Tasmanian Devils and contagious cancer

Tasmanian Devils, the real-life marsupial inspiration behind the cartoon beastie, were already an endangered species when nature added insult to injury. In 1996, researchers first formally described Devil Facial Tumor Disease, a cancer that would later turn out to be contagious, passed from devil to devil by biting, mating, and sharing food.

While you're probably familiar with the idea that viruses can cause cancer, that's not what's going on here. Instead, the cancer cells themselves are contagious. It's a rare phenomenon, but not (terrifyingly enough) completely unique. At Nature blogs, Anne-Marie Hodge writes about other cases of contagious cancers in mammals.

One prime example is canine transmissible venereal tumor (CTVT), a histiocytic tumor that is passed between dogs through sex as well as sniffing and licking of the genitals. At one point it was thought that a sexually transmitted virus, similar to HPV, caused this disease. It turns out, however, that it is the CTVT cells themselves that are infectious, not a virus that activates them. The cancerous cells themselves, which are essentially clonal, are what is passed from animal to animal.

For example, when an infected Dog A has genital contact with Dog B, what is transmitted is not some agent (such as a virus) that triggers Dog B's cells to start dividing and creating tumors. Instead it is the cancer cells themselves, which are genetically different from both Dog A and Dog B, which continue to clone themselves on their new victim. Thus it seems animal that receives CTVT from its mate is not so much infected as colonized, and that is why CTVT is sometimes referred to as a "parasitic cancer." The tumors most often appear on the external genitalia, but may also affect the nose and mouth.

There are few interesting aspects of CTVT cells. While normal dog and wolf cells contain 78 chromosomes, the tumor cells have fewer, usually between 57-64, and even those chromosomes bear some distinct morphological differences from those found in healthy dog tissue. The disease also infects coyotes (which also have 78 chromosomes) and red foxes (with only 34 chromosomes).

Image: Wikipedia user Wayne McLean via CC

Via Bora Zivkovic


  1. tg:dr

    (too gross, didn’t read)

    Sorry, tasmanian devils, about all the cancer. Cute little buggers.

  2. In the early 70’s, I remember getting our set of Encyclopedia Britannica Junior. They sat right next to the couch and I used them to look up everything I questioned on T.V. As if it was yesterday, I remember reading about the Tasmanian Devil. 

    Today, about 40 years later, I still TRY to tell people that Tasmanian Devils are real and the one on Looney Toons really isn’t that much different. Most don’t believe me. ( Or when I tell my friends WHO LIVE IN N.Y.C  that coyotes live in the alleys of Manhattan: http://cityroom.blogs.nytimes.com/2010/03/24/coyote-takes-tribeca/. )

  3. reminds me of reading about Heinretta Lack’s cancerous cells infecting every other first line of cell cultures (why it was the first successful culture; it’s still a potent contaminant apparently).

    1. some scientists classify HeLa and similar cell lines as a separate species. In fact the first post-human species.  On the other hand some creationists still refuse to take this as an observed speciation event

  4. I was reading about this a few weeks ago. I was under the impression that the reason why this particular cancer was infectious had nothing to do with the cancer, but was due to the fact that the devils have identical immune systems, so that when they bite each other, the cells transfer to the new host and grow out. 
    I’m not sure that a transfer of cancer from one host to another without any metabolic input from the new host actually defines ‘infectious’. 

    1. It sounds more like a parasite than an infection to this layperson.  But when I stop and think about it, I’m not really all that sure what the difference is between harboring a parasite and having an infection.

  5. The Radiolab episode is awesome. They all are. They point out that since it is a single continuous line, CTVT can be regarded as the oldest living organism on Earth.

  6. Fascinating. We can only wonder why God caused this cancer-parasite creature to be whisked into existence 10k years ago.

    1. Whoa, I was just going to comment on that gorgeous mouth – what teeth! – but, yeah, loookit that sac… (completely missed it till you mentioned it)

  7. In one of the “Howling” movies they decided that Tasmanian Devils were the source of werewolves via something like this transmittable cancer!

  8. sad to hear that now a cancer it trying to wipe out the tasminian devil .for they may be vicious but they look some what cute. would hate to see the  thing extinct due to cancer.

    1. They are very very territorial about anything and with anyone. They are loud and quick to snap. They were named devils because of the noises thy made at night fighting over food. They have a terrible strong and fast bite

      The getting mad makes them cuter in a way. You can kind of see the skin on the inside of it’s ear? That changes color with the tazzy’s rapidly spiking blood pressure and rage. It goes from pink to red to beat red to purple as it gets more upset with you.

