Health officials have found the H1N1 flu virus in a swine herd in Alberta.
Health officials have found the H1N1 flu virus in a swine herd in Alberta.
Photograph by: Larry Wong, Edmonton Journal
HONG KONG — The World Health Organization cautioned people on Sunday to avoid unnecessary contact with animals sick with the A H1N1 virus, while an infectious disease expert in Hong Kong warned the risk of a swine flu pandemic has dramatically increased, after more than 200 pigs on a central Alberta hog farm were found infected with human swine flu on the weekend.
It's believed the Alberta case is first time anywhere in the world the new H1N1 influenza A virus has been found in pigs.
The discovery had experts weighing in Sunday on what, if any, measures should be taken now that the virus has spread to animal herds. Some countries, including China, banned Canadian pork products, despite calls from the industry that the meat is safe.
On Sunday, a WHO official agreed the consumption of pork is safe and said there are no plans to put down any of the infected animals.
"At present there is no recommendation for culling," said Dr. Peter Ben Embarek, adding WHO officials will look into whether more control measures are needed to protect human health. As of Sunday morning, the number of cases worldwide had climbed to 786.
Canadian officials said consumers should not be concerned about the virus entering the food chain.
"We have determined that the virus, H1N1 influenza A, found in these pigs, is the virus which is being tracked in the human population," Dr. Brian Evans, executive vice-president of the Canadian Food Inspection Agency and Canada's chief veterinary officer, told reporters.
"The chance that these pigs could transfer the virus to a person is remote. Nevertheless, we are following an appropriately measured approach," Evans said, stressing there is "no food-safety concern related to this finding. Consumption of pork is not considered a route of transmission to humans."
Although he says the food is safe, Dr. Ho Pak-leung, associate professor at University of Hong Kong's microbiology department, is concerned the transmission of the flu virus from humans to pigs indicates a new medium of transmission for the virus.
Ho says he believes this H1N1 flu virus will become increasingly difficult to control if more pigs are infected by this human swine flu virus. There's also a high risk the virus can mutate inside infected pigs, creating new strains of the animal flu, he said.
The transfer of a flu virus from humans to pigs is not unheard of, he says, pointing out the influenza viruses of the Hong Kong flu pandemic also transferred from humans to pigs, and vice versa. That pandemic killed nearly one million people in 1968 and 1969.
"Once the human virus is transmitted to pigs, anyone that comes in contact with infected pigs will have chance of contracting this (H1N1) virus," he says.
There's also a high risk the virus can mutate inside infected pigs, Ho adds, creating new strains of the animal flu.
"A single pig can be infected with different influenza viruses," he says. "So, there's a chance that the genes of the influenza virus may 'shuffle' inside the pigs . . . forming a new virus."
However, Ho stresses that pork products are safe to eat, since the H1N1 disease cannot be contracted from eating cooked pork, as the flu virus is killed at temperatures of 70 C.
So far, China, the Philippines, El Salvador, Honduras and Ukraine have stopped accepting Canadian pork since the H1N1 cases were identified in Canada, while South Korea is not accepting live hogs.
"The pigs or relevant products sent to China after the declaration would be destroyed and those sent to China before Saturday would have to pass A H1N1 tests," China's Xinhua News Agency said, citing a China agriculture ministry announcement.
Agriculture Minister Gerry Ritz urged Canada's trading partners to make decisions based on "sound science," not emotion. On Wednesday, Egypt ordered a nationwide pig slaughter as a precaution against swine flu.
Ritz said he spoke to U.S. Agriculture Secretary Tom Vilsack to make him aware of the situation. "He has assured me that Canadian hog producers will continue to have access to the American market," Ritz said in a statement. "We will continue to work with our American partners as we deal with this issue."
Federal officials believe the infected pigs contracted the virus from a Canadian worker who returned from Mexico on April 12 and arrived on the farm two days later, showing flu symptoms shortly thereafter. One other person on the farm has had mild symptoms. Officials are awaiting test results.
Both the worker and the approximately 220 infected pigs are recovering, but the animals have been quarantined, Evans said.
Meanwhile, 34 new human cases of swine flu were confirmed Saturday, bringing the total number of confirmed cases in Canada to 85.
"We continue to see mild cases and full recovery in Canada, but our vigilance and efforts need to continue, and our heightened surveillance will lead to more and more confirmed cases," Dr. David Butler-Jones, Canada's Chief Public Health Officer, said. He said the risk to most Canadians remains low.
Most of the new cases come from Nova Scotia, where 17 were reported. Seven more were from B.C., another seven were from Alberta, plus two in Ontario, and one in Quebec.
In the U.S., a health official with the Centers for Disease Control told a news conference Sunday doctors believe the virus is widespread among young people but that "most of those people are recovering."
"I don't think we're out of the woods yet," said Dr. Anne Schuchat. "I do expect more deaths and I am particularly concerned about what is going to happen in the fall."
The CDC has reported 226 cases of the new H1N1 swine flu virus and one death in 30 states.
Nova Scotia's chief public health officer said that, of the province's 17 new cases reported Saturday, six have no connection with a private boarding school that recently sent a music class to Mexico. In all cases in the province prior to Saturday, all had a link to King's-Edgehill School in Windsor, N.S.
Dr. Robert Strang said provincial health officials have been on alert for the swine flu to spread outside of the school. All the patients are experiencing mild symptoms.
Quebec revealed Saturday it has a second case, a child whose family returned last week from a vacation in Mexico, the country where the outbreak began.
On Sunday, Mexican Health Minister Jose Angel Cordova said the country's H1N1 flu virus epidemic had passed its peak and was now declining.
"The evolution of the epidemic is now in its phase of descent," Cordova told a news conference, adding that the outbreak appeared to have peaked in Mexico between April 23 and 28.
The WHO says it has not seen a sustained spread of the swine flu virus outside North America, but that a pandemic was still "imminent."
Health officials continue to remind the public that the seasonal flu is also responsible for making thousands of people sick and for killing an average of 4,000 Canadians every year. Normally, fewer than 0.1 per cent of people with influenza die, if they have no underlying medical conditions.
Source: http://www.canada.com/Health/Experts+urge+caution+after+found+Canadian+swine/1559511/story.html 
