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The Hunt For Pig Zero

[My story in today's paper. I'll post some additional material on this topic -- outtakes -- later today.]

Somewhere out there, somewhere along the way, a single creature got all this started. A pig, presumably. Pig Zero.

Scientists suspect that two influenza viruses common in swine, one rooted in Eurasia and the other in North America, came together in a single cell within a pig. The two viruses exchanged their genes like a couple of kids swapping school clothes. The result was a novel strain of virus, with, according to scientists, two genes from the Eurasian virus and six genes from the North American virus.

The new strain then jumped to humans. Where is unknown. Mexico is a possibility, but so far the virus hasn't been found in any Mexican swine.

All of this is the latest iteration of a phenomenon dating to the dawn of mankind: zoonosis. A zoonotic disease is one that spreads from animals to humans, or vice versa. Bubonic plague came from a bacterium that infects rats and can spread via fleas to humans. HIV is a virus that passed into people from a monkey. Malaria, tuberculosis, rabies, yellow fever and typhoid fever are zoonotic.

And it's a two-way street, as seen recently when a Canadian farmworker infected with the new H1N1 swine flu apparently passed the disease to a herd of pigs. When it comes to influenza, the thoroughfare between Homo sapiens and Sus scrofa -- domesticated pigs -- is something of a superhighway.

From the perspective of an influenza virus, the receptors on the lungs of a human being -- the places where the little spiky knobs on the virus can attach themselves -- look very much like the receptors in a pig. A pig's anatomy is so similar in certain respects to a human being's that pig heart valves are routinely transplanted into human heart patients.

"Zoonotic agents don't care whether it's a human or an animal ," said Juergen Richt, a professor of veterinary medicine at Kansas State University.

Increased Crowding

Thanks to vaccines and antibiotics, the war against infectious diseases seemed to be nearly won by the second half of the 20th century, but the pathogens have shown themselves to be resilient and adaptive. Meanwhile, the human population has grown to more than 6 billion, sustained by billions of farm animals, many raised in close quarters on factory farms, said JoLynn Montgomery, an epidemiologist at the University of Michigan.

"There's more crowding in animals, and more crowding in people, and the crowding is merging," she said. "People are getting diseases from animals more frequently. I'm not sure the diseases themselves are getting worse." Public health measures -- careful surveillance of zoonotic diseases -- can counterattack the problem, she said.

Zoonotic diseases can also come from wild animals, and new pathogens can emerge as human beings penetrate remote, isolated regions of the planet, said Thomas J. Inzana, a bacteriologist at Virginia Tech. Some exotic pathogens are so "hot" that they can't spread as easily as viruses that are less lethal, he noted: "It doesn't do the pathogen any good to kill its host."

Which is why flu is such a problem: It has essentially co-evolved with people, pigs, birds and other animals. And it's malleable. Influenza is what is known as an RNA virus. Such viruses, mere snippets of genetic material, replicate inexactly, like photocopy machines on the fritz. That sloppiness enables them to evolve rapidly and find new hosts, and makes them a moving target for vaccine makers.

The specific origin of the new flu strain remains a matter of intense investigation. Even the presumption of a Pig Zero is just educated guesswork. The new virus conceivably could have spliced itself together inside a human being or some kind of bird. A pig is the most likely source simply because two ancestral viruses had clear genetic markers of swine-related flu, and a pig is the most likely place for two swine flus to converge, said Andrew Pekosz, a virologist at the Johns Hopkins Bloomberg School of Public Health.

Click here to keep reading.

By Joel Achenbach  |  May 7, 2009; 9:16 AM ET
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Next: Swine Flu Is Not Done With Us Yet


There should be a Pulitzer for explaining things. Thanks JA.

Posted by: frostbitten1 | May 7, 2009 9:24 AM | Report abuse

I agree, frosti.


No ill effects, Raysmom.

I saw that Hornaday review too, 'Mudge. Wow! :-)

Posted by: Scottynuke | May 7, 2009 9:30 AM | Report abuse

Not to encourage digressiveness or anything -- digression -- digressivity -- but I have a query. I was just now on my back porch, trying to strategerize about planting tomatoes, thinking that maybe I should take advantage of all this rain to get stuff in the ground. But here in Washington in my experience the tomatoes just dont grow hardly a bit this early in the season. I always plant May 10. That's THE tomato date here. So...jump the gun or wait?

