There have been all sorts of confusing and contradictory numbers coming out of Mexico over the last few days relating to cases of Swine Flu and deaths attributed to it. What caught our eye was that the Mexican government actually announced that tests have now shown that a substantial number of the deaths (about half of them) originally attributed to Swine Flu were actually caused by different ailments. And only a very few have been confirmed as swine flu cases.

Dealing with statistics in a climate such as this is a tricky business because you don't want to inspire panic or sow complacency. What's more it's important to remember that the number of confirmed or suspected deaths in Mexico is just one variable of many in trying to find out how virulent the virus is. But we've been getting a lot of questions from readers about what these numbers mean and why they seem to be changing. So we've put together a post explaining the latest numbers and what's led to the changes.

(ed.note: To understand the bigger picture, here's a good piece from the LAT from yesterday which argues that there's a growing consensus that this mutation of swine flu is not as virulent as once feared. And here's a blog post by an infectious disease expert explaining why even if swine flu is very mild it would likely be hugely disruptive and a much bigger deal than the seasonal flu. The gist is that even if swine flu is no worse for each individual than the normal seasonal flu, so many more people could get it that it could put a massive strain on our health care system.)