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October 09, 2005

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You can't project from 1918, a bad year generally for health, can you? Or from the mortality rate among people infected by a new disease and hence likely to have weaker immune systems?

Anyway, having read Connie Willis's _Doomsday Book_, I'm not looking forward to this.

rilkefan: well, no, you can't, really. It's just that there is nothing obviously better to do. (And a large part of why 1918 was a bad year had to do either with the influenza itself or with the First World War, which I'm not sure would have figured into e.g. the attack rates for Spanish flu.)

And a virulent strain of H5N1 would be a new disease, at least outside those parts of SE Asia in which it might now be evolving, so it is in that respect comparable.

rilkefan: "Nearly half of all deaths in the United States in 1918 were flu related. Some 675,000 Americans -- about 0.6 percent of the population of 105 million and the equivalent of 2 million American deaths today -- perished from the Spanish flu. The average life expectancy for Americans born in 1918 was just 37 years, down from 55 in 1917. Although doctors then lacked the technology to test people's blood for flu infections, scientists reckon that the Spanish flu had a mortality rate of just less than one percent of those who took ill in the United States. It would have been much worse had there not been milder flu epidemics in the 1850s and in 1889, caused by similar but less virulent viruses, which made most elderly Americans immune to the 1918-19 strain. The highest death tolls were among young adults, ages 20-35." (cite)

Thanks for your post. Readers may also want to visit my site, H5N1, which focuses on flu-related news stories from around the world, with occasional comments.

Thanks -- here's a link.

How many of those 20-35-y-o's were soldiers in Europe? (stupid ISP) Born in 1918 seems weird to me, if the bad was in the above age group. Did the life expectancy then shoot up? (Angling for a claim that the flu culled the immunocompromised.)

I'm guessing that Asian populations have some immunity following the same mechanism described above?

rilkefan: I'm reading 'deaths in the US' as excluding deaths of Americans in Europe. I believe one of the initial outbreaks was in a group of soldiers training to go there, but they hadn't left yet.

It was an odd flu, since it did not hit the very old and very young preferentially.

And I assume that the 'born in 1918' life expectancy figures reflect a lot of dead infants.

From what I've read, mostly on Effect Measure, H5N1 can be worse on young adults than the very old. Unlike regular flu, it can attack organs by itself and may possibly kill by starting cytokine storms in a victim.

"Angling for a claim that the flu culled the immunocompromised."

Warning: Wild-a$$ speculation ahead: Given that young adults, rather than the very old or the very young, were most likely to die in the 1918 flu epidemic, I'd suggest that the 1918 flu culled the most immunocompetent, not the immunocompromised. In other words, the flu probably set up an immune reaction that was so severe that it killed a lot of people. The old and young may have had less extreme immune responses and therefore been more likely to survive. If this is true, the existence of drugs like prednisone and others that decrease cytokine response may help make the coming pandemic less deadly than the 1918 epidemic. I hope.

While we're speculating, I wonder if, in fact, some version of the H5N1 or similar flus might not already be present in the US, but in a very attenuated form, allowing it to pass unnoticed. I have no good evidence for this, only the anecdote that in 2001 or 2002 (I don't remember exactly), I had what seemed to be a relatively minor flu-like illness followed by a bout of conjunctivitis. At the time I thought I had two separate illnesses, but I wonder if I didn't have some mild version of the H5N1 or H7N7 flu. Does anyone know if there are specific tests for previous exposure out there?

Dianne: in the course of researching this, I learned (but where?) that while avian flu generally often involves conjunctivitis, H5N1 in particular does not. When I figure out where I read this, I'll update the page accordingly.

Great post, as usual, Hilzoy (and why is it not surprising that you "ace[d] Epidemiology"?) - but I also wonder if extrapolating casualty ratios from the 1918-19 pandemic really is a relevant metric for a theoretical flu outbreak in 2005?
Even given, as you point out, that contemporary improvements in transportation have made the international transmission of infectious diseases far easier (although the Spanish Flu spread handily enough even in the steamship era) - aren't the advances in medical science and technology since then "advanced" enough to cut on the overall death rate?
Or am I missing something (and should go run out and stock up on masks)?

"while avian flu generally often involves conjunctivitis, H5N1 in particular does not."

