Talk:Snake venom

From Citizendium
Revision as of 16:54, 14 November 2007 by imported>Subpagination Bot (Add {{subpages}} and remove checklist (details))
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search
This article is developed but not approved.
 Main Article
 Discussion
Related Articles  [?]
Bibliography  [?]
External Links  [?]
Citable Version  [?]
 
To learn how to update the categories for this article, see here. To update categories, edit the metadata template.
 Definition:  Highly modified toxic saliva containing hydrolithic enzymes, polypeptide complexs, nucleases, and peptidases, that is produced by special glands of certain species of snakes. [d] [e]
Checklist and Archives
 Workgroup category:  Biology [Categories OK]
 Talk Archive:  none  English language variant:  British English

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) Gutiérrez JM, Theakston RDG, Warrell DA : 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)

(30) Gagandeep Singh, H.S. Pannu, P.S. Chawla, S. Malhotra: Neuromuscular transmission failure due to common krait (Bungarus caeruleus) envenomationMuscle & Nerve, Volume 22, Issue 12, Date: December 1999, Pages: 1637-1643

(31) I. B. Sundell R. D. G. Theakston A. S. Kamiguti R. J. Harris A. T. Treweeke G. D. Laing J. W. Fox D. A. Warrell and M. Zuzel: The inhibition of platelet aggregation and blood coagulation by Micropechis ikaheka venom. British Journal of Haematology Volume 114 Issue 4 Page 852 - September 2001 (discusses Metalloproteinases in elapid venom)

(32) Schneemann M. Cathomas R. Laidlaw ST. El Nahas AM. Theakston RD. Warrell DA. Life-threatening envenoming by the Saharan horned viper (Cerastes cerastes) causing micro-angiopathic haemolysis, coagulopathy and acute renal failure: clinical cases and review. [Case Reports. Journal Article] Qjm. 97(11):717-27, 2004 Nov. UI: 15496528 (includes case of pet horned viper biting owner while maintained in captivity in Switzerland)

(33)Moore GW. Savidge GF. Heterogeneity of Russell's viper venom affects the sensitivity of the dilute Russell's viper venom time to lupus anticoagulants. [Journal Article] Blood Coagulation & Fibrinolysis. 15(3):279-82, 2004 Apr. UI: 15060428 (discusses variations in the sensitivity of venom products depending on subspecies of snake, and includes tips for increasing yield of laboratory diagnosis of LA (lupus anticoagulants).

(34) R. Manjunatha Kini:Excitement ahead: structure, function and mechanism of snake venom phospholipase A2 enzymes. Toxicon. Volume 42, Issue 8 pp. 827-840 (December 2003) (Entire issue devoted to Myotoxic phospholipases. This article is a very well written review and discussion of snake venom PLA2)

(35) Schmitmeier S. Markland FS. Schonthal AH. Chen TC. Potent mimicry of fibronectin-induced intracellular signaling in glioma cells by the homodimeric snake venom disintegrin contortrostatin. [Journal Article] Neurosurgery. 57(1):141-53; discussion 141-53, 2005 Jul. UI: 15987550

(36) Stefansson S. Kini RM. Evans HJ. The inhibition of clotting complexes of the extrinsic coagulation cascade by the phospholipase A2 isoenzymes from Naja nigricollis venom. [Journal Article] Thrombosis Research. 55(4):481-91, 1989 Aug 15. UI: 2814939

(37) Singh G. Kuc RE. Maguire JJ. Fidock M. Davenport AP. Novel snake venom ligand dendroaspis natriuretic peptide is selective for natriuretic peptide receptor-A in human heart: downregulation of natriuretic peptide receptor-A in heart failure.[see comment]. [Journal Article] Circulation Research. 99(2):183-90, 2006 Jul 21. UI: 16778132(38)

(38) D'Abaco GM. Ng K. Paradiso L. Godde NJ. Kaye A. Novak U. ADAM22, expressed in normal brain but not in high-grade gliomas, inhibits cellular proliferation via the disintegrin domain. [Journal Article] Neurosurgery. 58(1):179-86; discussion 179-86, 2006 Jan. UI: 16385342

(39) Dietrich Mebs, Ulrich Kuch, Fredy I.V. Coronas, Cesar V.F. Batista, Andreas Gumprecht and Lourival D. Possani: Biochemical and biological activities of the venom of the Chinese pitviper Zhaoermia mangshanensis, with the complete amino acid sequence and phylogenetic analysis of a novel Arg49 phospholipase A2 myotoxin. Toxicon. (vol 42) 2003 Pages 797-811 (venom analysis of this very large "spitting" pit viper of a single mountain in Hunan province,Mt. Mang. "The venom of Zhaoermia exhibits high coagulant activity on bovine and human fibrinogen and human plasma, high phosphodiesterase and arginine ester hydrolytic activity, and moderate to low l-amino acid oxidase, kallikrein, caseinolytic, phospholipase A2 (PLA2), haemorrhagic and myotoxic activities. The approximate i.p. LD50 of the venom in mice was estimated to be 4 mg/kg.")

