Map of life expectancy at birth from Global Education Project.

Monday, April 27, 2009

Flu Schmlu

Yes, it is prudent to assume that someday, somehow, an emerging infectious disease pandemic will cause major global problems. I've said it a million times. However, contrary to the famous motto of Faber College, it is not always the case that Knowledge is Good, if it leads people to do stupid stuff.

Influenza is a common disease and a continual pain in the parts. The virus reproduces very sloppily so new strains keep emerging, which means we don't get the lifelong immunity we do from bouts with most viral diseases, which means that we can keep getting the flu year after year. Fortunately, for the vast majority of us, the vast majority of years, that means nothing worse than a few days off from work or school feeling like crap. (I highly recommend ginger tea.) It's a bummer, but that's the human condition.

We hear that something called "influenza/pneumonia" is the cause of about 63,000 deaths in the U.S. each year -- 10% of the number attributed to heart disease -- but that's highly misleading. (The reason they lump them together is that most of the time, it isn't clear whether people had the flu or not. Some of the people who die of respiratory infections did, but we don't generally have laboratory confirmation. People who are said to die of "influenza" for the most part die of bacterial pneumonia secondary to influenza or a different viral infection that appears similar.) The vast majority of these people are already sick and debilitated; many have advanced dementia and death from pneumonia is a mercy. Tragically, a small number of children also die each year from ordinary seasonal influenza. It would be nice to be able to stop that from happening but it's nothing new or different or strange.

Every once in a while a strain of influenza emerges that for reasons which are not well understood causes more severe disease than usual and/or spreads more easily and so causes unusually widespread disease. In 1918, the virus was unusually dangerous to otherwise healthy young men, less so to older folks. The hypothesis is that an overaggressive immune response explains this.

Okay, so what's going on right now? Probably absolutely nothing out of the ordinary. We're at the tail end of the flu season right now, and it happens to be that at this time a new strain of flu has been detected. The Mexican authorities seem to think it can cause unusually severe disease, but that has not been observed elsewhere and it is not clear whether that is really true in Mexico City either. When a small number of young men in Mexico City suddenly die of pneumonia, my first thought is HIV, not pandemic flu. (And it is a small number. The Mexican authorities have attributed 100 deaths to this virus, of which only 18 have been confirmed as actual swine flu infections. 20 million people live in Mexico City.) Influenza normally cannot survive in warm temperatures, which is why flu season ends in the spring. Unless this virus has some as yet completely unknown properties for which there is no evidence whatsoever, this outbreak is almost certainly going to die out on its own in no more than a couple of weeks. Even if it does not, there is no particular reason to think it will ever be much more than an annoyance.

Unless, of course, we proactively make sure that it is more than that. Which is exactly what is happening. I am not going to accuse the Mexican authorities of overreacting because I don't have the information they do, they have difficult judgments to make, so they did what they did. Undoubtedly, however, they have imposed a huge economic cost on the country, with the political and economic capital completely shut down, tourism effectively suspended, and small businesses without customers.

Here in the U.S., the TV is wall-to-wall flu, with the hair hats screaming and yelling about 40 cases of swine flu in the U.S. -- every one of which has so far resulted in perfectly normal, mild, self-limiting illness. The Secretary of Homeland Security, no less, has held a press conference on national television to declare a Public Health Emergency. How do you expect people to interpret that? Of course it's upsetting and I'm sure people with the sniffles will be clogging emergency departments in the days to come. (I hope not, but I'll be surprised if it doesn't happen.)

Here's what they should have done. Have the Acting Director of CDC issue a statement to the effect that measures are being taken to permit the rapid transfer of supplies to places where they are needed, should that occur. Reassure everyone that local public health authorities are vigilant about surveillance and that we'll have information for the public as soon as there is any that they need to have. Right now, however, all you need to know is what you should always keep in mind: wash your hands regularly, cough into your sleeve, stay home if you're sick, and see a doctor right away if you have a high fever or trouble breathing. Meanwhile, as far as we know right now, there is nothing to be concerned about. Carry on.

