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  • Bitten by a venomous snake?

  • Well, you probably shouldn't waste three precious minutes watching this video,

  • but if you're going to do it anyway, I can tell you

  • that there is hope.

  • Some animals have a natural resistance to snake venom

  • like the snake-eating Honey Badger

  • which can be bitten in the face by a cobra and still not care

  • but for people, historically, you just had two choices:

  • you could either just hope you'd recover, or you could just die.

  • A lot of the time, you did both.

  • but all that changed with Albert Calmette,

  • French researcher, dedicated public health advocate, and co-creator of the tuberculosis vaccine

  • Calmette also developed the first snake antivenom in the late 1890s.

  • The story goes that Calmette was sent to Saigon, in what is now Vietnam

  • by his mentor Louis Pasteur, one of the fathers of microbiology,

  • to help inoculate people against smallpox and rabies.

  • One day, a major flood swept through his village, flushing up a bunch of monocled cobras that started biting everyone.

  • but Calmette was like "nuh-uh, snakes!"

  • and, being an expert in the business of vaccine making, he whipped up an antivenom called "Calmette's serum"

  • His technique was so solid that it remains largely unchanged today.

  • Antivenom works by stimulating the production of antibodies

  • the highly specialised warrior proteins released by your immune system to neutralise dangerous antigens

  • like viruses, bacteria, or, in this case, venom.

  • Antivenom can't destroy a venom's toxins or reverse its ill effects

  • but the antibodies they create can smother them, preventing further spread and rendering them harmless.

  • And here's how you make it.

  • Step one: get some venom.

  • To make antivenom, you need venom. And if you're wondering about the name, yes -

  • you can also call it "antivenin" if you want to; "venin" is actually the French word,

  • and since he was French, that's what it was originally called

  • But a while back, the World Health Organisation decided that, in English at least, "antivenom" made a lot more sense.

  • Anyway, to make an antidote for venom, you need a lot of it

  • so, once you've got your bag of deadly snakes, grab one, open its mouth over a vial, and gently squeeze its venom glands until they're empty.

  • You'll only get a little bit at a time, so multiple snakes must be "milked", as they call it, many times

  • to get enough venom.

  • Fun.

  • For example, in 1965, the National Institute of Health told famed snake-wrangler Bill Haast

  • to collect about half a litre of Coral Snake venom.

  • It took him 69,000 milkings, over a three-year period, to reach that goal.

  • Step 2: Freeze the venom.

  • Once the snake is milked, the venom is freeze-dried to concentrate and preserve it.

  • Step 3: use some other animal to make antibodies.

  • Find a horse, sheep, or goat, and inject them with little doses of the venom again and again

  • over several weeks.

  • This allows the animal to build antibodies and fight off the venom

  • The antibodies peak after a couple of months, at which point they can be harvested

  • by which, I mean that up to 6 litres of blood is typically drained from the animal's jugular.

  • But don't worry; the animal isn't bled to death. It will live on to enjoy the process all over again.

  • Step 4: Purify, concentrate, and deliver.

  • After the bloodletting is done, you filter out the antibodies, and then purify and concentrate them into dose vials

  • If you need it, like, RIGHT NOW, then good!

  • But if you're just going to store it up for the next snake-handling encounter, then stash it in the freezer.

  • The fact that antivenom must be kept cold poses a serious problem for developing countries with scarce electricity.

  • Unfortunately, those tend to be the same places that are inundated with killer snakes.

  • You've probably noticed by now that this whole process isn't easy.

  • Making antivenom is expensive and time-consuming, which is one reason why it suffers global supply shortages all the time.

  • A single vial may cost over $1500, and a victim may require 20 to 30 vials to fully recover

  • from a serious bite.

  • But, there are other ways!

  • Remember Bill Haast, and his half-litre of snake spit?

  • He practiced a form of mithridatism, the process of making yourself immune to a toxin by gradually taking non-lethal amounts.

  • He milked 100 snakes a day with his bare hands

  • and made his own, decidedly lower-tech, antivenom

  • leaving the horses out of it and using his own body.

  • He pretty much single-handedly saved 21 snakebite victims by flying around the world,

  • donating transfusions of his own blood.

  • He lived to be 100 years old, surviving 172 snake bites, and only losing one finger

  • to which I say... DANG!

  • Thank you for watching this episode of SciShow

  • If you have any questions or comments or suggestions, you can find us on Facebook or Twitter

  • Or, of course, down in the comments below

  • and if you want to keep getting smarter with us, you can go to youtube.com/scishow, and subscribe.

Bitten by a venomous snake?

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B2 中高級 美國腔

如何製作抗蛇毒血清 (How To Make Antivenom)

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    robert 發佈於 2021 年 01 月 14 日
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