Steven Barritz (left) and Travis Bautista pose with their brand new copies of the revised edition of Parasite Rex with a new epilogue. I’ll be sending them an autographed book plate. If you’d like one, here are the steps:

1. Buy a copy.

2. Email me a picture of yourself with the book (it’s marked “with a new epilogue”).

3. I’ll reply to your email and we’ll make arrangements to send you an autographed book plate. (You’ll need to cover the cost of the postage and plate, which should be about a buck.)

Brian Malow and I talked yesterday about some of my favorite things on the latest episode of Dr. Kiki’s Science Hour–including the evolution odometer. You can watch it on Youtube, or you can head over to Dr. Kiki’s Science Hour site to download the video or audio. (The Skype goes berserk briefly, but we get back on track.)

In 1996 I had just turned thirty. If you had told me at the time that parasites were about to become an integral part of my life for years to come, I would have said, “Oh, look at the time! I’ve got to go feed my hyrax!” and headed for the nearest restroom to scrub my hands.

But it would have been true. I just had finished my first book, and I was wondering what to write next. I had a couple vague ideas I bounced around with my agent over lunch. How about an exploration of the intersection of biology and philosophy? A blank look. How about a book about parasites? Boom: my agent sat up.

That decision led me to some interesting places: rebel-held territory in southern Sudan, a Costa Rican jungle, a salt marsh in California, and the official United States Parasite Collection. And not too long afterwards, I finished writing Parasite Rex.

The book has thrived ever since. Recently, my publisher decided to put out a new paperback edition, to celebrate the ten year anniversary of the original paperback. I’ve written an epilogue for the new edition, in which I reflect on the experience of writing–and living with–the book. It made blind dates a bit awkward, to say the least, but it also gave me a piece of tapeworm eternity: Anthrobothrium zimmeri.

This is the first time I’ve had a reissued book come out, so I’m thinking of ways to mark the occasion. (If anybody is inspired to invite me on their radio show, you know where to find me!)

Here’s one plan I have. If you’d like me to autograph the new edition, follow these steps:

1. Buy a copy.

2. Email me a picture of yourself with the new edition (it’s got “with a new epilogue” in red at the bottom).

3. I’ll reply to your email and we’ll make arrangements to send you an autographed book plate. (You’ll need to cover the cost of the plate and postage; I still have to figure out the cost, but I assume it should be in the neighborhood of $1.)

Here’s one mock-up I’ve been playing around with. Any other suggestions?

[Update: Buy link fixed.]

I’ve got two stories in the New York Times tomorrow, at two ends of life’s scales.

In the cover story, I write about smiles. Faces have long fascinated me (see this Discover column on Darwin and Botox), and so I was intrigued to come across this recent paper focusing on smiles in particular. I talked to David Corcoran about the story for the first twelve minutes of the latest  Science Times podcast.

Elsewhere in the Science Times, I keep up with the creepiest form of life out there: infectious cancer. Two species–Tasmanian devils and dogs–have given rise to cancer cells that can hop from host to host. I wrote about Tasmanian devils in the Times, and about dogs here at the Loom. Now there’s news that the dog cancer (which I want to call Canis cancer after talking to the scientists who study it) rejuvenates itself from time to time by stealing its host’s mitochondria. This is a story that just keeps going and going…like the cancer themselves.

Susan Perkins at the American Museum of Natural History is almost done with a truly heroic feat: overseeing a blog that features a new parasite every day in 2010. As we glide towards the end of the year, she’s launched “The Twelve Parasites of Christmas.” So far, mistletoe (that botanical equivalent of a tapeworm!), two turtle doves (and their blood parasites), and the cauliflower mushroom, bane of Christmas trees. What gifts await us in the next week?

The nightmare that is the cholera epidemic of Haiti (2,100 dead so far) has become a little less mysterious. Haiti has not seen cholera for over a cenutry, and so the emergence of cholera in recent weeks has puzzled scientists and led to riots directed at the U.N. for supposedly bringing Vibrio cholerae to the Caribbean nation. Others have pointed to a New World strain as a potential culprit. It triggered an outbreak in Peru in 1991, and has circulated in Central and South America ever since. Perhaps these bacteria washed up on Haiti’s shores.

