Wednesday, April 29, 2009

The Mexican Flu and the Weather

Many of you know that I am a weather forecaster in the Air Force. I do this primarily for the Army as part of a Combat Weather Team. The Army doesn't have its own weather forecasters, the Air Force does it for them. Where our Army customer goes, we go. Thus the "combat" prefix. We carry weapons and temperature gauges but I've always said that if the weather guy is firing his weapon at the enemy then its really not a question of whether you're going to win or lose that battle but rather just how bad the loss will be. But I digress...

So what does this have to do with the Mexican Flu? Well, nothing. But there are a number of occasions where an analogy might be made, the latest being Hurricane Ike, which hit Texas this year.

Ever since Katrina the State of Texas begins to get spun up whenever a tropical system approaches the Gulf. Usually, long before. It is somewhat a source of amusement for us in the weather business as many things can happen that far out. But after Katrina/Rita (aka "Katrita") the State takes no chances and begins preparations far in advance.

On one hand this makes good sense. On the other many people point to the false alarms and begin to not take the words of warning seriously.

As Ike approached the Texas coast the models seemed to indicate that the trajectory might affect Austin (a couple of hundred miles inland). You may laugh but there is historical precedence for hurricane effects to be felt in Austin and they included tornadoes, high winds, and flooding.

When warnings are given there are typically three types of response. First, there are those who, without filtering the hysterical TV headlines (designed not so much for information as for ratings) rush out a week in advance (a lifetime in weather terms since so much can change) and start stocking supplies, generators and boarding up the windows. The second response is from those who say, we've heard this before and nothing has come from it and this will be the same. (when this group is on the coast, they make up the large portion of 9-1-1 calls in the midst of the storm seeking a rescue that cannot be made) The third group, hears the warnings and begins to pay closer attention to news and weather and makes prudent preparations as the storm gets closer.

It occurs to me that much the same thing is happening with the Mexican Flu outbreak. There are those who rightfully point to the the shrill TV anchors and the "All Flu, All the Time" mentality and say its vastly overblown. The virus is so far mild in the US and no fatalities have been reported except for the toddler who came from Mexico. They point to the African diseases that kill many more and the alcohol related deaths and even the thousands that die from "regular" flu every year in this country. And they have a point.

But while I will agree that there is a danger in over reacting and blowing the situation out of proportion, the opposite error is perhaps even more dangerous.

Because the danger here is not necessarily a short term threat. It may be. It may fizzle out in a few weeks and never be heard from again. but it also may not. Or it may fizzle out and then reappear in the Fall in an even more virulent form.

The concern (among others) is that the public begins to think that the whole thing is being hyped:

With the H1N1 swine flu virus, the world appears — at least for now — to face a much less fearsome foe. That fact leads to some relief and some concern. The concern is that people may not be taking the threat of a pandemic seriously enough.

“I think that people misunderstand the word pandemic,” Thompson said from Geneva. “Pandemic speaks to the geographical distribution of disease. That it’s widespread, that it’s global.”

“Then there’s the question of severity. How severe is that disease? And we can have very mild pandemics. But we can also have pandemics that can come in waves.”

“And a first wave might be mild. And that might lull people into complacency thinking — `we’ve seen this, it’s not so difficult to deal with, it’s not so scary.’ And then another wave comes along. That has been a pattern. And that’s something we have to keep thinking about.”
Officials have started to point to the example of the 1918 Spanish Flu, the worst infectious disease outbreak in known history. It’s estimated upwards of 50 million people around the globe succumbed in that pandemic, which was caused by an H1N1 virus believed to be of avian origin.

The professionals over at Effect Measure are a great place to go for info. The Editors of Effect Measure are senior public health scientists and practitioners.

If there is normally so much respiratory disease around, why is this an outbreak or even an epidemic? It's a more difficult question than it appears, and it relates to "what did you expect?" An epidemic is an increase in the number of new cases beyond what you would expect. Four or five cases of human rabies in an area in the US would be an outbreak or even an epidemic. Hundreds of colds or even serious pneumonias in an urban area is normal. It's not an epidemic. What makes the swine flu an outbreak is that it is an infection with a virus we haven't seen before and which we believe may be new. Hence these cases are not what we expect and it is an outbreak.

The thing is there is much we do not know:

Another thing that most people and probably most clinicians expect is that we know a lot about influenza. Perhaps because of the increased scientific interest since bird flu (an increased interest which will pay off handsomely in this outbreak, by the way) we do know quite a bit, but we also now know many of the things we thought we knew about flu, like the main ways it is transmitted from person to person, we don't really know. For example, how likely is it that you can get flu by touching a door knob or arm rest that someone with the flu just touched? Or that you can get the flu by sitting in the same emergency department waiting room (but not next to) other flu cases? These are open questions (see some of our many posts on this here, here, here, here). Why is flu seasonal? We don't know. ...

...the influenza virus is highly unpredictable and our certain knowledge of it very scant. If you've seen one flu pandemic, you've seen one flu pandemic.
If this outbreak becomes a sustained worldwide one -- the definition of a pandemic -- you should not expect it to be the same as any other pandemic. It might be like 1918, 1957, 1968 or just a bad flu season. Or not. (Effect Measure)

Wash your hands, cover your mouth when you sneeze/cough, stay home if you're sick and stay informed.

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