Why are we so nervous about bird flu?

I understand that there’s the possibility that it could mutate, and become passable between humans (as opposed to bird-to-human, where we are now). But isn’t it possible that the mutated virus could be no more virulent than the average run-of-the-mill flu that everybody gets every winter? Do we know for a fact that it would be a killer?

As I read it, there have been some cases in which people got avian flu, from eating infected birds, and died. It apparently doesn’t transfer, yet, very easily from animal to person, but if and when it does, it may stay as virulent as it has shown itself to be in those fatal cases. Without ample vaccines, it could make one nervous, no?

The fact that it is a new strain in humans means no one has antibodies for it. This can can result in an astonishly high death rate as the immune system causes the lungs to fill with fluid. This was the case with the 1918 flu pandemic. One of the articles I read on that recently stated that nearly everyone on the planet was exposed save for a few isolated islanders so that the same strain wouldn’t be as deadly.

Not from eating infected birds. Practically all of the victims have been poultry workers – or their immediate family members. (Or people who were exposed to live birds in close contact, like a live poultry market in mainland China.)

Some people are confused by the fact that family members have gotten sick without coming into close contact with the birds themselves. Doesn’t this prove that it can already spread from human to human? No. It seems as though only birds shed the viable virus at levels that are cause for concern. (Eg; the family members that got sick probably didn’t get sick from infectious exhalations, etc – but from contagion brought home from the farm on clothes or something.)



I’ll tell you why.

Because there is a whole messload of reporters chomping at the bit to use the ol’ copy-and-paste on their SARS articles again.

Leaves them more time to attend their super secret Liberal Media meetings where they conspire how to pin everything on Bush!

In cases where humans have caught Avian Flu there’s been a 50% fatality rate. So far Avian Flu cannot be passed from person to person (the people who have caught it did so directly from infected birds). But flu viruses mutate constantly and the concern is that the Avian Flu virus might mutate to become more infectious without mutated to become less lethal.

If you read actual reports from Scientists studying the dangers of pandemics (not the media or political stuff), they are very, very worried about a lot of things.

The stats basically say that in the very near future Something Real Bad is going to break out globally and kill 10s of millions quickly. Even in first world nations, the medical system is not capable of providing even “dignified death and disposal” for that number of victims. I.e., most victims will die at home without useful treatment.

SARS, contrary to being overblown, demonstrated how devasting such an outbreak could be. Whole hospitals in Hong Kong and Toronto were closed off. The medical services in those cities were significantly impaired for weeks. The majority of elderly people who got it died. And that was a small, well managed outbreak. If you multiply by 10 the number of victims you no longer have a functioning health care system. Now multiply by another 10, another 10, etc. Very scary.

The reason bird flu is getting a lot of news is that it is “Number 1 with a bullet” on the watch list of possible pandemics. If something is the number 1 threat, you make that your number one priority. No scare, no hype, just reality.

OTOH, West Nile is hardly worth mentioning at all. Low infection rate, low illness rate, very low mortality rate. More people die from stepping on rusty nails than from West Nile. It’s not newsworthy.

It’s probably worth noting that this was 50% of reported cases. There may well have been milder cases of the flu in which no one died and no one reported an illness that didn’t do much harm.

Because we are all going to die!

National Geographic mentioned that the descendants of the Spanish Flu are now some of the milder flu bugs around.

Sorry but you don’t know what you’re talking about. In this case pretty much the entire infectious disease community has been going apeshit over this bug for about a year, with virtually NOTHING in the press. It took politicians (god help us) starting to make a stink about it for the media to pay attention. Yes, that’s right the politicians listened to the scientists and the media listened to the politicians. Go figure.

The nature of viral zoonosis makes it probable that some virus will survive introduction into a new host species. That happens all the time. The factors that make it happen more often are the number of contacts between the species, and the presence of viruses that have similarities with viruses that have made the jump before. There are a lot of chickens out there, and a lot of folks who spend time around them.

H5N1 is a type of virus, not a specific virus. Members of that category have made the jump to humans before. It is likely that the 1918 influenza virus was an H5N1 virus. H5N1 is endemic in birds, although in many cases not lethal. Humans have contracted the current H5N1 virus from chickens about a hundred and twelve times in the last several years, and in at least two cases, passed it on to another human. Among all the recorded cases, roughly half (57) have died. There is no real way to ascertain how many cases of H5N1 have occurred in which symptoms were mild, or at least not lethal, since even in very wealthy countries, not everyone goes to the doctor every time they have symptoms of a cold. It is very unlikely that there are no such cases, but also unlikely that they are common, now that the likely population is under fairly close observation by health practitioners.