In the latest issue of the New England Journal of Medicine, Matthew Waldor of Harvard and his colleagues go some distance to settling the debate by finding the Haitian cholera’s place in the tree of life.

“Collectively, our data strongly suggest that the Haitian epidemic began with introduction of a V. cholerae strain into Haiti by human activity from a distant geographic source,” the scientists write. The bacteria belong to a strain that evolved in South Asia. It was probably introduced onto Haiti by a sick person who flew there. We may never know who made the delivery, but it was a terrible blow not just to Haiti but perhaps to other New World countries. The South Asian strain is, unfortunately, deadlier than the Peru strain and resistant to antibiotics to boot. Waldor and his colleagues warn that unless the bacteria are stopped now, they could outcompete the milder Peru strain.

“Clearly, the provision of adequate sanitation and clean water is essential for preventing the further spread of the Haitian cholera epidemic,” they write. Let’s hope we can prune future branches of this deadly tree.

Recently I paid a visit to a place where the world’s most mysterious viruses go to find a name. The result was my profile of Ian Lipkin of Columbia University for tomorrow’s New York Times. I first started thinking about this story when I heard Lipkin give a lecture about his work identifying unknown viruses this spring. And when I read this review of Lipkin’s, entitled simply, “Microbe Hunting,” I knew it was time to get cracking.

One thing I didn’t have room for is the fact that Lipkin has gone all Hollywood. By which I mean that he’s helping Steven Soderbergh on a new movie on a virus outbreak called Contagion, starring Matt Damon, Kate Winslet, and other big stars. Lipkin seems pretty stoked about the movie, which is slated for 2011, so I’ll definitely be keeping an eye out for it.

Scientists have known for decades that the genomes of animals can sometimes harbor DNA from the viruses that have infected them. When I first learned of this fact some years ago, it blew my mind. The notion that any animal could be a little bit viral blurred nature’s boundaries.

The viruses that scientists discovered in host genomes were of a particular sort, known as endogenous retroviruses. Retroviruses, which include HIV and a number of viruses that can trigger cancer, have to insert their genetic material into their host’s genome in order to reproduce. The cell reads their genetic instructions along with its own, and then builds new viruses. It made a certain intuitive sense that retroviruses might sometimes get trapped in their host genomes, to be passed down from one generation to the next.

The first endogenous retroviruses scientists identified were still relatively functional. Under certain circumstances, their genes could still give rise to new viruses that could break out of their host cell. But gradually, scientists identified more and more fossil viruses, which had mutated so much that they could no longer reproduce. As I wrote in the New York Times in 2006, scientists have even figured out how to resurrect these fossil viruses from the human genome.

That would have been weird enough. But nature is generous with its weirdness. As I wrote in the Times earlier this year, scientists have started finding viral stretches of DNA in our genomes that are not retroviruses. In that article, I focused on the discovery of genes from bornaviruses, which just park themselves next to our DNA, rather than inserting their genes into our own.

New kinds of endogenous viruses keep turning up as scientists looked closer. Today in the journal PLOS Genetics, Aris Katzourakis of the University of Oxford and Robert Gifford of New York University offer a particularly startling survey of the viral world within. Rather than searching for one particular kind of virus, they hunted for a wide range of them. Their collection reflected all the different ways that viruses can replicate inside mammal cells. They then hunted for the sequences of these viruses in the genomes of 44 mammal species, plus a handful of birds and invertebrates. The scientists struck viral gold. Every major group of viruses turned up in the host genomes.

In most cases, the viruses infected their own host. But the scientists also found mammal viruses integrated into the genomes of ticks and mosquitoes–perhaps as a result of their feeding on virus-infected mammal blood. In many cases, viruses slipped into their host genomes a long, long time ago. The scientists discovered segments of bornavirus present not just in humans, but in monkeys from the Old World and New World. We share a common ancestor with monkeys that lived some 54 million years ago. What’s more, one of these bornavirus segments is very similar in many of its hosts today. That uniformity suggests that it has taken on a useful function in our own bodies. Scientists have already found evidence that endogenous viruses can help build placentas and fight off other viruses; now bornaviruses can be added to the list.

