Neurophilosophy

Removal of a parasitic worm from the brain

Fox 10 News has a rather gruesome story about the removal of a live parasitic worm from a woman’s brain, which is accompanied by a film clip  containing footage of the surgical procedure.

As the film explains, the woman, who lives in Arizona, first started to experience flu-like symptoms, followed by numbness in her left arm which grew progressively worse. Neurosurgeon Peter Nakaji operated, expecting to find a tumour in the brainstem, but instead found and removed a tapeworm.

It goes on to say that the woman was infected either by eating uncooked pork or unwashed food contaminated with infected human faeces (making this most probably a pork tapeworm infection); that this was the sixth such case seen by Nakaji in the past few months; and that this is extremely rare but has started to increase recently.

Horrific as this all sounds, the woman in the film was in fact very fortunate, because if it had been the tapeworm larvae, instead of the worm itself, which had entered her brain, the consequences of her infection would have been much more severe.

The pork tapeworm, Taenia solium, is the most common brain parasite in the world: it has infected more than 50 million people, kills some 50,000 people every year and is the leading cause of epilepsy in parts of the developing world. T. solium is endemic in Latin America, and is therefore becoming a public health problem in the United States, due to immigration. In the southwestern U.S., this parasite accounts for about 10% of patients who visit emergency rooms with seizures.

The most serious consequence of infection is a disease called neurocysticercosis, which occurs when the larval cysts (or cysticerci) of the parasite enter the central nervous system and become lodged in the brain, spinal cord or eyes. When the cysts start to degenerate, they are engulfed by immune cells which try to destroy them, but which then clump together to form structures called granulomas, which harden as a result of calcium deposition. These calcified cysts, or lesions, are the pathological hallmarks of neurocysticercosis. The degenerating cysts can be 4 cm or more in diameter and so cause extensive tissue damage. The symptoms that occur as a result depend on the number  and location of cysticerci.

taenia_solium_scolex_close_up_400px.jpg

Most often, the cysts lodge in the grey matter, leading to epileptic seizures (see this new study which suggests that seizures are also associated with the fluid-filled cavities that surround the cysts);  if attached to the ventricles, they cause headaches, nausea, and dizziness; if in the cerebellum, the symptoms include impaired balance; and in the eye, blurred vision. Hydrocephalus and inflammation of the brain are also common symptoms, and often lead to severe brain damage or even sudden death as a result of cardiovascular problems.

However, T. solium has a complex life cycle which involves the pig as an intermediate host, and whether or not an infection leads to neurocysticercosis depends on when in the parasite’s life cycle the infection occured. Infection normally takes place by ingestion of cysticerci in uncooked meat. The cysts enter the small intestine and attach themselves to the intestinal wall with the scolex (above), an organ consisting of four large suckers and a double row of hooks. This then grows into an adult tapeworm, which can reach to up to 7 meters in length. Under some circumstances, a small adult worm can enter the brain.

An adult worm living in the intestine produces hundreds of thousands of eggs which are removed in the faeces, and so can easily be ingested in unsanitary conditions or because of unhygenic practices, thus completing the parasite’s life cycle. The eggs hatch upon exposure to the stomach acids and begin to grow into larvae called oncospheres which in turn develop to form cysticeri. These then enter the bloodstream and migrate to other parts of the body.

Comments

  1. #1 Mike W
    November 19, 2008

    that is so crazy… love it

  2. #2 Sara Nordmann
    November 20, 2008

    Gag. Doesn’t that sound like something out of the X-Files?

  3. #3 Klaus
    November 20, 2008

    It only gets some topic of X-Files when the worm starts manipulating the hosts behavior :) Like Toxoplasmosis, which makes women more friendly and warm and men more manlier (or something like this). At least thats what I’ve heard. When the parasite enters its intermediate host, a rat, it makes them less frightened of cat urine, which leads to a higher probability of the rat getting caught and eaten by a cat, which is the final host of the parasite.

    I don’t know whether this is really true, when I read this I think there was some note that the findings are not conclusive.

  4. #4 Tsu Dho Nimh
    November 20, 2008

    We also have the “brain-eating amoeba”, Naegleria fowleri, in this state.

    Aren’t we lucky?

  5. #5 Neuroskeptic
    November 20, 2008

    I’m pretty sure this featured in one of the early episodes of House…

  6. #6 quantum cephalopod
    November 20, 2008

    Heh. When asked his opinion on the large number of coincident cases of this worm treated in recent times, the doctor (speaking after the surgery part) coolly remarks: I think it’s a fluke. (my emphasis)

    Nice one!
    :)

  7. #7 Atila
    November 20, 2008

    It happened to me of being teaching about Taenia and one of the students had seven granulomas in the brain, with no apparent symptoms.

