Here is a brief summary of what we seem to know now.
The World Health Organization reports that in the US there have been seven confirmed cases of Swine Influenza A/H1N1 in humans, wtih 5 in California and two in Texas. In addition, there are another nine spuspected cases. These were generally not severe, and no one has died.
Less traditional and less reliable sources have suggested that there are a large number of cases of type A flu (not necessarily the swine flue) in Queens New York, perhaps something like 100, and two cases in Kansas. If these are real, they will probably be reported by WHO and CDC over the next 24 hours.
In Mexico, there are three separate situations being reported. According to WHO:
In the Federal District of Mexico, surveillance began picking up cases of ILI starting 18 March. The number of cases has risen steadily through April and as of 23 April there are now more than 854 cases of pneumonia from the capital. Of those, 59 have died. In San Luis Potosi, in central Mexico, 24 cases of ILI, with three deaths, have been reported. And from Mexicali, near the border with the United States, four cases of ILI, with no deaths, have been reported.
Of the Mexican cases, 18 have been laboratory confirmed in Canada as Swine Influenza A/H1N1, while 12 of those are genetically identical to the Swine Influenza A/H1N1 viruses from California.
Swine flu us common, not surprisingly, in pigs and passes to humans fairly often. There is a low level background of swine farmers getting the swine flu … and getting sick enough to notice it (many more may get infected but don’t become ill or mistake it for a cold). Rarely, swine flu shows up in a form that can pass between humans.
Flu evolves (if that is the correct term) by exchanging large sections of genome back and forth during its life (if that is the correct term) cycle. A flue can be constructed of bits of avian, bits of swine, and bits of human flu, for instance. A combination of swine and human flu may have the property of transmission between humans and some added virulence (because the swine part is new to the immune system). This particular flu seems to be a combination of swine and human as well as avian components.
One alarming feature of this flu, if confirmed, is that it seems to be worse in healthy prime age individuals. Now, don’t get too worried about this yet, but this could be a problem. This was the case with the 1918 flu, which infected half of the human population and killed millions. The so called “Spanish Flu” was a combo of human and avian genetic components. It killed by causing an overreaction in the immune system. The healthier you are, the better your immune system. The better your immune system, the more likely that flu would kill you.
So you can see why health officials are worried about this flu. You don’t have to worry yet, though. This could still fizzle out. Just keep an eye on things.