A crash effort to analyze the genes of the swine flu virus has revealed that it first emerged in humans last year — most likely last fall.
"The consistent range we're getting out is the second half of last year — between June and December," says Oliver Pybus of Oxford University. "The best estimate is the middle of that range, kind of September."
That means the newly recognized virus has been hiding in plain sight for the past eight months or so. Researchers say it probably had been circulating in Mexico and causing disease there, but its presence was masked by cases of regular flu and the absence of lab tests to identify the newcomer.
Seeing as how no one noticed a statistically significant rise in flu deaths last flu season I'm going to go out on a limb and say that this "new" virus isn't any more menacing than the old ones. Of course those who fanned the flames of hysteria over this have to say things like,
"We're going to be actively monitoring what it does as it moves through the population," says Joan Nichols. "As it turns around and comes back to us in the fall, we'll know much more about it."
If it starts causing severe and fatal disease at a high rate in the Southern Hemisphere, that will be obvious enough. Scientists will quickly analyze viruses from such cases to see if they can identify the genetic changes that correlate with increase virulence.
But unfortunately, the absence of such an obvious signal this summer may not mean the virus won't evolve into a pandemic killer in the fall. That's because researchers know relatively little about the genes that confer virulence.
I'm wondering why it took so long for someone to ask this question, Why So Many Swine Flu Deaths In Mexico? Shouldn't that have been the first question to ask, along with the question of whether the deaths were statistically significant, before panicking the world? And given that the virus has been circulating since last fall shouldn't we also be asking why it wasn't noticed until April of this year (aside from the fact that symptoms are indistinguishable from those of regular flu)?
There is a saying that a lie can run 'round the world while the truth is still getting its boots. Well here comes a bit of truth and reasoning.
Deaths In Early Virus Outbreaks Can Be Misleading
The first reports about swine flu in Mexico made the disease sound highly lethal. But now, public health officials are saying the new H1N1 strain may be no more deadly than plain old seasonal flu.
With swine flu, as with SARS and West Nile, the first identified cases in Mexico were people in hospitals who'd become very ill.
Initially, health officials had detected a surprising number of otherwise healthy young people hospitalized with pneumonia. Many of them died. And the first tests for swine flu were done in this group.
That made sense, says Dr. Frederick Hayden, a flu expert at the University of Virginia, but was bound to make the virus look more dangerous than it actually is.
"The hospitalized patients really represent only a fraction of all those affected," he says.
And mild cases of swine flu could have gone undetected for weeks, Hayden says. But this time, flu experts got a break. They found out that the virus had infected dozens of students from a high school in New York after some of them had visited Mexico.
A Week after I started the first draft of this post people are still doing a Chicken Little dance over swine flu. W.H.O. May Raise Alert Level as Swine Flu Cases Leap in Japan.
Now seems to be a good time to book a trip to Mexico since everybody else is staying away out of irrational fear of the flu.