Drat. Well, maybe I can still hope for partial immunity based on cross-reacting antibodies. (Actually, I'm not at all sure that what I had was influenza at all. It was a lot milder than classic influenza, for one thing...Right, I guess I'm heading to employee health for the flu shot Tuesday.)

Update after looking for confirmation of the symptoms of H5N1: This article states that conjunctivitis can be seen with H5N1, but much less frequently than with other avian flu strains such as H7N7.

One other note from the above article: The article states that in children under 6 the disease is generally self-limited and requires only supportive care except in children given aspirin. Children given aspirin are at particularly high risk of developing Reye's syndrome with this flu. Don't do it.

"while avian flu generally often involves conjunctivitis, H5N1 in particular does not."

Drat. Well, maybe I can still hope for partial immunity based on cross-reacting antibodies. (Actually, I'm not at all sure that what I had was influenza at all. It was a lot milder than classic influenza, for one thing...Right, I guess I'm heading to employee health for the flu shot Tuesday.)

Update after looking for confirmation of the symptoms of H5N1: This article states that conjunctivitis can be seen with H5N1, but much less frequently than with other avian flu strains such as H7N7.

One other note from the above article: The article states that in children under 6 the disease is generally self-limited and requires only supportive care except in children given aspirin. Children given aspirin are at particularly high risk of developing Reye's syndrome with this flu. Don't do it.

"aren't the advances in medical science and technology since then "advanced" enough to cut on the overall death rate?"

Advanced, yes. Enough? We'll see.

Supportive care is much better now than in 1918 and we now have antivirals with some efficacy. Plus we've learned how to make flu vaccines with reasonable efficiency. Unfortnately, it's not at all clear that we have capacity to make enough anti-virals and vaccines if it comes to a pandemic. So go ahead and stock up on masks and gloves. And lots of soap. Soap and water is your friend when it comes to protecting against disease. So is alcohol...er, to put on potentially infected surfaces, not to drink. Drinking it might make you feel better, but wouldn't make you any safer against flu.

I'll try to post this only once, but my computer is acting a little screwy.

JayC: I'm working on -- well, two things, one related to my, um, job, and one followup to this. Basically, though, as far as medical advances: we are working on vaccines. However, it would take months to grow them, there's some question as to whether we're working with the right strain (it's from 2004; the question is how much the virus has mutated since then), and in any case there certainly wouldn't be enough for everyone. Unfortunately, it seems that this virus requires a stronger vaccine than most flus, which makes diluting it less feasible. The one dilution strategy that might work has not yet been tested. It will almost certainly be rationed.

Antivirals: we have only just (like: a few days ago) gotten around to deciding to increase our stockpiles, and are thus in line behind a lot of other countries. Tra la, tra la. We have some, but nowhere near enough. (I gather Canada is doing a much better job.)

Other than that, there isn't a lot of known curative stuff out there. (Although one danger with the flu is getting a secondary infection of some sort, and a lot of those are much more treatable.) People are speculating about whether this or that drug might possibly have some benefit, but as best I can tell, they don't know.

Bottom line (as best I can tell): we're in much better shape as far as secondary infections. Stuff that directly protects from or cures avian flu itself, however, is likely to be in very short supply, and to be strictly rationed.

(And this is without considering the question: should developed countries get the vast majority of medications and vaccines? This isn't just a question of justice; there's also a serious public health argument for trying to nail any outbreak very early. But that would mean using scarce resources that will be needed if this approach fails in other countries, which in all likelihood we won't do.)

Dianne: thanks for the cite. I, too, wish I could hope for immunity.

The biggest other problem is that the main support therapy for serious flu is a respirator, of which there apparently only are about 100,000 in the entire U.S. Any seriously large epidemic is going to cause a major shortage practically instantaneously.

"children under 6"

Does anything special happen around 6?

Plans in the Netherlands stated that with so many people ill you have to recon with a serious disruption of daily life. If 30-50% of the employees in your environment are home, ill, a lot of work cannot be done.

Weird, but I never realized that bit of impact.

They also recommend (in the practical tips section) to use paper tissues for sneezes and throw them away after using them once. If you really want to do all you can you can change the doornobs in your house to once where you do not use your hands to open the door. Doornobs appearantly are viral travel hobs.

dutchmarbel: yes, doorknobs are places where Germs May Lurk. -- Basically, it's worth asking yourself: suppose I were a virus, trying to get from inside one person's body to inside another person's body: how would I do it? (Thus, washing one's hands.)

