Via The Toronto Star, Helen Branswell of The Canadian Press writes a very useful article: H5N1 and H1N1: Bird flu? Seasonal flu? Get your flu facts straight. Excerpt:
Canada has reported the first case in North America of an infection with the H5N1 avian flu virus.
A woman from Alberta who had travelled to Beijing, China, in December fell ill and died after her return.
With H1N1 — seasonal flu — making headlines these days, this new development may trigger flu confusion. So here are some essential flu facts:
What is H5N1? It’s the original “bird flu.” This is the virus that burst out in Asia in late 2003 and early 2004. Millions of poultry died or were culled as the virus — which is highly infectious among birds — spread in Vietnam, Thailand and other countries. It hasn’t been making as many headlines lately, but it’s still causing bird outbreaks and occasional human cases in parts of Asia.
Highly infectious among birds? What about people? Since late 2003, just under 650 people from 15 — now 16 — countries are known to have contracted this strain of flu. But it rarely infects humans. Untold numbers of people in affected countries would have been exposed to it over the years but very few have gotten sick. And while there have been a few cases where one sick person spread it to others, those chains of transmission have always died out. Unlike human flu viruses, this virus is not an effective person-to-person spreader.
Is it likely the Edmonton case will lead to more infections? Health authorities say there are no signs of illness among the woman’s contacts or the health-care workers who cared for her. They’ll need to watch those people for a couple of weeks to make sure. But this could be a one-off case.
So what’s the fuss about? The virus doesn’t spread person to person now. But science can’t tell if it will evolve and acquire the capacity to spread human to human. So flu experts and the World Health Organization watch this virus closely. Also, about 60 per cent of people who have been known to have been infected have died. So while infections are rare, they’re often severe.