Animal viruses can be more deadly than their human
counterparts

A lot of people have been commenting about the apparent overreaction of governments to the swine flu.  Why go to such extreme measures to deal with simple influenza?  The reason has to do with the flu pandemic of 1918-1919.

Over those two years, at least three waves of flu struck killing over 600,000 people in the U.S. and a staggering 30-50 million people worldwide.  People died at such a high rate that cities ran out of caskets and dead bodies were stacked on porches and in the streets.

Governments have been concerned that history might repeat itself because the two flues share one thing in common–they both started out as animal viruses.  And our bodies are not particularly good at fighting off viruses new to humans.

Each year a new flock of flu strains kicks off the flu season.  Almost always these strains are variations of human flues from previous years.  What this means is that we have seen cousins of these viruses in the past and so have a leg up on mounting an attack and defeating them.

We do not have this same leg up on animal viruses.  Our immune systems haven’t seen anything like them and so can’t mount a quick attack.  The end result is that the percentage of people who die from animal flues tends to be much higher than from run of the mill human flues.

In any flu season, the CDC estimates that 5-20% of the U.S. population ends up with the flu.  And that 36,000 of these people die.  The numbers of deaths would be much higher if a truly deadly animal flu virus like the bird flu from a few years back were to emerge and gain the ability to spread from person to person.  (The bird flu was never more than a few isolated cases since it never gained this ability.)

At first blush, this is what the swine flu looked like.  The disease spread easily among people and, in Mexico at least, appeared to be more deadly than normal flues.  So governments around the world sprang into action.  Since flu is spread through contact, governments tried to keep people away from each other.

They closed schools at the fist sign of trouble.  Mexico closed restaurants, theaters and museums too.  All of this was done in an attempt to prevent the spread of a disease like the flu of 1918.

At least outside of Mexico, this flu does not seem to be too much worse than other flues.  So it may be that governments overreacted this time.  But I would prefer that they overreact like this as opposed to ignoring a deadly pandemic.  We don’t want another 1918 on our hands.

More info on The 1918 Flu in San Francisco

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Fearing 1918 11 May,2009Dr. Barry Starr

Author

Dr. Barry Starr

Dr. Barry Starr (@geneticsboy) is a Geneticist-in-Residence at The Tech Museum of Innovation in San Jose, CA and runs their Stanford at The Tech program. The program is part of an ongoing collaboration between the Stanford Department of Genetics and The Tech Museum of Innovation. Together these two partners created the Genetics: Technology with a Twist exhibition.

You can also see additional posts by Barry at KQED Science, and read his previous contributions to QUEST, a project dedicated to exploring the Science of Sustainability.

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