Is an H5N1 Pandemic inevitable?

Bird flu is still getting a lot of press, with new reports every time an infected avian species is discovered in another country. This raises the danger to humans simply by increasing the population potentially exposed to the infected animals. But a pandemic won’t occur unless the virus changes enough to become transmissible from human to human.

Is that possibility inevitable, or is it another low probability event with great consequences that never comes to pass?

Frankly this is more a ‘fear mongering’ thing than any real issue… the avian flu is like any other widely transfered extra-human virus… it might or might not jump… people didn’t worry about DutchElm Disease jumping… and in areas that was certainly epidemic

I’m with fear-mongering.

According to National Geographic’s article on it, the H5N1 has been passed birds (or pigs?) to humans (widely known) but has not passed from human to human. While it is possible, I recall the article saying something up the line of “at this time, the H5N1 lacks the necessary code to pass from human to human.”

I’m at work and don’t have time to link to NG. I’ll come back to this tonight and find the cite if no one has by then.

Honest discussion of the issue is not fear mongering… the constant attention to a currently impossible pandemic is …

There are plenty of diseases that could whipe out humanity if it ‘jumped’ (became a human borne illness, that is it COULD be passed from person to person)… this is just an issue to ‘worry about’… that currently is nothing to worry about…

Frankly the concept of vacinating for the possible human varient avian flu is even more insane… as when/if it becomes a human borne illness it may or may NOT be close enough to the current varient for the vaccine to work

Like any other statistical probability problem, the answer is: Inevitable, over a sufficiently long period of time. Defining the term sufficiently long is a detail that makes the difference.

H5N1 has the press appeal of virulence among reported cases, often presented as a fifty percent mortality rate. That percentage has behind it some demonstrably false assumptions. Not every case of any sort of flu gets reported to anyone at all, much less to doctors able to contact the CDC, or WHO. If you don’t have sick leave, or health insurance and you get the sniffles and run a fever you go back to the duck ranch and put in a tough day. You don’t die, and no one cares what you have not died of. Keep in mind as well that hundreds of people dying of the flu on given day is not a statistically uncommon event.

“Making the jump” between species is a freak event that happens just about every day, for some virus, somewhere. It happens when two species share the same environment with sufficient propinquity to allow viral material to be ingested, breathed, or introduced into a wound by another individual. Billions of viral particles get introduced into the new species, and billions fail to reproduce in the new critter. So, we have to wait another five minutes for another group of billions to make the trip. Wait a year, and you have trillions of viral particles “attempting” to supply a new source of disease. And year after year, all those trillions of particles fail to do so. And while they are trying, quadrillions of other viral particles are trying it in other environments.

Yes, the possibilities are very small, but the numbers are very large. In a decade, it is inevitable that some virus will adapt to some human host. How virulent is that particular strain? Randomly virulent, of course. In a century, you get twenty tries for high virulence. Then you get to sieve the survivors for infectiousness. At that point the survivors survive, as survivors tend to do. Now its 1918, and millions die. Or is it 2018, and millions die?
Science, in particular clinical medicine has great power to deal with the consequences. Of course it takes several congressional committees and a number of academic institutions to harness that power, and viruses don’t have committees. Eventually a vaccine is available to increase the frequency of immunity to the disease. As soon as one of a very few corporations decides that it is profitable to manufacture the vaccine, you can begin the international political process of immunizing large populations. Of course you have to convince the population of 178 countries that America is not trying to poison them with vaccines.

Of course we are trying to poison them. But we cleverly put the poison in the cigarettes where no one cares.

Tris

Fear-mongering: In any emergency planning there a tough balance between “being prepared” and “fear-mongering.” There are many people that are being paid to work on this stuff, full-time, and we should all be glad there are, because that’s what’s required to be prepared. If we had more people “fear-mongering” about Katrina the damage wouldn’t have been nearly so bad.

