All I can say is that it's a good thing Canadian Press's Helen Branswell isn't a blogger or she'd put all the rest of us flu bloggers out of business. She is the professional flu reporter's professional (one of the best of the flu reporters once described a story of hers to me as "annoyingly good"). Being in Canada she also has more of an international perspective, as in a recent story about differences between seasonal flu in the US and Canada this year, a story that would have escaped the notice of US based reporters (hat tip to crof):
Maps generated by the Public Health Agency of Canada and the U.S. Centers for Disease Control and Prevention show widespread flu activity in 49 U.S. states, but in only one province, British Columbia. Other parts of Canada are experiencing localized or even sporadic outbreaks; some may be past the peak of their flu seasons.[snip]
The main viruses causing disease so far this year in Canada are H1N1s that are closely matched to the one included in this year's flu shot. So people who got a flu shot - about a third of Canadians do - are well positioned to ward off assault from those viruses.
But in the United States, a recent surge in H3N2 activity has made those viruses the most predominant cause of illness this year. The H3N2 viruses circulating are not well matched to the vaccine. (Helen Branswell, Canadian Press)
Canada is experiencing a very snowy and cold winter, at least in comparison to a string of mild winters over the last decade. Since I am in Canada at the moment I can attest to its cold and snowiness. But it doesn't have (yet) a lot of flu, although flu is widespread in the US. Again, it hit close to home. Mrs. R. and the daughter have it (I had a flu shot and so far . . . ). We started out the year with most cases being H1N1 subtype, one of the two influenza A subtypes that co-circulate and one that is usually associated with milder seasons. But in January there was a sudden upsurge in H3N2 cases, now becoming the predominant subtype in various regions. This has yet to happen in Canada although it could still switch over. Flu season is usually over with by April, but March is expected to be cold and snowy in Canada, plenty of time for H3N2 to take hold there.
In the meantime Canada and the US are exhibiting different patterns of severity and circulating subtypes. On the one hand this isn't a surprise because even regions of the US exhibit different patterns when considered at single points in time. On the other hand, saying we aren't surprised is nowhere near the same thing as saying we understand it. The dynamics of flu spread and subtype mix is poorly understood -- if we can say we understand it at all -- so perhaps the most surprising events are the ones we correctly predict and aren't surprised by.
Sort of like the town that has a barber who shaves everyone who doesn't shave himself. Does the barber shave himself? (Think about it.)
- Log in to post comments
There is too the newly posted report in PLoS ONE showing a few of the H5N1 strains circulating in southern China were somehow blocked from entering Indochina. Public and animal health decisions at the national (or provincial) level can shape the evolution and spread of influenza. To wit, human pathogens evolve in response to the world we make.
You forgot to specify that the barber shaves ONLY those people who don't shave themselves. The way you stated it, the barber could well shave himself without logical contradiction. With the ONLY added, the question is undefined... after all, it is possible to not need to shave at all.
speedwell: Your point is that if the barber shaves everyone who doesn't have themselves, then he might also shave people who do shave themselves, including himself. True. I made the tacit assumption that a person only shaves once per day, either by himself or the barber and of course everyone shaves because ifyou don't the barber will shave you. Whether the question is defined or not depends on what you mean by problem definition. The usual answer to this antinomy is that there can be no such barber (which to me is different than an undefined question, which I would take to mean something more like a partially defined map). The usual solution to this problem comes from Russell's theory of types, where it is of the form of "set of all sets" predicates which leads to the same kind of antinomies).
pathogen rex: Evolutionary theory says that the virus evolves in a world that humans alter but not in response to it. In classical evolutionary theory (which so far pertains here, too) the virus changes randomly (by one of several mechanisms) but the change is not forced by the world, only the outcome is forced by the world (i.e., whether the change allows the virus to replicate). The onrushing train of epigenetics is bound to modify this but that's the picture so far.
The barber is a she.
CRN: LOL. Could be. That adds some complications to the problem specification.
revere, please, you took what was clearly shorthand on my part as an opportunity to pretend an expertise. "Evolution" includes by natural selection to the conditions we set. When strains favorable to the world we create emerge, "response," despite its anthropomorphic connotations, is a reasonable characterization.
Barber has a beard. . .
give us the sequences and the patients questionaires
and we will tell you how flu spreads.
pathogen: I apologize if you took my response as condescending. I responded that way for a particular reason. There are many who read this site who believe that antivirals (to take one example) actually cause the virus to mutate and they speak in ways not distinguishable from you shorthand. Clearly you didn't mean that.
The barber lives *outside* the town, and is therefore excluded from the set of people either shave themselves or are shaved by the barber.
Samantha and others: The barber paradox can only be "solved" by changing the problem as you have done. Otherwise it is a true paradox that requires a more structural solution, for example, that you are not allowed to have sets that have themselves as members if it is all sets. The form of these paradoxes is similar, whether it is this one, the "all cretans are liars and I am a cretan" version or the library card catalog one, etc. It is a deep problem, not a superficial one and occupied some important logicians and mathematicians early in the last century.
revere, apology accepted. Your excellent question, however, went largely unaddressed. With all due respect, my fellow posters seemed more interested in shearing each other's Godelian pubes (although the touch of Todd may have done the rest of us wonders--ha!). We know that during 1918 some U.S. cities were hit less fiercely than others, if only by dint of the seriousness local public health departments took the threat (rather than the nature of the virus itself). But a la Boots and Sasaki, lesser transmission both within and among epicenters may have had consequences for the evolution of local virulence. So geography matters, even for a virus that laps up the miles down the socioeconomic hierarchy of cities. The PHA/CDC and PLoS ONE reports show us something of a similar picture but from the virus's viewpoint.
The barber is a she with multiple personality disorder, one of whom has a beard?