Fatal bites from non-venomous snakes

[rafal]

Hi,

I've had a lively discussion recently about bites from non-venomous snakes. Friend of mine found information that a significant number of people die from those bites because they are so convinced that the snake was venomous. I couldn't find any information to prove or disprove that theory. I know that the shock is really great, even if you know that snake is non-venomous, but is it possible that it is lethal? Do you know any statistics? Of course, I am aware that it can happen because somebody can be allergic, have problem with a heart, etc. I'd like to know if it happens on any significant rate, i.e. 40% of all deaths from snakebites is caused by non-venomous snakes.

Thank you!
Rafal

[stephanbakir]

First of all, most snakes are venomous on some level. The vast majority are just so mild you'd never know without having the venom tested.

Brian Grieg Fry wrote a few good papers on it, you can find them at Venomdoc.com

I didn't quite understand the question, but if your asking how many people were killed by the bite itself I can't think of my offhand. The only time the bite itself will kill you is if they get you on an artery or you are allergic and go into anaphylaxis.

[MDT]

Rafal, I would be careful about accepting your friend's "information" without know the authorship. If it's not from a peer reviewed scientics publication, it's likely not worth much. When envenomations occurs, the proteins, peptides, kinins, etc in the venom that cause cellular destruction (whether blood cells, endothelial cells, cardiac, neural, etc). Allergic reaction does not work this way. Typically, if someone in a specific region presents with a snakebite, the treating physician (should) know the most likely source...if in an area of high puff adder population and someone presents with a swollen, black, bleb filled arm, it's prob not allergic However, my comments are only from my experience with treating North American pit viper bites (specifically Oklahoma)...I have never seen a "bad reaction" or death from a non venomous bite.
Stephens suggestion of Dr Fry's work is spot on. Check out venomdoc.com
I would postulate that death from a "non venomous bite" is extremely rare if not completely non existent.

[MDT]

weird....I just saw this posted on another forum...

Pythons are still a little venomous – Phenomena: Not Exactly Rocket Science

Very good read, and study conducted by none other than Dr. Fry himself. This may not directly answer your question, however, the statement in the article:

"His also found venom proteins in the constricting pythons and boas, and in iguanians. The levels are too low to be used as a defence or to kill prey (although the more predatory iguanians did have more protein-secreting cells in these glands—maybe a killing role isn’t out of the question). “Nothing in evolution is every really lost,” Fry says. Even if venom glands have been repurposed for making mucus, you’d expect them to still produce traces of venom."

may point you in the right direction....

[stephanbakir]

Your body can also be allergic to just about any protein, an allergic reaction will kill you faster then most things if it is severe enough.

[MDT]

Originally Posted by stephanbakir

Your body can also be allergic to just about any protein, an allergic reaction will kill you faster then most things if it is severe enough.

yep....true anaphylaxis will kill you DRT.

[stephanbakir]

It's overkill to carry things like an epipen in a collection of "non venomous" snakes, but every first aid kit in a collection of hots should have at least one.
A few people I know have 2-3 of them. I'll need to check my notes to be sure but their effects last 15 mins per pen? Or something like that

Even with "mild" venoms that take hours to kill you, a bad allergic reaction will kill you in minutes without intervention.

[Kettennatter]

It took only 5 minutes for my dad to pass away after a severe allergic reaction to a wasp's sting. He had no idea he was allergic.

[stephanbakir]

Anaphylaxis is an incredibly quick killer, that doesn't give time for second chances to the ill prepared

Sorry about your dad, I had a really bad reaction to Crofab (I believe it's bovine antivenin as opposed to equine av) had I not been in in a hospital at the time I'd also be dead.

[MDT]

CroFab is ovine (sheep) not bovine or equine. Reactions to CroFab are rare and usually managed without incident.....however, every now and then you get someone who really wants to jack up your shift and have a bad reaction....Shame on you Stephan!!

What bit you? Can you share some of your clinical information, like grade of envenomation, number of vials of CroFab you needed, etc...? If we need to start another thread so as not to jack Rafal's thread, no worries...or PM?

[stephanbakir]

Long story short I was bitten by a naja kaouthia and they gave me Crofab (wtf!!! I know...) and it wasn't til I talked with Kim later that I made the connection and flipped my **** at the doctor. If I remember I got at least 7 vials, I was talking with a few SI friends, and a few venom response people and they not know how I survived, there shouldn't be cross protection between naja and Crotalid av.

