I read about this study on LiveScience, and then went to the Nov. 4 issue of The New England Journal of Medicine to check it out. It turns out to be true, and perhaps the case of the unluckiest person on the planet. Well, there are others who die from bad luck (what we call “the unexpected results of the laws of physics”), but this guy died from a quintuple whammy:
- He contracted HIV
- He also got tapeworms.
- One of those tapeworms got “cancer,” probably via a somatic mutation in one of its stem cells
- The HIV, weakening his immune system, prevented him from fighting off the neoplasm, which invaded his body from the tapeworm.
- The tapeworm cancer spread and ultimately killed him.
This appears to be the first known case of a human dying from a cancer caught from a parasite. Here’s a screenshot of the article; clicking on it will take you to a summary page where, I think, you can download the full pdf:
The short story: a 41-year old man in Medellín, Colombia, presented with fever, fatigue, and cough. Stool and body examination revealed cysts of the dwarf tapeworm Hymenolepis nana (one of the most common human tapeworms, usually caught from rodents), as well as cancerous-looking masses in his liver, abdomen and lungs. The cells, however, were not typical of human cancers. The masses proliferated in the lymph nodes, and five months later the man died.
Here’s one figure from the paper showing the tumors and some features of the cells. The caption for these panels is from the paper:
Figure 1 Radiographic and Pathological Features of Malignant Hymenolepis nana. Anteroposterior and axial CT scans in Panels A and B, respectively, show the presence of lung nodules. Panel C shows a biopsy specimen from a cervical lymph node containing firm, solid masses. Panel D shows small, atypical cells in an air-dried lymph-node touch preparation stained with Diff-Quik.
DNA sequencing of the tumorous masses showed that they derived from H. nana; in other words, they were cancers from a tapeworm. Although these tapeworms weren’t previously known to get cancers, it’s likely that a mutation in the tapeworm’s stem cells, combined with the patient’s compromised immune system, led to the formation of these tumors.
What’s the lesson? It’s not yet clear. They didn’t use human cancer treatments against these masses (the man got anti-tapeworm drugs and anti-retroviral medication), so they’re not sure that will work. But it’s possible that this kind of disease is more widespread than we think, and goes largely undetected because infected patients either don’t present themselves or die of HIV. It’s also not clear whether a person uninfected with HIV could get such malignancies; perhaps an uncompromised immune system could have fought off the mutant tapeworm cells.
The lesson is stay away from dodgey rodents.
Also from tapeworms and mutants.
Please do not let the B-movie horror industry hear about this. “Invasion of the mutant tapeworms”.
Incidentally, on a less frivolous note, I’ve often wondered why HIV and hepatitis isn’t transmitted by mosquitos? (We’re damn fortunate it isn’t!)
cr
I’ve wonder that, too. You have prompted me to find out why. Google is my friend!
It’s mainly because mosquitos don’t inject blood into their victims, just saliva. HIV virus isn’t in the right place at the right time.
Whereas malaria (which is the obvious comparison) apparently is transmitted in saliva.
Informative article you linked to. Thanks.
cr
On a related note, I’ve often wondered if the contagious oral cancer found in Tasmanian Devils, either the original or the newly discovered form, is transmissible to human beings.
I was thinking of that new contagious cancer too!
The paper claim it is entirely new. (Y chromosome phenotype, different microsatellites and what not; I don’t think they have excluded cell fusion though.
And considering the young ages of both cancer diseases they are rethinking how they emerge and spread. [There is also a canine infectious cancer, as well as one among clams IIRC, not to forget how HeLa cells can survive independently…]
To riff of the thread’s theme: “Invasion of the mutant body cells!”
Don’t ever kiss a Tasmanian Devil.
As I understand it, there are plenty of other reasons not to get up close and intimate with a Tasmanian Devil, especially if you value keeping all your extremities attached to yourself.
cr
Sage advice.
Abbie Smith explains this on her blog ERV:
http://scienceblogs.com/erv/2008/09/22/okay-so-there-are-like/
It is quite complicated, but essentially a molecule called MHC 1, which is involved in the immune response that would normally eliminate the cancer before it could get going, only exists as a single variant in Tasmanian devils, and the cancer has found a way to get round this variant. Human beings have >800 variants, so almost all human beings are not susceptible, and the disease could never get going.
I think it shouldn’t be, unless the human is heavily immunocompromised, and in this case any cancer should be contagious to him (data anyone?).
I figured the lesson was that if we looked more closely at cases where people died of full blown AIDS we’ll probably find new, interesting, and horrifying things that happen which would normally be prevented by the immune system. Like tape worm stem cells growing all over your body. It was my understanding that we don’t normally look too deeply since the ultimate cause is known and out of consideration for families.
In the early period of the AIDS epidemic, the existence of the then new disease was noted because of increases in the numbers of homosexuals getting rare kinds of pneumonia and cancer. Illnesses that doctors did not expect to see in their careers were becoming common.
I thought at first this might be one of your parody click-bait headlines.
Unfortunately, turns out to be the awful truth.
Oooh, I hope Vincent Racaniello, Dickson Despommier, and Daniel Griffin here about this, as it would make a fantastic TwiP episode (This Week in Parasitism).
here=hear, of course (homophone cursed)
It actually was in their last episode of TWiP.
Sweet 🙂
Hm! I didn’t know cancer was sometimes contagious! Another myth of childhood shattered.
Unfortunately a similar phenomenon is sometimes seen in human organ transplantation. If cancer cells exist in a donated organ they can continue to multiply and even metastasise in the recipient. In such cases it is the immunosuppressive drugs rather than HIV that allow the foreign cells to proliferate. Thankfully it’s pretty rare – it only happens once or twice a year in the UK out of several thousand transplants.
Gruesomely fascinating! Just what we need–infectious cancers.
more infectious cancers. Poor Taz. And poor tapeworm man.
Indeed. Random abstract courtesy of Google:
–“The search for infectious causes of human cancers: Where and why”
Virology, Volume 392, Issue 1, Pages 1-10
Harald zur Hausen
I have a vague memory the Helicobacter got fingered for some cancers too. Though that may be mediated by it’s better known habit of messing up the gut for it’s own purposes.
The same team has also described immunocompromised patients infected with Hymenolepis dying of massive infection with larvae disseminating through their bodies:
http://www.ncbi.nlm.nih.gov/pubmed/12792874
The healthy immune system, though unable to eliminate the parasite, at least keeps it restricted to the gut.