Reader’s Question: Bird Flu has hit the UK. I was just needing some advice (not from the tabloids and news) about the medical affects on humans. What do you think is going to happen? This could be advice or just a general comment.
Reader’s Answer: The flu virus family is a big one. Some are characteristically bird flus, others are swine flus, others are human flues …
There’s a considerable similarity amongst them (a family, right!) and under some circumstances, a bird flu can swap bits with a pig flu or a human flu, producing a new variant. It’s likely that Hong Kong flu?) in humans get started.
Usually, bird flus don’t bother people or pigs, and vice versa. But sometimes, there’s enough of a crossover that a bird flu acquires the ability to infect people and spread easily. It happened in 1918, and that flu epidemic spread rapidly and killed something on the order of 40 or 50 million around the world in about 18 months. We know it was a bird type flu because the virus has been reconstructed in a research lab. These guys went looking for folks who’d died from that flu in the Arctic North and been buried in the permafrost. It took more than a decade, but it’s recently become clear this flu, the ‘Spanish flu’, was a bird type flu.
in the case of the current avian flu, it’s not yet (if it ever will) acquired the ability to spread easily from human to human. It seems that you must be in close contact with infected birds to have much of a chance of catching it. But if you do, it’s very dangerous. The mortality reat in the first few hundred reported cases was something like 50% and that’s very very high. More recent cases in Europe seem to have a lower mortality rate, but that may primarily be an artifact of better care (eg, learning from prior cases).
There is little understanding of what changes would be required for this bird flu variant to become human infectious. There has been some speculation that it may be a few as two different gene changes. And perhaps the change(s) will never happen; no one has much of a real idea about the chances. And it’s possible that, if it becomes infectious in humans, it will lose the lethality it currently has in humans. Or not, which is the scary case.
Treatment for flu viruses is traditionally best via vaccine. However, since flu viruses change regularly and the vaccines are typically variant specific, it hasn’t been possible to get it precisely right. Which variant will be the major issue in the coming flu season is hard to predict, but having guessed, it takes quite a while to produce the vaccine. It’s a bit of a guess and isn’t always gotten right. The avian flu is no different.
A vaccine against the current variant would be pointless for humans, as it doesn’t infect us very well. And if the virus changes to become infectious in humans, we don’t really know how to develop a vaccine against a virus variant we haven’t yet seen. And after we see it, it will take some months to produce the vaccine for it.
What are the chances of drug treatment against a human infective variant of this avian flu? Not good, just as there aren’t very good drugs against any virus infection. We have one or two drugs, of which Tamiflu is thought to be the best of a not very good lot. Governments have begun stockpiling it, against possible need.
Avian Flu possibilities:
1) The virus never acquires the ability to infect humans easily and to be highly contagious. If so, the current plague among birds will eventually burn itself out and there won’t be much further issue.
2) The virus will never acquire the ability to be highly contagious, but will learn to infect people much better than it can manage now and will retain its lethality. More people will die before the pandemic among birds finally burns out. Death toll might be in the thousands or hundreds of thousands, as compared with hundreds to date. it think this unlikely as the flu viruses have all had excellent contagious properties.
3) The virus will acquire both the ability to infect humans readily and to spread between humans easily and will keep its lethality among humans. This is the really really worrisome possibility.
Judging by the 1918 pandemic, lots of people will die, and quickly. That episode lasted something like 2 years or so and spread much more slowly than it can now. The SARS outbreak a few years ago jumped continents in only a few hours. If this projected variant travels the way SARS did (airplanes, most quickly), the 1918 pandemic will look like a picnic.
My own guess is that the death toll directly from the flu variant will be in the hundreds of millions, and indirect death from the disruptive consequences of do many direct deaths (cholera, typhus, typhoid, etc etc) will be very bad as well.
A vaccine will eventually stop the epidemic, perhaps before it burns out on its own, but that will take some months at a minimum. And the distribution problem will be tough, very tough. We can’t even vaccinate all the most vulnerable against the usual flu and that’s with no emergency at all. The non-developed world will have even more trouble.
4) The virus learns to infect humans and to spread rapidly among them, but loses its lethality in humans. Perhaps down to that of regular flu, which is actually quite dangerous. It’s not just a bad cold, people. Anyway, if this happens, we’ll just have a really bad flu season, many thousands will die, but not much more will happen. Not good, but we can cope with this, probably.
A vaccine will be necessary, will take months to develop, but will keep death rates down afterwards.
Avian Flu Source(s):
On these questions of dangerous diseases springing up out of nowhere, you might find Laurie Garret’s work of interest. The most relevant is the Coming Plague. Well written, well researched, well done. Her book on public health services is also excellent.
Wm McNeil’s Plagues and Peoples is an early treatment of the historical consequences of plagues from the Ancient world to recent times. The data we have, for the last few hundred years of the Roman Empire in the West, for instance, are skimpy to say the least, so much of this is extrapolation, but it’s fascinating stuff. McNeil was the Chairman of the Hisotyr Department (Committee) at the University of Chicago.