Posted by: joelache | May 7, 2009 9:34 AM | Report abuse

Recently, a story in New Scientist suggested that pig virus researchers and their human-virus counterparts didn't seem to communicate as much as they should, unlike the viruses themselves.

Posted by: DaveoftheCoonties | May 7, 2009 9:35 AM | Report abuse

In Philly we're about 1.5 weeks behind you and I'm waiting another week.

Posted by: -dbG- | May 7, 2009 9:35 AM | Report abuse

Very nicely done Joel! As in all good science reporting you know just what to keep in, and just as importantly, just what to leave out.

The notion that viruses are fast evolving critters is key to understanding the dangers of overusing anti-viral drugs as a "preventative." I know that the CDC claims that overuse of Tamiflu has dramatically increased the resistance of seasonal flu to this drug.

Also, I wanted to point out that "Sus scrofa" is really fun to say.

Posted by: RD_Padouk | May 7, 2009 9:38 AM | Report abuse

Ummmmmm... Three days' difference, JA? Go crazy, plant now.

Posted by: Scottynuke | May 7, 2009 9:38 AM | Report abuse

Raysmom, we'd believe it wasn't you if a post using your nom-de-Boodle said "Raysdad" or another nom-de-Boodle at the end of the post.

Or, you could trying logging out, he could create a n-d-B, clear the cache and log in. Then either of you might have to clear the cache often in order to log in.

Posted by: -dbG- | May 7, 2009 9:38 AM | Report abuse

Joel, if you want to get all sciency about it, check the NOAA web site for your area and find out how many growing degree ddays you've had, then check the long range weather forecast. Spring iws well past sprung in your neck of the woods, so I wouldn't expect any late season, Day After Tomorrow whiteouts. Try planting some of your tomatoes upside down in buckets. It worked for my wife's aunt in Ga. Then consider throwing all caution to the wind, and plant you tomatoes today. You have nothing to lose but your tomatoes. Be aware that anything I plant usually dies within a fortnight.

Posted by: -jack- | May 7, 2009 9:43 AM | Report abuse

I could not find this article in the dead trees edition this morning. I hope Joel got paid for it anyways.

Posted by: yellojkt | May 7, 2009 9:44 AM | Report abuse

That's a topic of much fevered analysis, Joel. I used to traditionally plant right after Mother's Day, but it seemed like the 'maters did nothing but provide varmint food.

My personal solution is to wait until closer to the end of May and then use the largest plants I can find.

Granted, this is kind of cheating.

Posted by: RD_Padouk | May 7, 2009 9:45 AM | Report abuse

As I pointed out to Joel last night, his article doesn't mention vectors/ intermediate hosts. And isn't it questionable whether microbes or bacteria are animals--in his list of zoonotic diseases. *l* And shouldn't mosquito vectors be mentioned--especially those who bite deer and monkeys?

(Full disclosure--my roommate in collge--the year I spent in the dorms--was a zoo (pronounced like "low") major. Hardly means that I spent last night at the Holiday Inn, however.)

Posted by: laloomis | May 7, 2009 9:47 AM | Report abuse

Doesn't Scrofa play for the Houston Rockets?

Posted by: Scottynuke | May 7, 2009 9:47 AM | Report abuse

From last kit-- a couple shoutouts--

The Dawn patrol made my morning, with Rainforest's wire poem and that visual of Scottynuke finding out he's more androgynous than he ever dreamed of being.

And RD, for sending his thoughts where no man has gone before.

Posted by: Wilbrod_Gnome | May 7, 2009 9:53 AM | Report abuse

I plant tomatoes right after the frost-free date of May 21 in our area. For the peppers and eggplant I wait for the 'settled' weather date of June 4-6. Peppers don't like cool nights at all, that may prevent them from flowering at all.

So if there is no cold weather forecasted for the next few days go crazy with the planting.

Posted by: shrieking_denizen | May 7, 2009 9:53 AM | Report abuse

Planted my six tamater plants 3 weeks ago, Joel. They're shooting up like crazy. Ditto the sweet onions and the snap bean plants. Holding off a bit on the lettuce, though. Carrots are in, but more reluctant than the onions. Gonna plant a second round of onions on Saturday. Our raised garden is filling up fast.

