Talk:Snake venom

I'd like to begin revamping this article. I thought that a snake venoms should be put in a context of (1) all venoms, (2) specific adaptations for the survival of snakes, (3) human morbidity and mortality, and (4) applications to pharmaceuticals etc. My first edits are going to be pragmatic - based on full text literature that I have access to remotely. I hope that those who are interested join in editing the article and engaging in discussion here in discussion. Nancy Sculerati MD

References Used in Rewriting The Article

I intend, on a first pass rough draft, only to include footnotes as I would if I were submitting this review for a medical textbook or a review article for a peer reviewed journal. In either case, I would give specific references only for direct quotes, or to cite an important contribution made to the literature for the first time, or perhaps to reference a controversial issue. I would not and in my professional contributions to textbooks and peer reviewed literature -have not) make a footnote for facts that are generally known by MDs and PhDs familiar with the field, or that are repeated in multiple papers. However, as I think the points raised about using references to guide the reader are valid, I would like to keep track of actual references I do read in composing this article. Therefore I suggest we give this a try - here's a list of references consulted in writing this article. I will keep it as a running list as I contribute, and hopefully others will too, as they do the same. This might be a useful trail to leave on the discussion pages of all articles as we write and edit on Citizendium, or perhaps we could add an additional tab: "references" up there with "article", "discussion" etc.

(1)Encyclopedia of Life Sciences Copyright © 2006 by John Wiley & Sons, Inc. All Rights Reserved. Last updated: 20 Sep 2006 1.a)Article: Venoms W Dias da Silva, Thereza L Kipnis Standard article Published online: 25 April, 2001 1.B Article: Envenoming: Consequences and Management David A Warrell Standard article Published online: 29 January, 2003

(2)Schmidt JM. Antivenom therapy for snakebites in children: is there evidence?. [Review] [26 refs] [Journal Article. Review] Current Opinion in Pediatrics. 17(2):234-8, 2005 Apr. UI: 15800419

(3)Lewis RL. Gutmann L. Snake venoms and the neuromuscular junction. [Review] [26 refs] [Journal Article. Review] Seminars in Neurology. 24(2):175-9, 2004 Jun. UI: 15257514

(4)Warrell DA. Bites of venomous snakes.[comment]. [Comment. Letter] New England Journal of Medicine. 347(22):1804-5; author reply 1804-5, 2002 Nov 28. UI: 12456862

(5)Filippovich I. Sorokina N. Masci PP. de Jersey J. Whitaker AN. Winzor DJ. Gaffney PJ. Lavin MF. A family of textilinin genes, two of which encode proteins with antihaemorrhagic properties. [Journal Article] British Journal of Haematology. 119(2):376-84, 2002 Nov.

(6) Gold BS. Dart RC. Barish RA. Bites of venomous snakes.[see comment]. [Review] [37 refs] [Journal Article. Review] New England Journal of Medicine. 347(5):347-56, 2002 Aug 1. UI: 12151473

(7)Currie BJ. Clinical toxicology: a tropical Australian perspective. [Review] [3 refs] [Journal Article. Review] Therapeutic Drug Monitoring. 22(1):73-8, 2000 Feb. UI: 10688264

(8)White J. Bites and stings from venomous animals: a global overview. [Review] [10 refs] [Journal Article. Review] Therapeutic Drug Monitoring. 22(1):65-8, 2000 Feb. UI: 10688262

(9)Senior K. Taking the bite out of snake venoms. [News] Lancet. 353(9168):1946, 1999 Jun 5. UI: 10371585

(10) Trinh, Kiem Xuan; Trinh, Long Xuan; et al. The Production Of bungarus Candidus Antivenom From Horses Immunized With Venom & it's Application For The Treatment Of Snake Bite Patients In Vietnam: 75. Therapeutic Drug Monitoring. 27(2):230, April 2005.

(11)Prescott, Ruth A. BSc (Hons, London) *; Potter, Paul C. MB, ChB, MD, FCP(SA), BSc (Hons) *+ Hypersensitivity to airborne spitting cobra snake venom. Annals of Allergy, Asthma, & Immunology. 94(5):600-603, May 2005.

(12)Harris, J B 1; Goonetilleke, A 2 Animal poisons and the nervous system: what the neurologist needs to know. Neurology in Practice. 75 Supplement III:iii40-iii46, September 2004.