So, we have what amounts to a statistical certainty that some virus will cross to humans, and adapt to human to human transmission. We have a specific candidate that has demonstrated that possibility with an apparent virulence able to kill up to half of those who catch it. (That probably represents an upper bound, and an unlikely one at that.) The big variable that has not been determined is the communicability of the one virus example that makes the cross. You measure communicability by the number of persons on the average that can expect to be infected by each new victim.

Existing human resistance to avian source influenza is low, since there are essentially no survivors with antibody responses to the virus. (Think of it like measles among New World natives, in the 16th century.) So, once the event happens, communicability will be more of a question of propinquity than resistance. And with modern travel patterns, geography won’t be much of a barrier. So, a disease that a tenth or half the world might catch, that might kill 10 percent of those who have it. That’s from thirty to three hundred million dead in a year. That’s why it has people excited.

However, the numbers crank in lots of different directions. The virus that successfully makes the jump to human to human transmission might be much less virulent. Or the virulent strain could be much less communicable. What is certain is that it will happen, and it will happen over and over again. “Flu Season” is what we call it. The variables are just a bit wider than most of us expect.

Like Super Volcanoes, Tsunamis, and Meteor Impacts, these things are inevitable, but only on a time scale longer than an average human life. They could happen tomorrow, but they might not happen for a century. In the case of a very virulent viral disease, it is much more likely that it will happen in less than a century. The probability goes up when the population gets larger, and travels more.


Just to answer the OP’s question. Bear in mind IANAD or anything else, but I’ve been keeping up with this for the past year, so any expert’s corrections etc welcomed. Here, however is the nightmare scenario as has been outlined by epidemiologists:

You’re right it could (and probably will) be less lethal than the 50% number that’s being bandied about right now - but nobody really knows. But realize the regular flu that we get every year has a death rate of on the order of 1% or less and still kills 36,000 people in the U.S. annually. That’s with the existing strains being not particularly lethal and with most people having some degree of immunity to it. Even at that rate we often get a swamping effect in the hospitals where there just isn’t the capacity to deal with it.

So what happens if there’s a new strain introduced into the population? Well, for starters nobody’s immune to it so it will likely expose a very large percentage of the population rapidly and a lot of those people will die with no immunity. It’s impossible to tell how many at this point but it will certainly be a lot more than the typical 36,000. The hospitals have no hope of being able to provide critical care for most of those people (for one thing about all the respirators that we have are currently in use for the people that need them right now). You’ve heard of course about the shortage of antivirals and the delay in creating vaccines, too. So the upshot is “modern medicine” will have little impact on the death rate just because it won’t be available to most people.

Then there’s “collateral damage” which is just as scary. With many people ill and many deaths worldwide and a likely panic causing many to stay home from work, the world economy is predicted to come unhinged at least temporarily. Bear in mind that we live in a just in time economy, so that means that the things we need aren’t warehoused anymore. There’s no slack. If they’re not being manufactured all the time, they don’t exist. So there will be shortages or outright absences of absolutely everything - food, medicine, etc.

The economic effects may be worse than you’d think because it’s entirely possible that this flu will hit the working-age population harder than any other group. In 1918 people ages 20-39 were the hardest hit group and I believe I read somewhere that 6% of the population that age died in the U.S. during that pandemic. Whatever the exact number they certainly died in much larger numbers than any other age group. That may seem counterintuitive, but the speculation is that it is in fact precisely the stronger immunity of young adults that killed them in 1918 - the thinking being the virus may have caused a massive cytokine response which essentially flooded the lungs, causing an acute respiratory distress syndrome. It’s not clear that this would happen with this flu, but there are many who think this is a similar strain and could act the same way.

Now of course that is the nightmare scenario. Nothing’s certain except there will be a flu pandemic at some point and it will have a major impact. It won’t be like an ordinary flu season. There’s also good reason to think that this strain - the H5N1 strain - is likely to be the one. If nothing else because there’s just * so many* sick chickens in Asia, and the thing is clearly mutating and starting to affect humans.

  • Uglybeech, here to spread panic and alarm :slight_smile:

I see on preview Trisk has posted a very nice explanation

There are two books I’ve read that discuss how plagues emerge and what kind of impact they might have. The Coming Plague and Virus X. The author of The Coming Plague, Laurie Garrett, has also written another book about the problems we’d have if we ever ran into a really bad virus and the problems medicine has already mismanaged. I haven’t read that yet, but it’s been recommended. Richard Preston’s books, like The Hot Zone, are less academic but still give you the basics about where viruses come from and how they spread. The same mechanisms that apply to Ebola apply to influenza viruses, or any other for that matter.