I would point out that one of the biggest and scariest consequences of a pandemic is the general economic slow-down that will happen if people are unable or unwilling to go to work. If people don’t want to take public transit, if schools are closed, if people stop going to restaurants and the restaurant workers are put out of work, etc, the economy will be massively disrupted. Example: 44 people died from SARS in Toronto in 2004, but the economic impact was in the billions, and many many people (mostly in the tourism/hospitality industry) lost their jobs and have never recovered from that. And that disease was limited to health care institutions, nobody on the street was ever in the slightest danger from the virus. Public awareness campaigns can help enormously with this sort of stuff. If the public is not kept in the loop of what’s going on during an emergency, there is a very large risk of people getting scared and doing things that are counter-productive to the response.

People who do this kind of stuff full-time have to think about the worst-case scenario. That’s their job. They have to envision it, imagine all possible consequences, expect the unexpected, know the unknowable, etc. They have to. We do not. When the media picks up on some of their materials, and releases them to the public, of course there will be fear-mongering.

For instance, this article reports that you shouldn’t bury your dead too close to the septic system. This type of knowledge is fear-mongering, but shouldn’t we be glad that someone, somewhere, is thinking about this kind of stuff? I mean, I am quite glad that I don’t need to know how to store dead bodies, but I am glad that if the information is suddenly needed, it will be available.

Governments are then left in the unenviable position of having to say, on one hand, “Don’t worry, we’re prepared, it’s all good” and “Here is some knowledge that may save your life.” It is very difficult to do both.

A pandemic has to meet the following criteria:

  • Introduction of a novel (new) influenza virus
  • Highly contagious: human to human transmission happens easily
  • New virus causes serious illness and/or death
  • Population has little/no immunity

So by definition, it is (a) highly unlikely, and (b) going to have a huge impact (if it does happen). H5N1 is not a pandemic virus (it is not new) but as it spreads through the world and mutates more, the likelihood of it becoming a pandemic increases. By definition there will be no vaccine (because if there was a vaccine it wouldn’t be “new,” vaccines take time to develop and produce)

Yes, EEman, anything that met these qualifications would indeed be a pandemic, and would be something worth worrying about. How do you figure that it is “currently impossible”?

All we (as citizens) can do is cross our fingers and hope it won’t happen, and try to make our communities more resilient; all we (as emergency managers) can do is prepare for the worst and hope for the best.

The people being paid to work on these issues are not the ones who decide which ones get air time… and my comments are directed at the media more than anything… doing a quick Lexus Nexus search, this has been in articles for 18 months, with over 20,000 articles…

There are thousands of diseases that fall into this catergory… the ‘fear mongering’ comes from 18 months and 20,000 articles about a single disease that can not be spread amoung the human popluation

This is a fully known issue and handled via serveral agencies and regulations… and has not been in constant media spotlight for 18 months… if there were articles about what was going on, that isn’t fear mongering either… constantly discussing the possible issues if this paticular virus jumps species with no evidence that it has mutated in that manner… is worrying people for the sake of selling something… ala fear mongering…

Governments aren’t the ones keeping this in the spot light… but even if they were, what are they saying not to do? Don’t work on chicken farm in Rural China? … Don’t Process ducks in Tailand?

This is all true, but has no connection to the current avian flu… though the news media have some believe that it is seconds from becoming a new human borne plague… which has no basis in reality (it might, but then so might thousands of other strains)

Currently the Avain flu can not be transfered from human to human… and is RARELY transmitted from infected foul to human… it is currently impossible for this virus to cause any of the feared issues to occur… if it DOES jump, then it would be such an issue (as would… broken record time… thousands of other diseases)…

There is no way to prepare for the coming avian pandemic… you can’t vaccinate for the current strain and hope it will cover it once it jumps species… you can’t limit people from the current risks (more than is ALREADY being done)… you can’t do anything, UNLESS it jumps… there is nothing to worry about (well anymore than any other day)… and there is nothing to ‘do’… except what is already being done…

The fact that the average citizen is so scared of THIS strain of the flu, is purely to sell more papers…

EEMan, thanks for making yourself clear. I had cut-and-pasted a lovely and well-formatted reply to your message before I realized that we have no disagreement.

You are saying that the H5N1 virus, “bird flu,” is not worthy of the fear-mongering that’s been devoted to it. I completely agree, it is not.

I’m saying that pandemic influenza is something quite different, and if the media were giving it the press time that they currently give avian flu, I don’t think it would be fearmongering.