This is one of those exploding fields that is a joy to follow. I’m glad that this new paper came out before I had to turn in my proofs for my next book, called A Planet of Viruses, which will be coming out in May. But I’m sure that the catalog of inner viruses will be growing a lot longer in years to come.

[Update: Ed Yong is also infected with curiosity.]

I’m going to be a guest on Road Dog Trucking Radio, the satellite radio channel for truckers. I’m going to talk about parasites, viruses, and other weird critters. Even if you don’t drive a big rig, you’re welcome to tune in.

I’m a big fan of All in the Mind, a radio program on neuroscience, psychology, and all things brain-ish, produced by Natasha Mitchell for Australia’s ABC Radio National. So it’s a double pleasure to hear her new episode about how parasites alter behavior. Check it out.

If you’re looking for a gang of vicious killers, look no further than the Apicomplexans. These single-celled protozoans cause death and destruction across the animal kingdom. They infect everything from butterflies to people. Their diseases include Texas Cattle Fever, toxoplasmosis, and the scourge that makes Plasmodium the baddest Apicomplexan of them all, malaria.

Scientists have named 6,000 apicomplexans, but they estimate there may be anywhere between 1.2 and 10 million species waiting to be identified. Every apicomplexan they’d studied so far is equipped with the same fearsome weaponry. Their cells are shaped like teardrops, and at the pointed end they have a ring of tubes, like the chambers on a revolver. When an apicomplexan prepares to invade a cell, it points those chambers at its prospective host and fires a set of molecules that grab the cell’s surface and stretch it open so that the apicomplexan can slide in. Apicomplexans inherited their weaponry from their common ancestor, which lived several hundred million years ago, and they’ve thrived as pathogens ever since.

Yet in the midst of this brutal dynasty, scientists have now discovered a peacemaker. For the first time, they’ve found an apicomplexan that bestows a biochemical gift to its host essential for survival.

The host for this peculiar creature is a tiny animal known as the sea grape. It’s basically a miniature blob that sits on underwater rocks along the coast of the eastern U.S., siphoning food from the passing water. Despite the outward differences between us and sea grapes, we’re pretty closely related. In fact, sea grapes belong to the lineage of invertebrates that’s most closely related to vertebrates. They even develop a notochord, a stiff rod supporting the spinal cord, just as we vertebrates do.

As far back as 1874, biologists noticed some strange “parasitic elements” inside sea grapes. They lurked in an organ known as the renal sac, which is believed to purify the sea grape’s blood much as our kidneys do. Sea grapes are the only animals beside humans known to make kidney stones, and yet they can somehow destroy the stones in their renal sacs.

Some researchers guessed the parasite elements were fungi, dubbing them Nephromyces: “kidney fungus.” But the closer scientists looked at this strange fungus, the less parasitic it looked. Every sea grape scientists have looked at (every member of the genus Molgula to be specific) carries a massive infection of Nephromyces in its renal sac. Yet they’re not born with Nephromyces; every new generation of sea grapes have to be infected by it all over again, picking it up in the surrounding sea water. Likewise, Nephromyces only lives inside sea grapes, and inside sea grapes they only live in the renal sac, where they go through dramatic changes as they move their the stages of their life cycle.

Mary Beth Saffo has been studying this strange association for 20 years (here’s a 1994 profile in the New York Times), and she thinks it’s an intimate partnership. The sea grapes give Nephromyces a shelter and a never-ending buffet: its kidney stones. In exchange, Nephromyces produces nutritious compounds from the stones that the sea grapes can use. Actually, Saffo suspects, it’s a three-way partnership, because Nephromyces harbors bacteria that helps it break down the stones.

