土拨鼠竟是腺鼠疫的起源?

GUY RAZ, host:

Take a listen to this next sound I'm about to play.

(Soundbite of prairie dog)

RAZ: That's the North American prairie dog, and some scientists believe they speak one of the most complex languages on the planet. Now, for a while, researchers have been trying to figure out why the bubonic plague, the same one that brought black death to Europe, why it's been wiping out entire prairie dog villages.

Well, a group from Stanford may have cracked the mystery. James Holland Jones, who's an anthropologist, studies the spread of infectious diseases, and he believes the plague is spread by tiny fleas that live on the backs of grasshopper mice; mice that move freely among prairie dog families, known as coteries.

Professor JAMES HOLLAND JONES (Anthropology, Stanford University): Well, what happens is when a coterie is wiped out, you've got these prairie dog fleas that are now in pretty desperate straits, and the grasshopper mice are a convenient host that they can jump onto.

RAZ: So the grasshopper mice are underground in the prairie dog towns just passing through. These fleas are killing a family of prairie dogs. They need blood; they jump on the mice.

Mr. JONES: That's right. And the mice, you know, are not completely passive in this either. The mice are perfectly happy to eat the carcass of a prairie dog that's died of plague. And that's a really terrific opportunity for these infected fleas to jump onto the mouse, and then the mouse carries them off to the next susceptible coterie.

RAZ: Now, I should mention that you are an anthropologist. You are not a prairie dog expert.

Mr. JONES: That's right.

RAZ: You sort of study, in part, study how disease is spread. Why are prairie dogs more susceptible to the plague?

Mr. JONES: Well, I think that it has to do with the fact that prairie dogs live in towns. They form almost a lattice of little individual family units within this enormous town of a couple thousand individuals. And so what this means is that you have all this fuel for an epidemic to burn off of, essentially. You know, you have these thousands of prairie dogs in one place.

RAZ: Living in closed quarters.

Mr. JONES: That's right. Whereas, you know, some other rodent species that isn't social like the prairie dog is, it may not have enough social interactions to sort of allow a pathogen to persist in transmission chains.

RAZ: It seems like the way they live is so similar in some ways to the way human live.

Mr. JONES: Absolutely. We got structuring, right? We got structuring by the spaces in which we live. We got structuring by the ways we work and the way we travel. And these structures, these social structures, have enormous consequences for the dynamics of infectious disease spread.

RAZ: Now, the plague, the black plague...

Mr. JONES: That's right.

RAZ: ...affected Europe primarily in the 14th century, Killed, what, something like 200 million people. Does this tell us or sort of give us a better understanding of how that plague spread?

Mr. JONES: Well, it gives us a better understanding of how epidemics, particularly with multiple hosts, spread. The plague in Europe, the black dust in the 14th century, you have this alternative host, you have these rats that would carry fleas between human families. People lived in big cities, These cities during the middle ages arose in part for not protection from predators but protection from other people. You know, there is a certain sort of superficial similarity to it.

RAZ: That's James Holland Jones. He's an anthropologist at Stanford University. His paper on plague and prairie dogs appears in the proceedings of the National Academy of Sciences.

James Holland Jones, thank you so much.

Mr. JONES: Thanks, Guy. It was fun.