I was up far too late last night watching football, and our DSL was down during the crucial hours between work and Monday Night Football, so I couldn't pre-write any blog posts. Which means you get sleep-deprived idle thoughts as blog posts this morning. I blame Verizon.
So here's a question about medicine, or rather the media coverage of medicine, that has been bugging me. In stories about the bird flu or whatever, you'll frequently read statements of the form "We're closer to having a worldwide pandemic than at any time since 1918."
My question is, in what sense is that true? That is, is the presence of a fatal-to-humans strain of avian influenza in some regions of Asia really a unique occurrance, or does it just seem particularly ominous because public health reporting has improved enough that we actually know about the situation in advance?
It seems a little odd to think that there hasn't been any time since 1918 when there was a potentially devastating bug lurking in a rural area somewhere, killing those unlucky enough to get it, but not quite making the jump to airborne transmission and getting out into the wider world. That seems like the sort of thing that probably happens more frequently than we know about, just because there are so many remote parts of the world where medical care is rare and disease tracking impossible. Lots of rural farmers could have died of mysterious diseases that could have become the Next Great Plague, but didn't, and we'd never know.
So is the current scenario really a matter of a new and uniquely threatening bug, or is it a common bug and our knowledge of it is the new and unique thing? If a bird gets the flu in a forest, and no doctors are there to record it, is it a potential pandemic?
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I think it's mostly knowledge. We've only known about the relative dangers of various virus subtypes (and been able to type them in meaningful time) for a relatively short period. It wouldn't surprise me if a similar situation to today had existed many times in the past. Of course, there's always population density and mobility to contend with, which makes today's situation more dangerous - but you can probably cancel that out with modern public health infrastructure as compared to the old days.
Overall, I think that bird flu is potentially dangerous, bears watching, would be prudent to lay in some preparation for, but is nonetheless grievously overhyped.
Think earthquakes. We know that the _longer you go_ between earthquakes in an area such as California the higher the odds of an earthquake in a given year. You can look at measurables such as earth strain and fault creep and actually get a fairly good idea not only of the increase in probability, but also where it is most likely to hit. You just don't know exactly when.
It has been a _very long time_ (as such things are measured) since the last major flu epidemic and we know that almost all of the factors required to spark a major pandemic are coming into place.
We have a largely fatal variant that shows signs of becoming human transmissible - we even have a decent idea of where it is likely to start (Indonesia and nearby countries are the prime candidates due to their livestock practices and poor public health systems) and what genetic changes are needed for the virus to become a pandemic.
We just don't know exactly when it will happen: It could be this week (not really likely) or within the next two years (ranging upwards towards likely) but we almost for sure won't make it to ten years.
Well, that's not quite right. We've *had* pandemics since 1918: in 1957 and 1968. Looking back at history, we know that pandemics resurface in the human population. It's been almost 40 years since the last one (and 50 years since the last big one; 1968 was rather minor), so there's a lot of nervousness that the next one is really going to kick our collective asses.
So that said, I think it's a bit of both of what you mention. One, we now know by studying the 1918 virus that avian viruses can jump right into the human population without reassorting with another virus (the 1957 and 1968 viruses were reassortants), so that makes the current H5N1 situation alarming. Two, we do have better surveillance, so yes, we're picking up viruses we may have missed in years past. Whether H5N1 becomes pandemic or not, this is invaluable data: we've never had the chance to examine the epidemiology and evolution of a highly fatal, but currently non-pandemic, influenza virus previously.
Personally, I don't like the "we're overdue for a pandemic" language, though I largely agree with the sentiment. It's just too hard to explain to the general public that while we think one will come eventually, we can't say if it will be a year or a decade (or more) away, and we can't say if it will be H5N1 or a different strain altogether (and we've found humans infected with other avian strains besides H5N1 in recent years).