I blew out pretty bad, I've got scars but even they aren't too bad. I Astrox bite was worse, and in that case I didn't react badly at all, to the same av. When I got bitten by the naja, I broke out into hives all over, my tongue swelled and took almost 2 years to fully heal (it kept sloughing its skin... I had dead tongue in my mouth and it tasted horrible til about 3 months ago. My immunologist had no idea why it would keep progressing and then regressing long after the allergen was in my system.

[Roman]

The big question is

What is a venomous snake?

As stephanbakir already said, a lot of “non-venomous” snakes (and lizards) have toxic components in their saliva. Because they have either no enlarged fangs or have enlarged fangs in the rear of their mouth the venom usually does not get into a wound if a human gets bitten, at least not in a large enough quantity to cause any harm.

So the most common definition for a venomous snake would be

- it is front-fanged
- the fangs have a direct connection to the “venom gland”

By this definition venomous snakes are the Elapids (cobras, mambas, sea-snakes etc.) and Vipers/Pitvipers (European, Asian and African Vipers, Rattlesnakes etc.).

But there is same grey area. What about the Boomslang (Dispholidus typus) or the bird snakes (Thelotornis sp.)? By definition, they are rear-fanged, but the fangs can (and will) be used in a bite and the venom is very dangerous for humans, both snakes have caused several fatal bites.

There is a very interesting book about this matter

Weinstein, Warrell, White, Keyler: “Venomous” Bites From Non-Venomous Snakes

They describe several cases of fatal or live-threatening envenomations by non-front-fanged colubrids.

Dispholidus typus
Thelotornis capensis
Thelotornis kirtlandii
Rhabdophis subminiatus (Asian keel-backs)
Rhabdophis tigrinus

Other snakes are reported to cause some serious medical problems but no proven fatal cases, e.g. Boiga irregularis.

@rafal about your question concerning medical symptoms caused because the people think the snake is venomous I found an interesting text in the book I mentioned above when they described another case of an unidentified snake bite

“Deeply ingrained communal fear of a particular animal can result in dramatic symptoms after bites, in the absence of any evidence that the animal is in any way venomous. In the Turkana region of northern Kenya, bites by Ruppell’s agama lizard (Agama ruppelli orientalis) are feared even more than bites by saw-scaled vipers (Echis pyramidum). Bitten patients may appear extremely ill or even comatose (MacCabe 2009). Around Freeport, West Papua, the blue-tongued skink (Tiliqua gigas) is feared more than the death adder (Asanthophis ssp.; DAW [David A. Warrell], personal communication[…]). These cases further illustrate the power of psyche in the generation of symptomatology.” (page 198)

So there are several non-venomous snakes which may cause serious medical problems or might even be fatal. Even a hognose might cause an envenomation if you let it chow long enough. However, it is difficult (or impossible) to quantify the amount of bites by non-venomous snakes, there are only few well documented cases.

Roman

[MDT]

@stephanbakir...Wow...CroFab for an elapid bite. I'll bet you were pissed, esp having a bad reaction. And, you are correct, there is no cross reactivity in CroFab to an elapid bite. It is made from venoms from eastern and western diamond backs, mojave rattlesnake and cotton mouth..all NA pit vipers. You were lucky

@Roman..you are correct, I'm not sure how anyone could quantify "death or serious injury" from a non venomous snake. My feeling (personal and not professional) that if you are bitten by a non venomous whatever and you were "scared to death"....that's on you and not the animal..

[MDT]

BTW...Weinstein is very active in venom research...He was on this forum for a bit. I haven't seen him on here in a long while. It's too bad. He knows his stuff.

[stephanbakir]

Personally I look at it as, contains an active protein (venom) which is harmful to life, or can cause significant physical damage.

All rear fang or front fanged snakes, including snakes like the red necked keelback(both poisonous, and venomous) pseudoxenodon ssp which are all considered to be non venomous in most books, but truly do have quite harmful venom.
I believe BGF wrote a paper on Boiga venom and most of them downright nasty. Luckily their method of delivery blows, and their venom yield is low.

I read his paper on the dissection of Calliophis bivirgatus and the size of its venom glands... WOW!!!