Scotty, IIRC Scrofa was from either South Philly (around 19th and Jackson) or South Jersey (Millville-Vineland?), and played bass guitar behind Bobby Rydell. Died of multiple self-inflicted gunshot wounds to the back of the head in a parking lot outside a Cherry Hill all-you-can-eat buffet house with a wad of betting slips in his mouth. Very sad.

Posted by: curmudgeon-1 | May 7, 2009 10:00 AM | Report abuse

Joel, thanks for the reminder why pigs are so close to my heart (Trying not to sing the Homer Simpson "Spiderpig" song to myself here, and apologies for the tune cootie I may have set off for some of you. And by "you" I mean Scottynuke.).

Who knows if the researchers will ever find PZero or if it's even still alive. There may be nothing left of PZero but a pile of rib bones, a couple of bags of fried rinds in a vending machine and maybe a couple of footballs.

For the record, I still love scrapple. Even if it's a little - you know - cannibalistic?

For some reason, I see the word 'zoonosis' and render it in my brain as 'zoognosis.' Apparrently my mind has an intersection between pathology and spirituality - a type of pathologic, perhaps?

Trying not to consider the idea that being the Jackson Pollock of the English Language is a sickness. But it would explain a few things.

Maybe it was something I ate.


Posted by: -bc- | May 7, 2009 10:06 AM | Report abuse

I bought my tomatoes and peppers in early March and kept them in the sunroom till Easter. They've been in the ground now for a couple of weeks. After the rain of the last couple of days (yay!), the Roma is perking up. The Early Girl is growing gangbusters.

My pole beans are popping out of the ground this morning, and the moonflowers have germinated. The sage looks contented, the zinnias and bells of Ireland have a couple of little leaves. No anemones yet, they probably won't grow. But several coneflower seeds that I planted two years ago have germinated! Those seed were overrun by nicotiana last season and the one before.

Joel...go for it!

Posted by: slyness | May 7, 2009 10:06 AM | Report abuse

Splendid and concise explanation, Joel. With wit and simple language you included teh basics, without drifting into more complex tangents. Just as most of us walk before we run, most of us need the essentials explained before speculating about details.

I only wish I had advice for you about tomato planting. Everything here is pure green jungle, so I'm no doubt late in my planting, and it doesn't look like I can do anything before the weekend is over (there is a weekend soon, isn't there?).

I am very interested in this whole upside-down tomato concept, and want to try it. Usually half my tomato plants die and the other half produce, collectively, one tomato, so I'm pretty open to suggestion. I do have a question, though: how do it work? don't the plants fall out?

Posted by: Ivansmom | May 7, 2009 10:07 AM | Report abuse

Meant to add that I've been considering the idea of getting some tomatoes planted too.

Which is probably a good reason for not doing so, as I've typically been an excellent example of what *not* to do in almost any situation.


Posted by: -bc- | May 7, 2009 10:08 AM | Report abuse

Lewis Grizzard, the late Southern humorist (think Gene Weingarten with a drawl), had a pig valve put in his heart way back in the 1980s. He often used the situation to humorously explain his frequently swinish behavior. Much of which predated the actual pig heart valve.

Posted by: yellojkt | May 7, 2009 10:11 AM | Report abuse

Hey, byoolin, where ya been lately? And anybody seen Boko???

Posted by: curmudgeon-1 | May 7, 2009 10:17 AM | Report abuse

yello, A6 in the dead trees edition--read it on my way in this morning. Joel, this is a fine piece of writing--concise, simple language and of a very consumable length (kept so by not going off on various tangents that some may wish to see).

As for 'maters, I think the danger of frost has passed. The worst that will happen is that they won't grow much until the soil warms up more. To keep bunnies away, plant some marigolds around the perimeter of your garden.

Posted by: Raysmom | May 7, 2009 10:17 AM | Report abuse

bc, I was humming "Spider Pig" before I finished reading the headline. Some things are too perfect.

Posted by: Ivansmom | May 7, 2009 10:18 AM | Report abuse

I think the tomatoes are sensitive to soil temperature. Some people put black plastic on the soil to get a head start. Also there's a lot of thermal energy in a spring rain that can warm the soil. So I'd say take advantage of rain, or at least recent rain.

