The danger of anti-venom

[dannybgoode]

Looking through the whole herping threads reminded me of a story about my dad.

Whilst we do not have many snakes England and they're quite a rare find my dad did manage to get bitten by an adder when he was a teenager. Thought it was a grass snake. Whilst the bite was very painful it was the anti-venom that very nearly killed him.

He was allergic to one of the ingredients they use in almost all anti-venoms (the horse serum? I may have got that competely wrong but it rings a bell) and he ended up in intensive care in hospital because of it and was genuinely close to death. The doctors said if he ever had it again it would almost certainly kill him.

Not so much of a problem when he lived in England but when he moved to Australia! He had to where a medical bracelet advising no anti-venom. Basically of he got bit by any of the venomous creatures out there be would have had to ride his chances. Whilst some of the snakes, spiders, fish etc could have probably killed be the anti-venom definitely would.

He was very, very careful!

Has anyone else heard of this allergy?

[Nightflight99]

This is a very common problem, and part of the reason why some manufacturers have moved away from horse serum.

[dannybgoode]

This is a very common problem, and part of the reason why some manufacturers have moved away from horse serum.

Interesting. And I was right about the horse serum :) and not going mad with age!

What is horse serum and is there a reason it is so commonly used? And what causes the reaction - is it like anaphylactic?

[Nightflight99]

Basically, the traditional way of producing antivenin is to inject a small, but increasing amount of venom into horses, who develop the proper antibodies, which are then isolated and administered to the human victim. If your body reacts to the horse antibodies, it begins to manufacture its own antibodies against them, which produces an immune reaction (serum sickness). Once your body has produced those antibodies, it will trigger a much more severe immune response to any subsequent exposure of horse serum.

[dannybgoode]

Thanks NF - that's really interesting. As I say it wasn't a issue when he lived in England but it was one of the few things that made him nervous about Australia.

He said he saw many of his neighbours do the gardening without gloves and just in flip flops or sandles which he thought was madness. He looked like he was off out fighting bush fires!

I had to help him squash some redbacks which where hiding under some garden furniture we were going to use for a party - he wouldn't go anywhere near them!

[trailblazer295]

Very interesting read.

Your dad picked the worst place possible to move to. lol

[travesty]

I've been watching Venom ER and they say that antivenin used to give bad reactions too a lot of people. Apparently the new CroFab doesn't give bad reactions like the old stuff did. Don't know what they use in Australia though.

[dannybgoode]

He moved out to Oz 30 years ago when it was still very much used. Bit tough knowing that if you were bitten you'd just have to ride it out...

[PatrickT]

as far as i know anti venom is a venom itself that can kill. Its a small balance and you can easily cross the line

[MDT]

The technology today is much better than the equine products. The method used to "clean up the antibodies" is amazing. Historically, the whole antibody (Fab and Fc portion) were utilized (Wyeth anti-venin in America). It was the whole protein that your immune system would recognize as foreign and bad, beginning the allergic cascade and often leading to anaphylaxis.

I had the opportunity during my residency to treat a kid bitten by a pygmy rattlesnake (and this was before CroFab), and of course the patient had allergic rxn to the Wyeth product. Had to keep patient on IV steroids and benadryl during a very slow infusion process of the anti-venin. Patient did ok eventually, but is was scary for a bit.

CroFab (and now Anavip) bypass this by removing the immunogenic Fc portion of the immunoglobulin molecule. Very clean drug compared to what we used to have to use.
I think most anti-venom producers world-wide are utilizing this method now.

[pet_snake_78]

Best not to get bitten by any dangerously venomous snakes, but should I ever, I'll certainly take my chances with AV if required.

[Nightflight99]

About ten years ago, I developed serum sickness after receiving an exotic equine-based monovalent antivenin. Prior to that experience, I had always considered serum sickness to be a mere inconvenience, and was shocked how severe the immune reaction was. Add to that the fact that the corresponding memory lymphocytes enjoy a tremendous longevity, and it begins to paint a realistic picture of just how significant the longterm repercussions of a bite can be.