I find the whole subject of influenza mutations and the idea of pandemics to be frightening, yet fascinating. The buzz has been getting louder in the last couple of years, but I really started noticing it in 1997 during the Hong Kong outbreak of avian flu.

Before then it was thought that bird flu viruses couldn't jump to humans.

Now the WHO and the CDC are watching the progress of avian flu in pigs. The fear is that, since pigs can share viruses easily with both birds and humans, a mutation will occur within a population of pigs that will create a virus that is just human-like enough to spread easily, but bird-like enough that we have no immunity to it.

The 1918 Influenza Pandemic is now thought to have been caused by a bird flu. With the final death toll at over 20 million, it was nothing to sneeze at. (ha!) The virus was particularly lethal, and was transferred very quickly from person to person and place to place. Check out this map to see the spread in the US over the course of 3 weeks. For a "grippe-ing" account of the devastation, especially if you're not well-versed in biology or epidemiology, I recommend Gina Kolata's Flu. She explains everything in a way that a layman can understand it, without it have a dumbed down feel ala Influenza for Dummies.

So, now you know what kinds of things I lay awake at night and think about. Or, I would, if I didn't have four kids and fall asleep the minute my head hit the pillow...