Finally, though, I disagree a bit with Derek's statement:
Our public health infrastructure is badly damaged, and in countries such as Indonesia and others where this is simmering, fuhgetaboutit. Even our modern hospitals are swamped during a normal influenza season; a minor pandemic will stretch many to the breaking point, and a serious pandemic will simply overwhelm them. Overall, I don't think we're much better off than in the mid-century, and as far as treatment, we don't have a lot more to offer than in 1918. Vaccines, of course, would be the ideal, but we're still far behind on those as well. So I guess I'm a bit more pessimistic.
I am a physicist not a doctor, but I have read The Great Influenza by John M. Barry which tells the story of the 1918 pandemic. It is a fascinating blend of history and science, that I would recommend to anyone.
Influenza is inherently airborne, and it spreads before symptoms appear. It is very hard to quarantine. The pandemic of 1918 was distinguished by how virulent it was and that it killed the young and healthy more than the old and frail. I don't believe to this day that it is understood why it was so virulent, but there is some thinking that a virus that successfully jumps species is more deadly. A virus that lives in a population for awhile tends to lose its virulence.
This species jumping is what drives the concern about bird flu. Remember their were many concerns about swine flu about 30 years ago that were not realized. If there is to be another influenza pandemic like 1918, it is mostly likely to be caused by a species-jumping flu virus, but most species-jumping flu viruses do not cause pandemics.
"If a bird gets the flu in a forest, and no doctors are there to record it, is it a potential pandemic?" Yes, just like somewhere out in space is the next big asteroid destined to hit the Earth if no one nudges it aside. Yet even closer are more asteroids we can track and wonder about specifically right now.
The current concern is much like what got 40 million Americans innoculated against the swine flu in 1976. A soldier at Fort Dix died with an H1N1 flu, the same markers as in 1918. In 1976 it wasn't clear where it came from. It also wasn't clear why this didn't spread into a pandemic. Some might credit the vaccinations for that, but vaccines aren't that perfect. If the vaccines had let us dodge a bullet there would have been some disease to tell us that. Instead it was just a prudent thing to do, like an evacuation for a hurricane that turns away and doesn't hit the area evacuated.
Now there is more knowledge. There are many human deaths in Asia from this H5N1 flu and much more disease in birds with the same virus to show where it's coming from this time. This virus is not going to disappear into the background as easily as the 1976 virus did. Still it might not be a pandemic.
In both 1976 and now there is a clearly deadly version of the flu virus on the loose. It is better established in both animals and humans today than it was in 1976. That doesn't mean there will be a pandemic now when there wasn't one then. It doesn't mean the opposite either. The clearly deadly virus is documented, but how much will it spread? It's not just a matter of meteorology.
Experts can speculate on how living conditions decrease the risk of pandemic or modern travel increases the risk. It's just speculation. No one knows the right way to quantify something not previously studied well with this particular virus. It's known there's a killer virus, not something common. It's not the first one. It's not the last one. It seems that health organizations are being prudent about it, as they were in 1976. Media meanwhile are sensationalists. It's all understandable.
Whenever the question is, "Is this danger/threat overhyped?" you can bet with a high degree of certainty that the answer is yes. Because scaring people gets their attention and allows you to sell the sponsor's product, ask for more funding, do away with habeas corpus.
I blame 24 hours news reporting, the internet, and Republicans.
MKK
Well, a number of things have indeed changed over time, but they're more quantitiative than qualitative. Populations are larger and denser all around, and we've got a few new health issues for the flu (or any other pandemic) to interact with (HIV and MRSA come to mind).
Water supplies are more stressed, and food distribution more centralized. For that matter, goods distribution in general is more centralized and probably more fragile. International and internal travel is more common and quicker, at least until it starts to collapse.
(It occurs to me that all of these fall under the heading of "ecological issues", and specifically, more stress on the human ecosystem.)
On the other hand, we also have better medical technology, better communication, and more knowledge about what's going on. The question is whether that will be enough to offset the liabilities. I'd say political readiness and public education are close to a wash, with maybe some advantage to the present. And we don't have a World War going on at the moment....