While the press and various other folks may be playing this up more than necessary, I recently attended a talk by one of the leading Infectious Disease experts in the nation, Dr. Dennis Maki. He feels we need to take this virus very, very seriously.

According to the good Dr. Maki (with whom I’ve worked for nearly 4 years now and never found to be an alarmist), this is not an issue we can safely ignore, and without some strategic planning, a pandemic is a real possibility even tho far from a certainty. He’s particularly impressed with the high mortality rate (over 50%) among those humans infected from birds with this strain.

So I guess it comes down to semantics. What do you consider a “low probability event”? If there’s even a 5% risk that the virus mutates with its virulence unabated, the projected death toll could exceed 5 million in the US. To me, a one in twenty shot of millions dying of this merits a lot of attention. How about one in a hundred chance?

My statistics might be off a bit… BUT I was under the impression the chance of any disease jumping and remaining as deadly as it was previously… is something like in 10 million or so

On preview, I withdraw my unposted response to your post cowgirl. Thanks for clearing that up.

Do you have a cite for that, EEMan? I’ll be the first to admit that my virology is rusty as hell, and that my day to day ID skills are pretty much restricted to the basic nuts and bolts of the more common diseases. But I seem to recall learning that vector infectivity shifts were felt to be separate phenomena from virulence. Therefore a change in vector would not necessitate a change in virulence.

If that’s wrong, I’d be glad to learn of it. It would mean we could certainly relax somewhat over this.

Of course, ordinary influenza just in and of itself is nasty, and kills 20 to 40 thousand Americans every year. But that statistic we all seem to take in stride. Maybe because it generally strikes down the very young, the infirm, and the elderly as opposed to those in the prime of their lives.

FWIW, and no cites, I had dinner in Beijing about a month ago with an ex dormie from University who now works for WHO in Beijing investigating H5N1 outbreaks in rural China. She was also based in China and investigated SAR’s when that happend.

#1 - see no evidence that the Chinese government is covering up bird flu. She does see under-reporting of infected/dead. So the incidents are reported but numbers of people under reported. Eg, testing shows the dead guy was bird flu, but didn’t test or “inconclusive” tests that his wife and 3 co-workers also died of bird flu. They just “happened” to die around that same time. :rolleyes:

#2 - no one “knows” whether or not it will jump to humans

#3 - no way to predict when the jump will occur - this year, next year, 5 years from now, never

#4 - no way to predict how bad it will be. World is a different place than during our past epidemics

So sayeth a WHO H5N1 investigator in Beijing. She has little kids and doesn’t stock tamiflu.

No, virologists do not consider it inevitable that the H5N1 virus will aquire the capability for efficient, sustained transmissibility between humans. What they do consider inevitable is that at some point, some influenza virus will do that.

Many virologists and epidemiologists have expressed their concerns about this particular virus in terms somewhat uncharacteristically strong for nerdy labcoat-wearing types, and in passing these concerns on to a popular audience, many media sensationalists have (as is their wont) chosen a tone best described as “shrill”. Be that as it may, the virologists and epidemiologists are concerned for some very specific reasons, and any hope of realistically evaluating the validity of those concerns lies in gaining at least some rudimentary grasp of those reasons.

Influenza is a profoundly contagious disease. Not only is it capable of airborne droplet transmission, but it is also contagious before onset of symptoms. The significance of this two-pronged threat is invariably overlooked by those who, wishing to minimize the threat posed by H5N1, attempt to draw parallels to other diseases which either require insect vectors or direct contact, or which are only contagious during the symptomatic stage. The H5N1 influenza virus is most definitely NOT like any of these.

Another thing that sets influenza apart from the “thousands of other diseases” mentioned above as potential candidates as pandemic-producers is the fact that viral replication in avian influenza is especially error-prone (roughly 100,000 times that typical of DNA replication). Each fresh batch of virions therefore includes a high percentage which are genetic “experiments” (most of which, lucky for us, fail). In addition, its genome comes packaged in eight segments, offering unique opportunities for an event referred to as “reassortment”. In a host co-infected with multiple strains of influenza, segments from each can (and do) end up getting repackaged as new, hybrid virions. Ebola can’t do this trick. Neither can Marburg, or measles, or mumps, or yellow fever, or rubella, or rabies. This is the event, long dreaded by virologists, that could cause a pandemic strain to erupt suddenly. Anyone currently offering to assign numbers (like one in ten million) to the probability of such an event occurring is pulling those numbers right out of thin air – but one thing that IS certain is that whatever they are, they are increasing as the virus becomes endemic (actually, it’s enzootic) in populations of both wild and domestic birds. They are significantly higher where instances of infection in humans with seasonal flu are widespread.