And the newspapers should put it on page 15, and the TV news should do 1 minute in the middle of the broadcast. The Huffington Post should get a life. If things change, I won't regret what I just wrote, because it will still be correct.


kathy a. said...

the huffington post is quick to jump on news and offer tons of links, but i often think they shouldn't indulge in any more headlines over 24 point font. and certainly not in red. [no, i don't favor censorship, but there is such a thing as too much, too often.]

it will be interesting to find out why there have been so many severe cases in mexico city and not elsewhere. it certainly seems plausible that the cases where folks have died also involve pre-existing illness, but i haven't seen anything addressing that yet.

isn't part of the concern that this is "swine" flu, with bird and human factors thrown in? so nobody has immunity, and unlike a lot of non-human flu strains, this one seems to spread with human contact, too? that seems to add a level of unpredictability to the mix.

i'm encouraged that the primary public health measures urged by you and the CDC are just ordinary ones -- wash your hands, don't go spreading your germs if you are sick.

Cervantes said...

The novelty of the strain is actually not clear. All flu strains are new, which is why the vaccines from last year doesn't work well this year. That's not the issue. The issue is whether the hemaglutinin or neuraminidase proteins in the viral envelope are sufficiently novel that the immune system has major trouble with one of them. Just because this is a new swine flu doesn't necessarily imply that -- and understanding of the issue is not deep enough to predict it from the sequencing. We just have to wait and see. So far, seemingly, so good.

whisker said...

Thanks for the enlightening post Cervantes.

robin andrea said...

I typically don't let this type of news-generated hysteria bother me. But after spending several hours in an Urgent Care clinic in a very populated city yesterday, I suddenly felt very vulnerable. Hanging out with the masses is quite an experience, under the best of circumstances. But yesterday, every sickly cough, and all those cranky-runny-nosed children made me just a bit nervous. That said, I wish the news people would do their jobs, which is to inform. It is not to stir passions or fear.

roger said...

thanks for the calm assessment of the flu situation. (robin andrea and i took my mom to urgent care for x-rays for a possibly cracked rib. it only took 3 hours. a woman with medicare and every supplemental possible couldn't get an appointment with her primary care doctor for another week. but socialized medicine is evil) several people in the urgent care waiting room were wearing breathing masks and most were also using the hand sanitizer repeatedly. there was a sign on the entry asking those with flu symptoms to go to the side door.

my brother who lives in mexico is flying here next week. we told him not to bring any flu.

kathy a. said...

oh, roger -- she couldn't see her own doctor for a WEEK? holy cow.

part of the wall-to-wall flu coverage is now about the over-the-top wall-to-wall coverage. i suppose that is a step in the right direction, even as it borders on the ridiculous?

Cervantes said...

Yes folks, I basically have two and a half concerns about this. The first is the economic damage that is already being done, not by the flu, but by the panic. The harm to the travel industry worldwide is obvious. If people and authorities continue to react excessively and prematurely, we'll end up doing significant damage not only in the short run, but in the longer run because people won't believe the alarms on the upcoming occasion when they are legitimate.

That equals 2. The extra 1/2 is that something of a corollary, although it's just as important, and that is that all this attention distorts people's perceptions of the nature of the public health problems that we face. We're all in a lather over the possibility of an epidemic that, even given the absolutely worst case scenario, will be over in a year and might cause something like a few tens of thousands of deaths and millions of miserable weeks slurping chicken soup.

Meanwhile, we have tobacco killing 400,000 people in this country alone every year, 4 million little kids dying every year from easily preventable common infections and malnutrition, a devastating epidemic of obesity causing people to die horrible, lingering deaths from diabetes and heart failure, unconscionable social inequality leading to ubiquitous disparities in health status and longevity . . .

And so on and so forth. All of which the media, and for that matter the CDC, largely ignore.

Anonymous said...

Cervantes- I'd say your 'worst case scenario' estimate of deaths is off by a few orders of magnitude. The 1918 Spanish flu epidemic killed an estimated 50 million people worldwide--more than died in WWI--not quite a normal flu season.

Granted, there is definitely not enough information right now to know if this strain could prove as deadly, but the unpredictable nature of the flu is precisely why public health experts are taking it so seriously. (Note, we have much better tools to track and treat flu today than existed then).

But I'd suggest reading up on the 1918 Spanish flu epidemic for some background. The 1918 flu started out in the spring as a mild outbreak and came back as a deadly in the fall.

Cervantes said...

Listen anonymous, you don't have to give me any history lessons -- I will be very surprised if I don't know more about the 1918 flu epidemic than you do. This has no, repeat no possibility of being anything like that, for various reasons. I may have to do another top level post to explain why.