Yep, but some doorknobs (tnxs, I thought the word looked funny) are touched in area's where you do not really wash your hands. Opening doors in shops, offices, schools, etc.
Before reading all this I never thought of touching a doorknob as an incident that would require hand washing. And I wash a lot of hands, with three little children at home it is the only way to prevent yourself from sneezing 8 months per year...

dutchmarbel: that's why one of the relatively small number of things I plan to do is to actually get some of the alcohol-based towelette thingies. -- And one of the odder parts of taking epidemiology was that it made us all think about all sorts of common things quite differently.

The one that really altered my life was this: apparently, someone analyzed the mints given out in restaurants -- the ones that are not individually wrapped -- and found that -- how to put this? -- every substance normally secreted by humans could be found on those mints.

Ew. I have never eaten one since hearing that.

LOL. I read something similar about peanuts in bars. The little bowls on bars contained on average 7 different kinds of urine --- never EVER will I eat those anymore. Unwrapped sweets will be added to the list now ;)

I thought viruses died quickly once they were no longer surrounded by a human body or by human body effluviants. Wouldn't viruses on doorknobs be dead by the time someone else touched said doorknob?

Does anything special happen around 6?
I'm guessing that it is because the chance of Reyes syndrome increases when aspirin is administered during a viral illness, and since children are more likely to get chickenpox, etc. and their caregivers are more likely to administer aspirin earlier (most adults gut it out until they really feel sick)

Most of those affected (96 percent) took medications containing aspirin on or before the third day of illness. Another study found that children with the syndrome were 35 times more likely to have used aspirin than those who did not take any aspirin (Huritz, 1988; Huritz, et.al., 1987). Due to these findings, people (especially children) with viral illnesses are encouraged not to use aspirin or any medications containing aspirin since it could cause Reye's syndrome.link

I thought viruses died quickly once they were no longer surrounded by a human body or by human body effluviants.

When SARS was a big topic, a lot of stuff was published about lifespan of the virus. This is pulled up google link

The SARS virus can live for up to 15 days outside the human body, Chinese scientists have discovered.

The Key Science and Technology Group under the National Task Force for SARS Control and Prevention Monday revealed that the virus can exist in temperatures of 24 C for five days in patients' saliva, mucus and excrement, 10 days in urine and 15 days in blood.

Obviously, the SARS virus is not the flu virus, but I remember this coming up when my faculty was discussing cancelling student exchanges because of SARS.

CaseyL:

(ot: it's fun to try to figure out the answers to these questions!)

Viruses seem to differ in how long they can survive apart from their hosts' bodies. Alas, however, the WHO says:

"Apart from being highly contagious, avian influenza viruses are readily transmitted from farm to farm by mechanical means, such as by contaminated equipment, vehicles, feed, cages, or clothing. Highly pathogenic viruses can survive for long periods in the environment, especially when temperatures are low."

And, somewhat more specifically:
"The virus can survive, at cool temperatures, in contaminated manure for at least three months. In water, the virus can survive for up to four days at 22 degrees C and more than 30 days at 0 degrees C. For the highly pathogenic form, studies have shown that a single gram of contaminated manure can contain enough virus to infect 1 million birds."

Nothing on doorknobs specifically, however.

I remember someone discussing how artificial sweetners were discovered (maybe McGee in Food and Cooking), which is that experimenters working in a lab went to take a break and found that their lunch or their cigarettes had an overwhelming sweet taste. Now, I know a lot of guys in chem labs can be pretty devil may care, but to think that they got enough on their hands to transfer to the food to have them taste it really makes one realize how easy it is. My daughter is watching Snow White and she's asking the boys if they washed their hands. Yikes.

lj: What's funny about my writing all of this is that I am about as far from obsessively cleanly as it's possible to be.

Well, scratch that, actually: I have known people -- my little brother at age 20, for instance, who literally never cleaned, say, the bathroom sink, so that it got all crusty and peculiar, and odd things started to grow all over it. I've never been like that. But I am a long, long way from being a neat freak.

The problem has already taken Cipro out off the market. My doctor prescribed, but it is no longer available in Texas. A very effective antibiotic for upper respirtory and staph infection. When I went to fill it (manufacture discontinued distribution.
That's really scary.

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