The significance of sudden introduction into the human population of a new subtype of influenza is also not easily appreciated by non-epidemiologists. Familiarity with seasonal influenza leads many to view flu as a mere nuisance; life-threatening perhaps for the very young, the very old, or those with underlying conditions, but not a serious disease for those with strong immune systems. (To make matters worse, the term “flu” tends to get applied rather loosely to any illness accompanied by sneezing, coughing and fever).

One of the broad subtypes by which virologists classify viruses in the family Orthomyxoviridae is by the protein spikes which protrude through their viral envelopes: “H” for hemagglutinin, and “N” for neuraminidase. There are nine NA subtypes, and sixteen HA subtypes – of which only the H1, H2, and H3 subtypes have previously been known to produce infection in humans to any extent. What this means is that the only humans on earth who have any immunological memory of this virus are the fewer than one hundred people who have contracted the virus and survived.

Another commonly made claim is that the current case fatality rate of over fifty percent fails to take into account large numbers of asymptomatic or subclinical cases. If true, this could be verified by testing for antibodies to the virus, focusing on those with whom known patients had contact. Epidemiologists are crying for more such seroprevalence studies, and of those which have been performed, access has been difficult; but Michael Perdue, a World Health Organization scientist working on the global influenza program, had this to say:
The evidence for widespread asymptomatic infections is just not there. The (more recent) studies that have been done, one of the reasons frankly that I think they haven’t been followed up on, is they haven’t found many positives. You don’t get too excited about all negative serology.

Having said that, it’s worth noting that “the people being paid to work on these issues” aren’t making projections based on the case fatality rate currently seen in the avian form of the virus; in fact, not even close. The consensus is to assume a CFR in a pandemic strain similar to estimates from previous pandemics, the 1918 Spanish flu pandemic being close to the “worst case” at about 2.5 percent (with an “attack rate” of around 30 percent). Let’s do the math: if 30 percent of 6 billion people get the virus, that’s 1.8 billion; if 2.5 percent of them die, that’s 45 million dead. If you call that fearmongering, consider that what they aren’t saying is that there really isn’t any firm scientific basis for assuming that the CFR won’t stay closer to what it is now. And that doesn’t even take into account the social disruption cowgirl mentioned.

Another thing the “people being paid to work on these issues” aren’t doing is making optimistic statements about their ability to actually do very much of anything about an influenza pandemic should one erupt anytime soon. Culling may work with chickens, but culling humans always raises a stink. Quarantine won’t work either (in fact, the whole idea is a joke). The WHO’s response to the outbreaks in Turkey suggest that by the time the “antiviral blanket” is ready for deployment, infected people will have de-planed in airports across the globe. Hospitals operate very near their capacities now, and surge capacity just doesn’t exist. There won’t be a vaccine until at least 4-6 months into a pandemic (don’t even ask how long it would take to produce significant numbers of doses), and supplies of antivirals are not even adequate to cover caregivers, first responders, and other essential personnel. Before “bird flu” started getting press, Roche complained that it could hardly give Tamiflu away, and robust supplies are years in the future (plus, we aren’t even sure if the antivirals will even work). There never has been much of a margin on producing flu vaccines, which is why half the US supply is imported… on a “just in time” basis, like most everything else (when borders are open, that is). And there is the real crux of the problem. It doesn’t even have that much to do with H5N1; it has to do with so many millions of people being so dependent on supply chains that are so efficient, but oh, so brittle. Half of what I ate for breakfast this morning was grown in another hemisphere. In addition, a lot of us wouldn’t survive interruption of pharmaceutical supplies alone lasting more than a few weeks, even if we never got the bug.

