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Comment by fsckboy | Hacker News Reader

FTA:

>Why do so few researchers study them?

>In the fall of 1985, Scott L. Gardner found himself standing over his toilet bowl, fishing around in the squishy output of his empty bowels with a chopstick.

fsckboy's law of headlines: If the headline asks a question, check if the first sentence has your answer

>...Gardner was prescribed an antiparasitic pill, and the next morning, he pooped out his intestines’ inhabitant—all 12 inches of it.

irl, my brother got a parasite once, a tapeworm. This was all without leaving an upscale suburb of Boston. Only "noticed" it when he, a well-built vigorous athlete, lost a lot of weight out of the blue. It was eating his lunch, so to speak.

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> It was eating his lunch, so to speak

How does that work. A tapeworm is pretty small relative to your brother (eg by mass), one would think it's caloric needs are similarly small and it would just use a small fraction of his food. Can a tapeworm really consume a significant fraction of an adult's food?

there are different types of tapeworms that infect different hosts. cattle tapeworms can grow to 12 feet and much more. It doesn't take much googling to find claims of 100 feet.

google "tapeworm symptom loss of weight" and you will get the recommendation "time to see a doctor"

So the explanation would be that growing is just very metabolically expensive and that is where the deficit goes to?

I'm no expert on invertebrate metabolism, but it does not need to be more expensive than host metabolism, it's simply a redivision of the pizza-pie with more slices going to the growing worm, and fewer slices for the host.

consider the possibility of there being n worms in the host (person), where n is greater than 1, maybe even significantly greater than 1.

so if one worm takes m slices of the pie, and there are n worms in the person, there will be m x n less slices available for the person, which, depending on the values of m and n, could be quite high, and therefore much more detrimental to the person

I thought of a refinement to my previous: tapeworms attach themselves to the host intestinal wall only to secure themselves; however, they feed directly from the food in the digestive tract; they do not "suck nutrients" from the host's bloodstream.

It's not a tapeworm but here's an example of a parasite that does:

https://en.wikipedia.org/wiki/Ancylostoma_duodenale

It's the stuff of nightmares.

That's part of it, but intestinal parasites also interfere with normal digestive processes. Their presence and secretions (waste products and the compounds they use to prevent being digested) can cause a lot of problems. It's common for people with intestinal parasites to have reduced appetite, intestinal inflammation, and digestion issues.

The weight loss isn't just a result of the parasite competing for nutrients, though that doesn't help.

At the Meguro Parasitological Museum [1], they have an 8 meter long tapeworm [2] extracted from a human. Yes, that is an extreme example and still less mass than a person, but they can get large.

[1] https://www.kiseichu.org/e-top

[2] Visible in the tall blue case here: https://static.wixstatic.com/media/079dcd_843c7597ef244423aa...

Bigger picture of it: https://www.tofugu.com/travel/parasite-museum-tokyo/

The display has a piece of rope, so that you can get a not-too-intimate sense of its length.

Apart of eating your food directly, anything that can make you bleed internally can cause anemia.

Okay but: when he stepped on the scale, he was weighing himself and the tapeworm. A tapeworm can't just magically eat your lunch and send the calories into another dimension.

There's got to be something else to it, like that your belly feels strange and you lose your appetite.

Suddenly losing a lot of weight points toward dehydration, for one thing.

Maybe if the guy was well muscled he needed a constant influx of protein, also. Breakdown of muscle which is mostly water doesn't translate to a lot of calories.

Most athletes will probably notice if their fat content lowers or their diet doesn't bring the desired effects.

People with tapeworms visibly look like they have lost weight. They notice from the mirror, not the scale.

Not always. Plenty of people with tapeworms in them will present with few or no symptoms. If they feel anything at all, it'll probably be the usual inespecific gastrointestinal symptoms like abdominal pain, nausea and diarrhea.

Varies from person to person. Could take years before the thing is big enough to cause any real damage. I've seen cases where people had parasites inside them without noticing for what must have been decades without any treatment.

Doctors in endemic regions often won't even bother with tests, they'll treat you straight up. Good old albendazole, once a year. In certain places people routinely go to the doctor to ask them to prescribe the medicine whether they feel anything or not.

Tapeworms eating your food is definitely a very popular idea. Sometimes I see some exceedingly clever humans trying to use them as a poor man's semaglutide. They usually get zero results but sometimes they lose some serious weight alright, most of it water.

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