Monday, May 15, 2006

R0 of the bird meme

Lindsay over at one of my favorite blogs, Majikthise, has tagged me with the ten bird meme. Given that bird flu is the major topic here these days you can take this as some kind of sick joke, but I never refuse a meme tag, especially if the tagger is Lindsay. Meme tags are tasks one blogger sets another; you can think of them as some kind of chain letter or, more appropriately, a contagious task that spreads through the blogosphere. Sometimes you have to tag two or three other bloggers. Since Lindsay only tagged me, I am assuming the basic reproductive number, R0, is slightly less than one.

You can read more about R0 at my entry over at The Flu Wiki, but briefly, R0 is the average number of new cases of infection for each infective case introduced into a susceptile population with random contact. In this case, R0 is slightly less than one for two reasons. It would be exactly one if there weren't some small chance that I would try to tag another blogger who has already been tagged, or, more likely, that eventually the tagged one will not know they have been tagged or just decide not to do it.

The importance of R0 in infectious disease epidemiology is that if it is above one, the number of infected people grows and if it is below one it doesn't. So epidemics are characterized by R0's above one. For influenza R0 has been estimated to be somewhere between 1.3 and 3.5 (even those boundaries are approximate), which is much less than some diseases, like mumps or measles where R0 might be above 10. But because the serial interval (the time from one infection to another) is short, flu can spread quickly.

Where was I? Oh, yes, the bird meme. The task set for me by Lindsay was to pick my ten favorite birds. This is a tough job for people who know a lot about birds, and some fifty or more bloggers have already done this. Lindsay got tagged by the inimitable Coturnix, whose Science & Politics blog is one of the best science blogs around. Coturnix (aka Bora) had actual reasons and pictures of the birds he likes. Lindsay had pictures. I am clearly the most efficient because I have neither. In fact, this was a really tough meme for me because I had trouble even naming ten birds. I'm a city boy. I can only stand up on asphalt.

So here are my ten choices, culled (excuse the phrase) from my impoverished urban idea of the bird world:

crow, pigeon, sparrow, starling, robin, chicken, turkey, goose, chickenhawk (you know who you are) and the generic "bird" (used by Boston motorists to greet each other).

I tag Melanie of Just a Bump in the Beltway, my Flu Wiki partner, who says she knows something about birds. We'll see.