Winnipeg scientists have confirmed a new strain of human swine flu virus is behind an outbreak of severe respiratory illness in Mexico, raising fears that the disease could unleash the next global pandemic.
Mexican authorities approached the Winnipeg-based National Microbiology Lab on April 17 for help in determining the cause of recent outbreaks of severe respiratory illnesses that have killed at least a dozen people and infected more than 900 in south and central Mexico. More than 50 samples were sent to Winnipeg's lab and scientists worked around the clock to determine the cause of the mysterious illness.
Dr. Frank Plummer, scientific director of the lab, said scientists discovered the illness is caused by an H1N1 human swine virus — a brand-new virus against which no existing vaccine will likely protect. The Mexican virus is similar to the viruses responsible for recent cases that have cropped up in California and Texas, suggesting the disease can spread from person to person.
Canada has stockpiled millions of doses of antiviral drugs Relenza and Tamiflu to guard against pandemic flu, but Plummer doubts these drugs will offer much defence against the new strain of human swine flu. Plummer said the virus is a mix of North American swine flu and a swine flu that originated in Thailand, and scientists have no idea where it came from, when it surfaced, or how.
"The viruses are so different we think it's unlikely (existing vaccines) would provide much protection. So if we need a vaccine, which we probably do, we'll have to make one," Plummer said, noting it would take at least six months to make a new vaccine.
"We've had influenza pandemics throughout history and scientists have predicted for a long time that we're overdue for one."
There have been no confirmed Canadian cases of human swine flu, but Plummer said scientists are working to diagnose suspected cases. There were fewer than 10 suspected cases of human swine flu in Canada late Friday.
Mexico has confirmed 20 deaths, but 40 other fatalities are being investigated. At least 943 people across the country are sick from the suspected flu.
Canada's chief public health officer, Winnipegger Dr. David Butler-Jones, said no one knows enough about the new virus to speculate how many people infected with human swine flu will become severely ill. He said anyone who returned from Mexico in the last two weeks experiencing fever, cough or muscles aches should see a doctor.
Canadian officials are in close communication with the provinces, U.S. scientists, Mexican officials and the World Health Organization to keep tabs as the situation unfolds.
"We do not know whether this swine influenza virus or some other influenza virus will lead to the next pandemic," Butler-Jones said. "Scientists and public health agencies around the world remain on high alert."
The acting head of the U.S. Centers for Disease Control, Dr. Rich Besser, said the CDC's labs also confirmed seven cases in 14 samples sent from Mexico, and early analysis of the viruses suggested they are very similar to those responsible for the American cases.
U.S. authorities have raised the confirmed count of their own cases to eight, with the discovery of an additional infection in a child living in San Diego, who has since recovered.
Besser said the CDC is hearing from the public that they are concerned, adding: "We are worried as well."
Meanwhile, Manitoba's chief medical officer Dr. Joel Kettner said animal health officials are watching for any signs of increased illness among hogs, since swine flu can be transmitted from pigs to humans.
"So far we have no indication of any increased swine flu," Kettner said. "But we're watching for it."
Manitoba's chief veterinarian, Dr. Wayne Lees, said 7,000 pigs are tested for a variety of illnesses, including flu, every year. Lees said a notice will be sent to veterinarians across the province to alert them to report any unusual respiratory illnesses in pigs.
In the event the swine flu develops into a global pandemic, Kettner said it's too early to say exactly how the province would respond. Medical experts have been generating pandemic plans for several years, but Kettner cautioned the province can't elaborate about the interventions that would be taken, including who would receive medical treatment first, until disease experts learn more about the illness.
The situation could also change rapidly, and prompt a different response in the coming days, he said.
"The details of these plans cannot be etched in stone," Kettner said Friday.
There is no warning against travel to Mexico, and Kettner said Manitobans planning a trip should use common sense and wash their hands to avoid illness.
— With files from The Canadian Press
SWINE influenza, or swine flu, is a respiratory disease caused by the type A influenza virus.
Swine flu outbreaks spark high levels of illness but low death rates in pigs. Most outbreaks occur during the late fall and winter months, according to the U.S. Centers for Disease Control and Prevention (CDC).
Swine flu viruses do not normally travel from pigs to people and those who are infected usually have direct exposure to infected pigs. The latest eight cases in the United States did not involve direct exposure.
As with other influenza viruses, swine flu viruses change constantly and different variations have emerged since they were identified in 1930.
In addition to swine flu, pigs can also be infected by human and avian influenza.
When flu viruses from different species infect pigs they can "swap genes," causing new viruses to emerge.
The CDC typically reports one case of human swine flu every one to two years in the United States but between December 2005 and February 2009, 12 people were reportedly infected with swine flu.
Symptoms of swine flu are similar to the symptoms of seasonal flu and include fever, loss of energy, lack of appetite and coughing. Some people who have contracted the virus report runny nose, sore throat, nausea, vomiting and diarrhea.
Swine flu is not transmitted by food and you cannot catch it by eating pork.
— Canwest News Service