To get a better understanding of Nephromyces, Saffo and her colleagues recently fished out some of its DNA. They had reason to doubt that the DNA would reveal Nephromyces to indeed be a fungus. It didn’t have any traits that were unique to any group of fungi, and it had also some peculiar features not found in any fungi; in one stage, they sprout a pair of swimming tails. But it would have been hard to have predicted Nephromyces was an apicomplexan, belonging to a lineage of millions of species of parasites. Yet that’s what its DNA clearly shows.

In retrospect, perhaps earlier scientists could have guessed it was an apicomplexan after all. It has some structures at one end that look like the revolver cylinders of more familiar apicomplexans. And when Nephromyces first gets into a sea grape’s bloodstream, it takes on a worm-like shape, slithering along until it finds the renal sac. That’s the same form that Plasmodium takes when it is injected by a biting mosquito and slithers through the blood stream to find the liver. But instead of causing a disease like malaria, as Plasmodium does, Nephromyces proceeds to cure its host of gout.

Saffo is not the first biologist to discover a parasite turned mutualist. But it’s hard to think of another case in which a species has turned its back on such a huge legacy of death and disease. How it made such a massive swing is left for Saffo and others still to figure out. It’s possible that once Nephromyces picked up its bacterial passengers, it could thrive inside sea grapes without making them sick. Perhaps in order to put its old ways behind, a parasite just needs a little help from its friends.

Reference: Saffo et al, “Nephromyces, a beneficial apicomplexan symbiont in marine animals.” PNAS. http://www.pnas.org/cgi/doi/10.1073/pnas.1002335107 (Link will start working at some point this week.)

[Images courtesy of Mary Beth Saffo]

[Update: 8/24/10 9:30am: A few minor fact-checking corrections.]

I had planned to spend today NOT writing about parasites, but this morning I’ve already gotten comments and tweets informing me about a very cool new paper that was published today, documenting parasitized zombies 48 million years ago.

All right, then. The parasite overlords cannot be ignored.

The parasite in question is the fiendishly awesome Cordyceps, a fungus that forces its insect hosts to climb up high on plants, clamp down, and hold fast. The fungus then sprouts out of the ant’s body, showering down spores on hapless insects below. I wrote about Cordyceps in my book Parasite Rex, and followed up last year with a blog post on some great work by David Hughes of the University of Exeter and Harvard. Hughes and his colleagues wondered if the fungus was controlling its host in a fine-tuned adaptation, or if the ants were becoming zombies because they were just sick. After all, if your body was shot through with fungus threads, you’d probably feel lousy as well. But Hughes made a strong case that Cordyceps really is in charge, because it so consistently sends its hosts to the same kind of place in the canopy, finding a location that benefits the parasite. The parasitized insects even bite down on the same place on a leaf.

Out of this research, Hughes got a brilliant yet very simple idea. If Cordyceps causes its hosts to behave in such a fixed way, maybe that behavior has been preserved in the fossil record. Hughes and his colleagues went through a big collection of 48-million-year-old fossil leaves in Germany and discovered a leaf with distinctive snips that closely match those made today by Cordyceps-infected ants.

There’s precious little evidence of parasitism in the fossil record. It’s not surprising when you consider the delicate, squishy nature of most parasites. Most of the evidence scientists have found is indirect. The bacteria Mycobacteria tuberculosis, for example, leaves scars on the bones of some of its victims, including–possibly–a 500,000-year-old hominid with TB.  Hughes’s new paper is important because it points not just to a particular parasite 48 million years ago, but a particular form of parasite manipulation. Ancient fungi appear to have evolved all the sophisticated biochemistry they needed to control an animal a very long time ago, and they’ve been using it to manipulate insect hosts ever since.

This new research is just a tiny glimpse into what is, I’m sure, a vast world of paleoparasitology. Parasitism is the most successful way of life today, and there’s no reason to think that wasn’t true 100 million years ago. Where there are hosts, there are parasites, and lots of them. Let’s see if scientists can continue to think up new ways to open up that world and document the parasitic history of life on Earth. Whether they’ll discover dinosaur tapeworms, I don’t know. But I can hope.

(You can read more about Cordyceps from Ed Yong and Nature)

[Image: David Hughes]