I have been remiss in keeping up to date on this year’s doomsday viruses. As I posted earlier, mutant killer viruses are kind of a hobby of mine. Topic for today: flu.
Note: This turned out to be a longer post than I had intended. Its also, uh, kind of different in tone from the rest of this blog; there’s information and not a lot of goofy funny stuff here. I sort of got carried away writing it (too much time on my hands). I apologize and I will try and post short stupidity for the remainder of the day.
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Influenza is the lurking demon of viruses; For most of us when we get the flu we just end up ghastly sick and are forced to watch bad TV for a few days. But the flu can be worse than that — it still kills 36,000 people in the US every year, mostly the very old and the very young. Its more dangerous than it looks. Flu’s real danger, however, is in its ability to mutate; it can readily change through both antigenic drift and shift.
Drifting is what happens to flus all the time. When the flu drifts it becomes slightly different from its parent strain. This is why you can get flu over and over again; you may have immunity to one strain but not to its drifted cousin.
The bigger problem with flu is in antigenic shift — where a flu virus mutates into something entirely different and possibly really really bad. This is what happened in the 1918 flu, the Spanish flu, where somewhere between 20 and 100 million people died (we don’t know more precisely because they didn’t keep records in populous countries like India and China).
A flu virus can most commonly mutate when it comes in contact and combines with with a flu from a different species. Humans can contract bird (avian) flus, and pigs can get both avian and human flus. Its suspected that the 1918 flu came from pigs, or perhaps shifted from birds to pigs and then to us. It was the fear of another mutated virus from pigs that spawned the whole “swine flu” panic in the 1970’s.
Avian flu is raging through Asia right now, and has been for some time. Birds, and particularly chickens, are getting a particularly nasty version of avian flu that can kill as much as 90% of the population it infects, and farmers are culling their animals in an attempt to control the virus. 100 million birds have died in asia as a result of the flu, either from infection or from culling.
This avian flu is also spreading to humans. It has killed 30 out of 42 people infected in southeast Asia so far this year (a significantly higher mortality rate, to put it mildly, than the current .1% that human flu has today). The good news is that you have to be living in close contact with birds to get it (you don’t get it from eating chicken, for example), and the avian flu does not readily pass from human to human once humans contract it from birds. Control the birds, and you can control the flu. There’s also a vaccine, although it has only just started to be produced and certainly has no distribution in developing countries or rural areas where people are more likely to be found close to infected birds.
The fear, of course, is that if an avian flu passes to a human and combines with a human flu in the wrong way, it can produce something really horrible: extremely infectious and with a very high mortality rate — and it could spread and kill people really rapidly before a vaccine is developed and long before there’s time to distribute it. In the 1918 flu there were stories of healthy adults being fine one hour and then dead the next, drowned, their lungs full of fluid from the infection. What fun.
The big news in the last few weeks has been that a case of avian flu has appeared in Thailand that appears to have been transmitted human-to-human, from a daughter to her mother. This could be a very rare case of human to human transmission of avian flu (it happens), or it could be a new mutation of the virus that more easily infects humans. The WHO is still testing the flu strain the mother has to see if it is a pure avian virus or one with human components. The former is much less worrisome than the latter. We’re still awaiting the results of that test. In the meantime, no other cases of avian flu that can’t be linked directly to birds have shown up, so for the time being, as far as we know, there’s no doomsday flu on the horizon. And unless you’re planning to spend a lot of time hanging around chickens in Asia, right now you’re OK.