(13) Confronting the Neglected Problem of Snake Bite Envenoming: The Need for a Global Partnership Gutiérrez JM, Theakston RDG, Warrell DA PLoS Medicine Vol. 3, No. 6, e150 doi:10.1371/journal.pmed.0030150

(14) Ontogenetic Variation in Venom Composition and Diet of Crotalus oreganus concolor: A Case of Venom Paedomorphosis?Stephen P. Mackessy, Kwame Williams, Kyle G. Ashton Copeia Volume 2003, Issue 4 (December 2003) pp. 769–782 DOI: 10.1643/HA03-037.1

(15) Comparison of Active Venom Components between Eastern Brown Snakes Collected from South Australia and Queensland Simone Flight1, 3 , Peter Mirtschin2 and Paul P. Masci3 Ecotoxicology © Springer Science+Business Media, Inc. 2005

(16)Mackessy S.P. 2002. Biochemistry and phamacology of colubrid snake venoms. J. Toxicol.-Toxin Rev. 21: 43–83.

(17) Avila-Aguero ML. Paris MM. Hu S. Peterson PK. Gutierrez JM. Lomonte B. Faingezicht I. Snakebite Study Group. Systemic cytokine response in children bitten by snakes in Costa Rica. [Clinical Trial. Journal Article. Randomized Controlled Trial] Pediatric Emergency Care. 17(6):425-9, 2001 Dec. UI: 11753186

(18) Sano-Martins IS. Tomy SC. Campolina D. Dias MB. de Castro SC. de Sousa-e-Silva MC. Amaral CF. Rezende NA. Kamiguti AS. Warrell DA. Theakston RD. Coagulopathy following lethal and non-lethal envenoming of humans by the South American rattlesnake (Crotalus durissus) in Brazil. [Journal Article] Qjm. 94(10):551-9, 2001 Oct. UI: 11588214

(19) Ben Abraham R. Winkler E. Eshel G. Barzilay Z. Paret G. Snakebite poisoning in children--a call for unified clinical guidelines. [Journal Article. Multicenter Study] European Journal of Emergency Medicine. 8(3):189-92, 2001 Sep. UI: 11587463 (note: covers Israel)

(20) Lee BC. Hwang SH. Bae JC. Kwon SB. Brainstem infarction following Korean viper bite. [Case Reports. Journal Article] Neurology. 56(9):1244-5, 2001 May 8. UI: 11342702

(21) Tanen DA. Ruha AM. Graeme KA. Curry SC. Fischione MA. Rattlesnake envenomations: unusual case presentations. [Case Reports. Journal Article] Archives of Internal Medicine. 161(3):474-9, 2001 Feb 12. UI: 11176775 (includes several case history of individuals intoxicated with alcohol who purposely handled rattlesnakes)

(22)Suchard JR. LoVecchio F. Envenomations by rattlesnakes thought to be dead. [Case Reports. Letter] New England Journal of Medicine. 340(24):1930, 1999 Jun 17. UI: 10375322 (also incudes case histories of intoxicated people handling rattlesnakes)

(23)Boyer LV. Seifert SA. Clark RF. McNally JT. Williams SR. Nordt SP. Walter FG. Dart RC. Recurrent and persistent coagulopathy following pit viper envenomation. [Journal Article] Archives of Internal Medicine. 159(7):706-10, 1999 Apr 12. UI: 10218750 (article cites cases where coagulopathy lasted 2 weeks +)

(24)Milani Junior R. Jorge MT. de Campos FP. Martins FP. Bousso A. Cardoso JL. Ribeiro LA. Fan HW. Franca FO. Sano-Martins IS. Cardoso D. Ide Fernandez C. Fernandes JC. Aldred VL. Sandoval MP. Puorto G. Theakston RD. Warrell DA. Snake bites by the jararacucu (Bothrops jararacussu): clinicopathological studies of 29 proven cases in Sao Paulo State, Brazil. [Case Reports. Journal Article] Qjm. 90(5):323-34, 1997 May. UI: 9205667

(25) Murthy JM. Kishore LT. Naidu KS. Cerebral infarction after envenomation by viper.[erratum appears in J Comput Assist Tomogr 1997 May-Jun;21(3):followi]. [Case Reports. Journal Article] Journal of Computer Assisted Tomography. 21(1):35-7, 1997 Jan-Feb. UI: 9022766 (India, case history young man, pit viper bite, CT scan images)

(26)Ramirez M.S., Sanchez E.E., Garcia-Prieto C., Perez J.C., Rodriguez Chapa G., McKeller M.R., Ramirez R., De Anda Y. Screening for fibrinolytic activity in eight Viperid venoms(1999) Comparative Biochemistry and Physiology - C Pharmacology Toxicology and Endocrinology, 124 (1), pp. 91-98.