Posted by: Jumper1 | May 7, 2009 10:18 AM | Report abuse

So no basis to the rumour that the initial rendezvous between the viruses was arranged in vitro by a flu vaccine company with the blessing of the marketing department?

Posted by: kristopher1 | May 7, 2009 10:20 AM | Report abuse

Sounds more like the viruses were speed-dating.

Posted by: Raysmom | May 7, 2009 10:23 AM | Report abuse

I've finished refreshing my coffee and reviewing my notes from the pandemic subcommittee meeting yesterday on the Hill. I see that I must have been listening more during this portion of the hearing, rather than taking notes, but here's the gist of it.

World health officials are most concerned about the spread of the latest swine flu to Africa, where many countries experience extreme poverty and there would be great difficulty in both tracking and reporting of swine flu cases. It's important to point out that much of Africa lies below the Equator, which puts the majority of the continent in the Southern Hemisphere, where fall is getting started.

In its reporting yesterday, Bazell and MSNBC--IIRC, had footage of Dr. William Schaffner, a flu expert at Vanderbilt University (clinical trials for a new smallpox vaccine were conducted at Vanderbilt a handful of years ago) said that despite the weather warming up here [in the Northern Hemisphere], the swine flu is still spreading (which is rather atypical, indicating we really don't know how this new flu strain will "behave" yet.)

How should world health officials expect to possibly distribute testing kits for swine flu to counties in Africa, especially when clinics, particularly the rural ones, lack most of even the most basic medical supplies?

One of the concerns for African, as well as others parts of the world, in those countries without much of a centralized government and almost nonexistent health care systems. Think as well of the challenges of coordinating communication and distribution of medical supplies and equipment with dictatorships, this form of governing mentioned during yesterday's hearing on pandemics.

According to Dr. Dennis Carroll, special advisor on pandemics to the U.S. Agency for International Development, both Paris and UN partners are addressing both refugee populations and migratory populations. It's important to remember that there are still clusters of hunter-gatherers scattered across the globe. Many don't have access to cars or Costco.

The refugee populations are those from war-torn areas. One need only think of several countries in Africa with large numbers of refugees--and secondarily the Middle East, whose health is marginalized because of the disruption of their lives and removal from their farms, this upheaval often meaning that their health is compromised because of lack of food and water, basic goods and services, and semi-starvation.


Posted by: laloomis | May 7, 2009 10:27 AM | Report abuse

kristopher, that's pretty sick, as well as illogical. Assuming the premise, the vaccine wouldn't be available for six months to a year after the initial outbreak, i.e. way past the time it was needed and would sell like crazy. Releasing said vaccine "in time," on the other hand, draws attention to itself and raises the very question, how did they know in order to make it?

Posted by: curmudgeon-1 | May 7, 2009 10:28 AM | Report abuse

The latest example of a large movement of people, of refugees, is occurring this week in Pakistan, where thousands are fleeing the Swat Valley and Buner region as the Pakistani military moves in to combat the Taliban.

The latest about thousands of Pakistani refugees, with a useful map:

According to CDC's Dr. and Rear Admiral Anne Schuchat, the CDC has "an interface" (whatever that means--more bureaucratese-speak) with Russia, which has a "center" in Khazikstan, but the CDC isn't working through this center, but rather bilaterally with Russia. (whatever that means). I believe Schuchat said the CDC either has offices in or has liaisons with Rome, Ho Chi Minh City in Vietnam, and Johannesburg (formerly Pretoria, since it was mentioned yesterday) in South Africa.

It seems that worldwide health officials are aware of all the issues of a potential worldwide health pandemic, including the critical issues of the possible spread of swine flu in developing and poor countries and populations on the move--whatever the underlying reason or cause, but can they stay on top of the virus?

Posted by: laloomis | May 7, 2009 10:31 AM | Report abuse

And anyway, way too many people inside said company would be in on the secret, and it would leak out sooner or later.

There are two vast differences between this scenario and the scenario of computer viruses. (a) Computer viruses don't kill people, and (b) a computer virus can be created and dispersed by a single person acting alone. It's not the same thing as an entire laboratory (in collusion with a marketing department) creating a bio virus.