      That said people can be affectionate to Devils. I not sure the devils are that affectionate in return.
      My daughter loved this guy for the affection he showed to Tazzys.

      1. Great video.

        Devils’s jaws are the strongest in the world for their size. The pressure exerted by their bite is comparable to a that of a salt-water crocodile. Devils eat carrion, and have been known to completely consume an animal as big as a horse, except perhaps for the pelvis. They play rough, too; most devils bear scars from competition for food but also just from rough horseplay.

        I’ve loved these amazing creatures since visited the devil breeding operation (breeding immune animals) at Taronna: http://www.tasmaniandevilpark.com. They are adorable. Tasmania’s got a lot of spectacular wildlife; we saw an endangered wedge-tailed eagle there, in the wild, which even got our local Tassie guide excited. But nothing compares to the devils. What an incredible sound they make!

        1. Devils’s jaws are the strongest in the world for their size.

          I thought that solfugids had that honor.

  9. But…but…but…banana!  *demonstrates how a banana fits perfectly in the human hand*

  10. Unfortunately it seems the Tassie Devil’s days are numbered. If it happens Tassie will have lost the two largest carnivorous marsupials on the planet. Man’s unfortunately already knocked out the Tasmanian Tiger, which resembled a dog much more than a cat, let’s hope man’s conservation efforts help keep this species alive.

  11. It is rare because our immune systems are all different and very good at spotting non-self cells but this does occasionally happen in humans:


    From the article:
    “In the US, around 3500 women each year get cancer while they’re pregnant. Melanoma, acute leukaemia and carcinoma are examples of cancers that have been passed from mother to fetus. Acute leukaemia cells have also been passed from baby to baby in multiple births. Another possible – but rare – route of tumour cell transmission is organ transplantation. There is also a case of a surgeon who injured his hand during an operation to remove a tumour from the abdomen of a patient. Some five months later, the surgeon found a swelling at the site of injury that was shown to be a tumour with the same genetic origin as that of the patient.”

  12. Large balls usually mean promiscuous females, and therefore sperm competition.

    Chimpanzees, for example, have huge balls because females screw around constantly (basically in order to protect their young by making it unclear who the father is — of course not a conscious decision, but one rewarded by natural selection), whereas gorillas have pathetic, tiny little balls, since a male with a harem need not fear sperm competition (and also since sex is so infrequent with gorillas — somewhere between never and extremely rarely).

  13. Makes me wonder if this is merely an experimental stage in the “sexually transmitted cancer” experiment?  After all, even such a small crisis can certainly not be wasted!  The majority MUST and WILL think that this came from some ‘wild’ animal.  It couldn’t have possibly been created in a lab even though it is genetically different from the animals infected.  Huh?  I am not sure  whether it is even naturally possible to have cells that are not genetically similar?  After all can’t paternity be proven with the DNA of a sibling of the father?   Also, I always thought that a parasite was something that invades a body, for instance a tapeworm. 

    1. I’m not entirely sure that you’re serious.

      If cancer was genetically identical to the individual it infects, it wouldn’t be cancer.  Cancer is caused by damage or mutation in the DNA. 

      Now please keep in mind that there are very few Tasmanian Devils.  That means the gene pool is relatively shallow, if you will.  Is it not impossible that some individuals are so genetically close that their own body does not recognize the cancer as foreign?  In other words, that the cancer is metastasizing not across organs, but individuals? 

      Is it possible that maybe if someone wanted to create an infectious cancer in some “lab” somewhere, they might pick a species a little more discreet than the Tasmanian Devil?  Like, say… dogs? 

      Finally, I can understand why you might think of a parasite as an individual organism invading a body, but that doesn’t mean other things can’t act like parasites, including tumors.  I’m also not really sure how much of an impact your linguistic opinions may have on technical terminology.

  14. Offitopic: Maybe they’ve been around for a while and I’ve only just noticed because I’ve switched from Chrome to Safari and so no longer have AdBlock, but man Boing Boing — those are some *cheesy* looking ads up there. [Ads by engage:BDR]

  15. interesting to note…not a whole lot of the posters mentioned “contagious cancer” and “mammal” and linked it to another “mammal”… one poster gave several examples of contagious cancer in humans…and there are other documented cases… most people are only worried about the Tasmanian Devil…. weird…

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