(27)Asher O. Lupu-Meiri M. Jensen BS. Paperna T. Oron Y. Fuchs S. How does the mongoose cope with alpha-bungarotoxin? Analysis of the mongoose muscle AChR alpha-subunit. [Journal Article] Annals of the New York Academy of Sciences. 841:97-100, 1998 May 13. UI: 9668225

(28)Pramit Chowdhury, Muriel Gondry, Roger Genet, Jean-Louis Martin, André Ménez, Michel Négrerie, Jacob W. Petrich Picosecond Dynamics of a Peptide from the Acetylcholine Receptor Interacting with a Neurotoxin Probed by Tailored Tryptophan Fluorescence Photochemistry and Photobiology Volume 77, Issue 2 (February 2003) pp. 151–157 (Toxin α from Naja nigricollis)

(29)Gaballa M. Taher T. Brodin LA. van der Linden J. O'Reilly K. Hui W. Brass N. Cheung PK. Grip L. Images in cardiovascular medicine. Myocardial infarction as a rare consequence of a snakebite: diagnosis with novel echocardiographic tissue Doppler techniques. [Case Reports. Journal Article] Circulation. 112(11):e140-2, 2005 Sep 13. UI: 16157777 (clear explanation of how venom initiating DIC can cause myocardial infarction from coronary artery clot)

How many snake species- how many are venomous?

I have found so many numbers here that disagree I thought I'd keep tack of them, and hopefully sort this out into some reasonable statement. On reviewing the titles of articles on snake species in such journals as Copeia over several years, it is apparent that the number of snake species has been changing. With the advent of DNA sequencing and other forms of genomic testing, some species that had thought to be different based on morphologic examination of hemi-penes, etc, have been lumped together, and with initial herpetological examination of some geographic regions, new species have been described. This may account for the variation reported in the number of snake species and the number of venomous species in various articles on snake venoms in the medical literature.Nancy Sculerati MD

1)"There are ~2340 species of snakes living on the earth and more than 420 species are venomous." quoted from Lewis RL. Gutmann L. Snake venoms and the neuromuscular junction. [Review] [26 refs] [Journal Article. Review] Seminars in Neurology. 24(2):175-9, 2004 Jun. UI: 15257514 who reference Herdon G Dowling's Book: Dowling HG, Duellman WE. Systematic Herpetology: A Synopsis of Families and Higher Categories. New York: Hiss Publications; 1978:100–102

2) Approximately 15 percent of the 3000 species of snakes found worldwide are considered to be dangerous to humans quoted from Gold BS. Dart RC. Barish RA. Bites of venomous snakes.[see comment]. [Review] [37 refs] [Journal Article. Review] New England Journal of Medicine. 347(5):347-56, 2002 Aug 1. UI: 12151473

3)There are more than 3,000 species of snakes in the world, but only about 350 species are venomous and only the minority of these are likely to cause significant envenoming in humans. -this is followed by a statement that 4 families of venomous snakes exist - leaving out the sea snakes.White J. Bites and stings from venomous animals: a global overview. [Review] [10 refs] [Journal Article. Review] Therapeutic Drug Monitoring. 22(1):65-8, 2000 Feb. UI: 10688262

The best figures I can give you are "over 2.500 species of living snakes" according to McDiarmid et al. (1999). This is a figure mentioned in the first of a multi-volume checklist, subsequent volumes of which have yet to be published. The on-line ITIS database is based on that first volume, as well as Dr. McDiarmid's working manuscript for the next one. Luckily, the lists of venomous snakes seem to be complete and I've counted them for you:

Atractaspididae	Mole vipers, African burrowing asps, stiletto snakes	64
Elapidae	Cobras, kraits, coral snakes, mambas, sea snakes	321
Viperidae	Vipers, pit vipers, rattlesnakes	217
Total		602

There are also quite a few colubrids that are can considered venomous, but only three that I know of have been the cause of any documented fatalities. That would bring the total to 605, or about 24% of all known species of snakes. --Jaap Winius 14:32, 26 December 2006 (CST)

Thanks, Jaap. Look at the second line of the article as it now stands. I just wanted to have some sort of general overview of numbers of snake species and to indicate the fact that the venemous kinds are a minority. If you would like to reword it, or drop it, please do. I've been struggling with how to say it. Nancy Sculerati MD

Image

Nancy, would be this image necessary? --Versuri 17:06, 25 December 2006 (CST)

Just a minor nudge really. AchE really works by degrading free ACh not by inactivating bound ACh - binding is a dynamic short lived process anyway so molecules are continually hopping on and off, reducing the extracellular concentration keeps this short. Think that's about the limits of my particular knowledge - alpha bungarotoxin is still used very extensively in characterising receptors. Article looking good, and I'll pop by now and again, see how I can helpGareth Leng 09:07, 26 December 2006 (CST)

Aaargh - sorry Nancy, edit conflict, I'll run away for a bit....Gareth Leng 14:49, 26 December 2006 (CST)

