A recent report recommends that workers on hog farms be monitored for swine flu to prevent a possible pandemic.
The report, which appeared in the December issue of the journal Emerging Infectious Diseases, follows a case in 2006 in which a seven-month-old child on an Alberta communal farm was diagnosed with swine flu.
It’s the first confirmed case of swine flu in a human in Canada. Later tests confirmed more than half of the people on the 90-member communal farm tested positive for the flu strain, said Dr. Joan Robinson, a pediatric infectious disease physician at the Stollery Children’s Hospital in Edmonton.
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“The biggest concern is that eventually it could mutate so there could be genetic changes in a strain of swine flu that would allow it to be easily spread from person to person,” said Robinson, co-author of the report.
“Then the other big concern is it could maybe interact with a human strain. If someone had human influenza the same time they got swine influenza, the two viruses could join together and could end up with a virus that was part human, part swine that was very rapidly spread from person to person.”
Pandemics can result when major changes occur in the strain of influenza that is circulating.
In 1918, an avian strain joined with a human strain that was spread easily from person to person. More than 20 million people worldwide died. Two subsequent pandemics – the 1957 Asian flu and the 1968 Hong Kong flu – were not as dramatic because they were changes from human strains.
It is not unusual for hogs to have different strains of influenza. Robinson believes there is an existing low-level infection of swine flu among swine workers, but it often goes unnoticed because symptoms of fever, cough and aching muscles are the same as other flu symptoms.
“Fortunately, this strain that swine usually get does not cause significant symptoms in humans and they’re usually not spread easily from person to person,” she said.
Robinson advocates using some of the pandemic research funding to report hog workers who have flu symptoms that are more severe than usual.
“If you had dramatic cases among swine workers, you’d have to look harder at quarantining people, coming up with a vaccine or all those measures.”
However, she said only severe cases should be reported, not every symptom of flu.
A more detailed strategy is needed for preventing a possible pandemic she added. Planning is now done at the federal, provincial and regional levels.
“I think we need a plan from higher up. When people have influenza-like symptoms, at least half the time they don’t have influenza – they have some other virus,” Robinson said.
“The other problem is the average doctor in small town Saskatchewan might not even be aware how to test for influenza.”
While it’s not known how the Alberta child contracted the virus, investigators believe the swine flu originated in a group of pigs shipped from Manitoba to the farm.
“The theory is one of the adults in the household was in contact with the pig, came home and either didn’t wash their hands before they touched the baby or it was on their dirty clothes and the wife picked up their dirty clothes and then touched the baby,” she said.
“I think it was probably spread indirectly. The parents were really quite insistent that the child had not been inside the barn.”
She said that particular case of swine flu was probably discovered only because the child was brought to the hospital with flu symptoms in September, which isn’t a normal time to see flu cases. A virus sample was later sent to the national laboratory in Winnipeg.
Robinson said the swine flu case was not made public immediately because the child had recovered by the time doctors identified the swine flu strain. While other members of the farm tested positive for swine flu, none were hospitalized.