  8. #8 scicurious
    November 20, 2008

    Makes me SO glad I prefer Boca ‘meats’… I’m pretty sure that poor woman is off pork for life.

  9. #9 Erin
    November 20, 2008

    That is truly, horrifically disgusting.

  10. #10 Greg Peterson
    November 20, 2008

    With respect, because I know Pharyngula is the traditional place for going off on an anti-religionist rant, but “the power of prayer” worked? I know what she was trying to get at, because yes, it could have been worse, but it was after all a freaking WORM in her BRAIN. That’s not cool. And from what I saw, it wasn’t so much force of prayer that cured her; it was the application of forceps. If her faith in prayer helped her get through the horror of having her brain host a parasite, so be it and who would deny her that comfort. But I think the doctor and the people who painstakingly invented and perfected the methods of providing practical help to her merit at least some mention.

  11. #11 Rogue Epidemiologist
    November 20, 2008

    I see about a dozen cases of these each year, so other than being giddy while watching the video, color me unimpressed.

    A doctor in AZ should know enough to test immigrants (especially Latinos) who show up with a recent history of severe headache, seizures and visual disturbances for neurocysticercosis (and toxoplasmosis if you’ve got time). Get the serology and do a CT.

    We had one particular case this year, African (from Kenya) male who died alone in his sparse apartment, a few empty bottles scattered about the room. Say what you will about racial profiling, when the cops find a lone, deceased black man in a bad part of town, some would assume certain things. But not so. Coroner found neurocysticercosis to be the cause of death.

  12. #12 Luci
    November 20, 2008

    Mo watches Fox News? I’m crushed.
    The science is interesting – let’s hope for a more reliable source and follow-up on this horrendous public health issue.
    People sitting on the fence about choosing to eliminate meat from their diets may get a nudge here.

  13. #13 Rogue Epidemiologist
    November 20, 2008

    No, you just cook your pork chops a little better. Or you stay the hell away from people who are shedding eggs. That’s all. Taenia solium is not in the US pork supply. Hallelujah to that ’cause I like bacon.

    As for Fox News, I saw it on a Fox affiliate while waiting for ‘The Simpsons,’ so Mo might just be into watching Simpsons rerun and not Hannity & Colmes.

  14. #14 Mo
    November 20, 2008

    I am a fan of the Simpsons, but I found this via Google alert for “brain”-related news stories.

    @Klaus: Carl Zimmer has written a lot about toxoplasma, and this article by him might be where you read that the findings you mention were inconclusive.

  15. #15 Remis
    November 21, 2008

    @Neuroskeptic:

    1.- It’s actually the very first episode of House. The patient was allegedly jewish so House ruled it out, but when he realised that the patient ate ham, he used x-rays to rpove the patient that it was a tapeworm

    2.- It was not lupus. :-D

  16. #16 Chris
    November 23, 2008

    @Rogue Epidemiologist:
    Hey, can nurses do anything in epidemiology besides working as the “Infection Control Nurse” in the local hospital? – Thanks.

  17. #17 jeff
    November 24, 2008

    @Remis: you’re spot on. i actually did an extended medical review of that episode. i have heaps of snap shots from the episode. hop on to check it out!

  18. #18 Rogue Epidemiologist
    November 26, 2008

    @Chris
    Ain’t nothing wrong with being an ICP. ICP’s make my world go round. But if that’s not for you, you can be a nurse-epi in public health. However, the job’s pretty similar.

    If you want my job (which pays a lot less because I am *not* a nurse), then you’re gonna have to do a MPH with an emphasis in biostats/epi or infectious disease.

    @Remis
    One of the cysticercosis outbreaks often cited in the (scant body of) literature is an outbreak that happened in a Hasidic community in NY during the late 70′s. How do Hasidic Jews get neurocysticercosis? By hiring immigrants from Latin America to do their housekeeping. Apparently one of the hired hands was shedding eggs.

    It’s never lupus.

  19. #19 Stagyar zil Doggo
    November 28, 2008

    Rogue Epidemiologist:
    How do Hasidic Jews get neurocysticercosis?

    I’ve read that its easy enough for jews to get fish tapeworms by eating (or tasting) undercooked Gefilte fish. So much so that the symptoms are called “jewish housewife disease”. Don’t Fish Tapeworms cause Cysticercisos or Neurocysticercosis?

  20. #20 zay?flama šay?
    November 28, 2008

    I saw, it wasn’t so much force of prayer that cured her; it was the application of forceps.

  21. #21 Someone
    February 6, 2011

    My boyfriend has a brain parasite. I beileive this is what it is, a tapeworm. Im so scared for him. If any one knows, what is the chance of dying from this?

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