Jaap, you edited out :The danger to a human from any particular species of venomous snake depends on many factors. First, there is the toxicity of that species venom, which can vary from mildly harmful to highly lethal. Second, there is the actual dose of venom that the snake can deliver effectively in an attack. Finally, there is the likelihood that any individual snake will attack a person if confronted, rather than withdraw. No species of snake takes human beings as a preferred prey. Even in the case of venemous snakes able to kill a person with a bite, "interactions between snakes and people are most often lethal to the snake" without any explanation, and changed it to reflect the same view that you seem to have expressed in that Eastern coral snake article where we first "met". That view seems to be summarized by the idea that the only thing that matters is how toxic the venom is and how much is available for secretion. The world's literature on snakebite in humans disagrees with you, the liklihood that the snake will bite and the effectiveness of the deliveery system also seem to matter. Why do you remove my words without explanation, Jaap? Additionally, your faith in the exact number of species of snakes and venemous snakes shows diligence on your part, but seems to be naive of the actual workings of scientists who classify animals. There are always disagreements about exactly which species are truly separate, further, venom in a snake is not in any way defined as something that causes human harm. Perhapa I 've misunderstood your rationale for such exact numbers, or for your explanation of how you decided which snakes were venemous. Perhaps you did provide an explanation for your change about the danger of human proximity to a venemous snake that you made. If I have misunderstood, please clarify. Citizendium is a collaborate effort and sometimes requires diplomatic clarification. Nancy Sculerati MD

Sorry, sorry. I guess I was thinking that was material carried over from the old WP version. Actually, I spent a while expanding that little section before I removed it. It looked like this:

• The toxicity of the venom.
• Average venom yield.
• General temperament -- how they are likely to react when disturbed. For example, some are more likely to stand their ground rather than flee.
• Whether or not they are attracted to human habitation.
• How widespread a species is.
• Population density within its range.

The last three are factors that increase the likelyhood of unfortunate encounters; they don't make individual specimens any more or less dangerous, but they can make all the difference between a species being termed "medically significant" or not.

Notice also that I say "react when disturbed" as opposed to "attack", since snakes never do that: they only defend themselves. People attack snakes, but snakes only attack they prey (which does not include people).

Anyway, it was late (4:30 AM) and it was at this point I started thinking that the entire paragraph was looking more like something that belongs in a natural history article as opposed to one on snake venom. Now that I think of it, though, you could put it back in saying that venom toxicity and yield are only two factors that make a species dangerous. I'll bet that was what you intended in the first place.

Anyway, I didn't mean to offend and apologize if I did. I think you're doing an excellent job and hope you will continue. --Jaap Winius 07:58, 27 December 2006 (CST)

apology accepted ;-) by the way, that "venom toxicty and yield" being the whole of the determinants was what I objected to! I agree with your outline above, but would also add something about the snake's apparatus for envenomation.However, I also agree with you that this is an article on the venom, and not really on the "venemous snake bite". Certainly, they are related and something about the snake bite must be said- probably best in the area I have left most blank- under each family. Jaap, if you have references for the change from the 5 families (a term I find amusing because in New York, it is a phrase typically used to refer to the Mafia) to superfamily Couloubridae (probably mis-spelled, sorry, off the top of my head) containing 4 families of venemous snakes, could you put it here? Meanwhile, there is more to say about the toxins and I will keep working. It's tricky because these toxins invoke the most powerful (and complicated) reactions and to do this article justice, I really have to update my knowledge of the basic science of blood clotting, inflammation, and tissue necrosis. These have all been greatly refined in last few years with advances in molecular biology. I'm enjoying learning but it makes the amount of work much greater. We are lucky to have a number of excellent people in the biology workgroup to keep us on track!(Thanks, Gareth!)

I suggest that we keep everything we write on venemous snake bite here for the moment, although I don't intend to move back the phrases we just discussed above yet, and when the article gets too long, we can split off an article on snake bite. I will also be working on trying to make the hyperlinks to those topics of blood clotting, etc easier to understand and more accurate, so if I take a break I will come back. Nancy Sculerati MD

Mongooses

Mongooses do have genetic variations in their acetylcholine receptors that make the receptors resistant to at least one of the toxins that bind to them, and so there really are specializations. True, it's not immunity. I'm putting back the lanaguage that was recently changed. Note that the outline heading was changed from "Immunity" to "Immunity and Resistance". Just like there are genetric variations in people to resist malaria (sickle cell trait), I have found several reports of gene modification of proteins in mongoose and hedgehogs that actually do, on a physiological basis, make these animals "resistant". I have not found any references so far that tests their survival (thankfully) but the molecular biology is really interesting. By the way, there is nothing left at this point of the old Wikipedia article, and if anybody can removed that boilerplate announcement that the article was originally written from it, it would be helpful.Nancy Sculerati MD