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PUBLIC HEALTH REPORTER

apicard@globeandmail.com

I keep reading about a deadly pandemic, but it's not defined. Can you tell us bluntly how bad swine flu could get in Canada?

According to mathematical modelling done as part of the Canadian Pandemic Influenza Plan, a new strain such as swine influenza A/H1N1 could kill 11,000 to 58,000 Canadians in a period of about six to eight weeks. The pandemic could also result in the hospitalization of 35,000 to 138,000 people and leave 4.5 million to 10.6 million others too sick to work, which would have a devastating economic impact.

The range of impact is broad and reflects the fact that it is impossible to predict how virulent a pandemic strain might be. In a typical influenza season, 10 to 25 per cent of people get infected, because many are protected by vaccination and natural immunity. In a pandemic - where essentially no one has immunity - 30 to 50 per cent of the population would likely become ill in a short time period. But it is impossible to know the "attack rate." While these numbers can be frightening, they need to be kept in context. In a typical year, 4,000 to 8,000 Canadians die of the flu and 20,000 to 40,000 are hospitalized.

If there is a swine flu pandemic, will it start immediately?

Outbreaks and epidemics of influenza tend to happen in the winter months. While there are some swine flu cases in Canada now - 34 cases as of last night - epidemiologists think it likely that the disease will disappear in Canada in the coming weeks, with the advent of warmer weather; but they also fear it could return with a vengeance in the fall. History tells us pandemics don't hit in one fell swoop, but in waves.

Why is the mainstream media covering up the truth about the swine flu epidemic? It's obvious that the real reason for the epidemic is factory farming. Massive hog operations are incubators for disease and they are the source of this virus.

Much has been made of the fact that Edgar Hernandez, the five-year-old boy dubbed "patient zero," lived near a big hog farm operated by U.S. company Smithfield Foods. But the fact remains the source of the new virus is not yet known - it could be a big farm, a small farm, or from a single pig in someone's backyard. Remember, too, that little Edgar had the first laboratory confirmed case of A/H1N1 influenza; it's highly unlikely he was the first person infected. And, unlike bird flu, the source is not particularly important as people are not contracting the illness from swine, but from other people.

That being said, it is worth addressing the broader issue raised - the impact of large-scale commercial farming on human health. David Waltner-Toews, author of Food, Sex and Salmonella, notes that "factory farming" is a largely meaningless term. There are well-run, large-scale operations with highly educated farmers; crowded, dirty farms where farm workers and animals alike are exploited; and everything in between, so the risk of disease spreading in animals and humans from these sites varies widely. And he adds this sobering note: "I would be the first to say that economies of scale are the economies of epidemics (large populations of susceptible animals mean that if disease gets in it will spread more easily). However, farmers are giving us what we want - low-cost meats in large quantities - in the best way they know how." In other words, we are reaping what we sow, and disease may be a part of the harvest.

Is there any evidence yet in H1N1 swine flu victims of a cytokine storm?

The job of cytokines is to send a signal to immune cells like T-cells and macrophages that there is an invader in the body such as a swine flu virus. They also tell the immune system to produce more cytokines. Normally, this feedback loop is self-limiting but in some instances production goes into overdrive - a cytokine storm. The overstimulation of the immune system can cause a dangerously high fever and damage internal organs, the lungs in particular. It is believed that during the 1918 Spanish flu epidemic, the death rate was extremely high because the virus somehow triggered a cytokine storm.

But, to address the question, no, there is no evidence of a cytokine storm in people who contracted swine flu. Their symptoms are similar to seasonal influenza - sudden high fever, cough, and breathing problems in severe cases.