Posted by: curmudgeon-1 | May 7, 2009 10:33 AM | Report abuse

No kris. NPR had a piece this morning on the origin of the virus. The great-great-grandaddy of this virus was the result of hitting the viral trifecta: mixing, mutation and reassembly of human, avian and swine viruses, prresumably on the pigs' skin. The human viral components allowed it to jump from the hogs back to humans. This occured, by the best estimates gleaned from mutation rates, some 20 years ago. More mutations, mixing and reassembly gave rise to the current virus in Mexico, again by the best estimates in sometime around September of last year. The outbreak was difficult to detect because it was masked by fatalities from the normal ful season last year, and when that cycle was over, fatalities from the continuing cycle of infections from the new virus escalated to the point where it progressed through phases 2, 3, and 4 of the WHO pandemic alert rating system. Now, amid much controversy, people are floating the idea of having swine flu parties in order to build natural immunity in the interim, until a vaccine is developed. Think chicken pox parties.

Posted by: -jack- | May 7, 2009 10:38 AM | Report abuse

Jumper, many gardening supplies company sell red plastic sheet to lay around tomatoe plants. I have no idea if it works or not.

Posted by: shrieking_denizen | May 7, 2009 10:39 AM | Report abuse

This guest op-ed at the NYT today by Nathan Wolfe, the director of the Global Viral Forecasting Initiative and a visting professor of human biology at Stanford, complements today's entire discussion:

Two relevant grafs near the end of his editorial:

My organization and its collaborators have recently set up virus monitoring stations in China, Laos, Madagascar, Malaysia and the Democratic Republic of Congo. Yet this is just a beginning. To establish a worldwide safety net, we would need to monitor thousands of people exposed to animals in dozens of sites around the world — not only hunters but also people working on farms and in animal markets. It is important that the American government make pandemic prevention a priority and devote more resources to expanding disease surveillance in people and in wild and domestic animal populations throughout the world.

Our current global public health strategies are reminiscent of cardiology in the 1950s — when doctors focused solely on responding to heart attacks and ignored the whole idea of prevention.

Posted by: laloomis | May 7, 2009 10:45 AM | Report abuse

It just goes to show how far paranoia can go when the Bushies threw the world into a nightmare. And post anthrax, the Cipro sales given at one point as possible motive, and the whole clan's investment in pharmaceuticals. Exercise some imagination and you can scare yourself silly.

I was reminded recently that they were raising hell about the International Criminal Court BEFORE 9-11. Apparently some people wanted Henry the K's head. In fact, there was a suit filed for damages against his involvement in some skulduggery leading to some political murders. Filed on, I believe, Sept. 10 2001. Wonder what became of that suit... off to google I go.

This is the biggest city I ever lived in, and I've lived here now over 20 years. It was a pleasant surprise when I started meeting people and finding out we had mutual friends, a rarity up to then. The internet is getting that way. I just ran into byoolin on a totally different site.

Posted by: Jumper1 | May 7, 2009 10:50 AM | Report abuse

hi, joel. great reporting on the swine flu.

i have a question though about zoonotic (great word) flus -
is there really a difference between how easily a human can catch swine flu versus avian flu?

i thought all these zoonotic flus were analogous in the sense that humans might catch them directly from an animal, but it a took genetic mutation for humans to be able to spread zoonotic flus to other humans. one of the comments in the article made it sound like we don't catch avian flus, but i thought sars and the 1918 pandemic were both avian flus that had this genetic mutation. or are we more susceptible to viruses from particular animals?

just curious. (maybe i didn't understand something.)

Posted by: LALurker | May 7, 2009 11:01 AM | Report abuse

Did you two exchange the Boodle Secret Handshake(tm), Jumper?

Posted by: Scottynuke | May 7, 2009 11:03 AM | Report abuse

I do think kris is onto a perfectly good plot for an upcoming James Bond movie. It would require an evil supervillain, a secret underground lair (preferably in a volcano, all the better to keep the virus 'hot'), and an extremely beautiful immunologist prone to nude sunbathing.

Posted by: yellojkt | May 7, 2009 11:07 AM | Report abuse

Dr. Zoey Notic.

Posted by: curmudgeon-1 | May 7, 2009 11:18 AM | Report abuse


Will there be monorails?