Does this mean that “there is no way to prepare for the coming avian pandemic”? No. It just means that just like pre-Katrina residents of New Orleans, there are limits to what we can expect from governmental agencies, public healthcare systems, and pharmaceutical manufacturers. If the CFR stays below (say) ten percent, the lights will probably stay on, and the toilets will still flush, but a lot of people will be wanting to stick close to home for a while. If the WHO announces phase 4, it’s going to suddenly dawn on a lot of people just what a good idea that might be, and the first thing they’re all going to do is head for the grocery store.

Not me, though. I’m all stocked up.

No, that’s just wrong. There is a high mortality rate among known cases of humans infected from birds. Known cases. But how many unknown cases might there be? How many humans have been infected from birds with H5N1 but never got sick enough to seek medical attention? We simply don’t know. For all we know, the true mortality rate might actually be quite low.

I suspect it is not just the desire to sell newspapers that prompts the fear-mongering. Should we not consider the possibility that health organizations are using H5N1 to scare up funding?

That sword cuts both ways. How many have been infected and died without ever seeing medical attention? How many unreported deaths have their been. For that matter, how many people contracted the avian flu and turned into fudgey brownies?

Best to stick with the hard numbers that we have instead of going by what may or may not have happened.

Firts: any successful pathogen musn’t bee TOO deadly-if it were to kill off its host immediately, then the transmission would stop and the epidemic halted. This means thta (probably) a very virulent strain would not get too far.
Second: the 1918 virus spread rapidly because there was a major war on, with millions of men travelling by train, ship, etc. Why didn’t the US Public Health authorities immediately halt all troop movements? It seems to me that I read once, that the epidemic came in two waves-one early in the USA, then the virus came back from Europe-and the second wave was the most deadly. This suggests that the 1918 virus did nutate in Europe, and came back as a much more deadly form. Is there any proof of this?

We don’t know, but we can guess. (Scientists call this “extrapolating”).

Sticking to hard numbers is the way to go, and if we had more serological studies, we’d have more hard numbers to stick to. But there are problems. The tests which are most reliable are also the most difficult, time-consuming, and expensive to perform. Perhaps most significantly, they are also politically sensitive, and the withholding of results is an ongoing source of frustration for epidemiologists. It’s hard to draw definitive conclusions from what we have so far.

In an article titled “Yes, but will it jump?”, the journal Nature quoted Yi Guan of Hong Kong as saying that that his team tested 4,000 people in southern China in 2001 and found no H5 antibodies.

But in an article titled Risk of Influenza A (H5N1) Infection among Poultry Workers, Hong Kong, 1997-1998 , Bridges, et al concluded:
Although no H5N1-infected [cullers] or [poultry workers] were identified among the 18 hospitalized case patients, the H5 seroprevalence rates of 3% and 10%, respectively, suggest that a substantial number of mild or asymptomatic infections occurred in these occupationally exposed populations.

If it is true that large numbers of asymptomatic or subclinical cases are going unreported, this isn’t entirely good news. It would mean that surveillance is even less reliable than we thought, and that the virus is being presented with even more opportunities for reassortment than we thought.

That’s true, but what counts is what epidemiologists call the “R-nought” number: the number of other hosts to which the average infected host will transmit the virus. Seasonal influenza rarely kills, but once the syptoms hit, an afflicted person isn’t likely to be out riding elevators or attending basketball games; if what you have really is the flu, you’re doing good to make it across a room without assistance. Once an influenza victim takes to his bed, the number of others who are in a position to catch the virus from him isn’t going to change much whether he lives or dies – and it won’t make much difference to the virus either, because most of the new cases will have already been innoculated during the *pre-*symptomatic phase anyway.

And the rest of the folks (the vast majority, actually) stuck much closer to home than most people do nowadays, since modern lifestyles typically involve much more commuting than they did then (much faster commuting, too). But in every little nook and cranny in the world – even in places where generations of villagers, living their entire lives within twenty miles of their birthplaces, may have hardly heard of the “great war” – still, the virus found them.

That is one possible interpretation of the available evidence. “Proof” is a pretty strong word.

The US Public Health Service was, essentially, a paper tiger in that era. Arguably, it was the 1918 flu that changed this.

Wilson wanted the troops in Europe right now. That’s why the movement wasn’t stopped. Either he didn’t understand the consequences, or didn’t care. No way to truly know, at this late date.