Posted by: russianthistle | May 7, 2009 11:21 AM | Report abuse

With Hugh Jackman as the the new Bond!

Posted by: Jumper1 | May 7, 2009 11:25 AM | Report abuse

I started an bunch of differnrt seeds indoors in little peat pots by the south side window near the computer so I’m sure to check them out everyday. Only problen I didn’t label the pots. So now I have tiny zinnias, marigold, early girl tomato and costoluto genovese tomato plants growning nicly that all look alike. I started two differnet batchs three weeks apart but they all look the same. I guess I will have to wait a few more weeks before putting them out so I know which is which. The only identifiable seedlings are the giant sunflowers. The problem with them is they are so leggy I have to add a support to keep them upright. The snap peas and radishs planted outdoors were up in a week and are doing well in spite of some frosty mornings. Two hills of zucchini haven’t made a showing in over two weeks. Maybe because we got a rescue three year old 80 pound airedale a couple days after planting and he and the welsh terrier pupply got quite rambunectious upon gretting and trampled through that raised bed. Maybe they put the seeds down too deep. Oh well easy to plant some more. One head of garlic began to sprout in the kitchen so we just pulled the cloves apart and stuck them in the ground around the rose bushes and they are growing nicely.
I bought a nice looking tomato plant at Fred Meyers last month and was doing good indoors and I started putting it out everyday to harden and give it some sun. The one day I didn't check the weather report I missed a frost warning and its head got bit. But it seems to be recovering.

Posted by: bh72 | May 7, 2009 11:28 AM | Report abuse

How do we create a new strain?
Unleash on the world a new cold? (so cold)
Maybe it's not too demanding
Maybe we just orgy with others (be bold)
Maybe we'll merge with each other
Sex 'til we're satisfied (diversified)
Why don't we go infect another?
This is what it sounds like
When pigs fly

Posted by: DNA_Girl | May 7, 2009 11:30 AM | Report abuse

Just one or two thoughts about migratory populations: There are many, many individuals, many retired, who come from Canada and our northern tier of states to many locations along the Rio Grande Valley for winter.

I think, too, of foreign workers in places such as Europe (I saw them in Germany, Gastarbeiters--guest workers, when I was there '72-'73) and those from Mexico who come to the United States.

Students, too.

They come to work or to relax or to learn.

Posted by: laloomis | May 7, 2009 11:36 AM | Report abuse

And lasers. But not on sharks.

Posted by: yellojkt | May 7, 2009 11:41 AM | Report abuse

I'm done for today with Schneider v Kissinger. They were invoking Marbury v Madison before it was all over. My head hurts. A judge was replaced with a Bush appointee, Rosemary M. Collyer. I have no idea of the justification, but I'm fairly sure of the reason... for anyone who cares:

Posted by: Jumper1 | May 7, 2009 11:41 AM | Report abuse

That closet's getting smaller and smaller... David Ogden Stiers is out.

Posted by: Scottynuke | May 7, 2009 11:45 AM | Report abuse

I wrote a computer program once and I thought it modeled infections in populations pretty well for such a simple program. Each node is assigned a transmitability value at random. The "infection" of the entire group does not proceed linearly. As the permitted random values in each test run increased incrementally (by me), all of a sudden at a certain point the "epidemic" almost always establishes very quickly.

Posted by: Jumper1 | May 7, 2009 11:49 AM | Report abuse

I don't know about anybody else in the DC area, but my garden plot turned into a 200 square foot mud puddle in the last few days with all the rain. I doubt I could walk across it without losing my shoes. So no planting for me for at least another week.

Posted by: WhackyWeasel | May 7, 2009 11:59 AM | Report abuse

Scotty, Is it worth noting that the percentage of Americans who call themselves Republican is approaching the percentage of Americans who are gay.

Possibly, could it be that Republicans are going into the closet while gays are coming out?

Posted by: russianthistle | May 7, 2009 12:01 PM | Report abuse

Was he ever truly in it, Scottynuke? I'm glad he felt he could speak out at last.

Posted by: Wilbrod_Gnome | May 7, 2009 12:01 PM | Report abuse

New kit, complete with front page link/alert

Posted by: curmudgeon-1 | May 7, 2009 12:04 PM | Report abuse

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