(40) SITPRIJA, VISITH Snakebite nephropathy (Review Article). Nephrology. 11(5):442-448, October 2006.

(41) Campbell JA, Lamar WW. 2004. The Venomous Reptiles of the Western Hemisphere. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. ISBN 0-8014-4141-2.

(42)Veto, T.; Price, R.; Silsby, J. F.; Carter, J. A.:Treatment of the first known case of king cobra envenomation in the United Kingdom, complicated by severe anaphylaxis. Anaesthesia, Volume 62, Number 1, January 2007, pp. 75-78(4) (We describe the case of a 22-year-old shop worker who was bitten whilst feeding a king cobra in a specialist reptile outlet in Bristol, UK." The man lives.)

(43) Warren W. Wetzel and Nicholas P. Christy: A king cobra bite in New York City • SHORT COMMUNICATION, Toxicon, Volume 27, Issue 3, (1989) Pages 393-395 (a 30 year old "reptile importer" is bit by a 6ft long King Cobra while inspecting his goods at Kennedy Airport. The man lives, the snake is killed.)

(44) Somsri Ganthavorn. A case of king cobra bite . SHORT COMMUNICATION Toxicon 9, Issue 3 (1971) 293-294 . (ase report of an experienced 58 year old snake handler bitten by a "huge" King Cobra while employed at Queen Saovabha Memorial Institute,the scientific Snake Farm of Thailand. Authors say that there have been no documented reports of lethal King Cobra bites in Thailand despite the commonness of the snake because it keeps to remote areas.)

(45) Reid HA. Bites by foreign venomous snakes in Britain. British Medical Journal 1978; 1: 1598–600.

(46) Koh DCI, Armugam A, and Jeyaseelan, Snake venom components and their application in biomedicine. Review. Cellular and Molecular Life Sciences DOI 10.1007/s00018-006-6315-0 copyright Birkhauser Verlag, Basel, 2006

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 224
Total 609
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)

Snake families

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

As far as I can tell, the experts have not yet settled on an infraorder and superfamily for this group of snakes (i.e. Colubroidea, Caenophidia, Xenophidia, Alethinophidia, etc.); I've yet to find two sources that say the same thing. Therefore, I think it'll be better for us not to try to group them together, but simply to mention them as four separate families.

As for the families themselves, there isn't too much disagreement about this today. The pitless vipers and the pit vipers used to be classed in two different families, resp. the Viperidae and the Crotalidae, but have been classed as two subfamilies, the Viperinae and the Crotalinae, under the Viperidae for some time now. (Come to think of it, there are two more Viperidae subfamilies, the Azemiopinae and the Causinae, with a total of seven species that I forgot to add to the totals above!). They have long, hollow, folding fangs that swing forwards and back, while the venom consists mainly of protein-degrading enzymes.

The Elapidae are more problematic. Originally, the cobras, coral snakes, kraits, mambas and Australian elapids were placed in one group, the Elapidae, and the sea snakes in another, the Hydrophiidae. Almost everyone now agrees that they are all related, but so far nobody's been able to convincingly explain the phylogeny of the three major groups -- elapids, sea snakes and Australian elapids. Consequently, many experts either lump the many different genera together in the Elapidae, or describe two or three subfamilies: the Elapinae, the Hydrophiinae and perhaps the Laticaudinae (seakraits). All have relatively short, hollow, fixed fangs, while the venom consists mainly of neurotoxins.

The genera under the Atractaspididae (stiletto snakes, mole vipers) used to be classed as vipers, but are actually quite different. They are completely fossorial, and instead of having fangs that fold back and forth, theirs fold out to the side. Also referred to as side-stabbing snakes, these fangs can become quite large. The venom glands of the genus Atractaspis are very much elongated and resemble those of the elapids, but the venom contains a unique cardiotoxin called sarafotoxin.

The Colubridae are definitely a separate group, but they're also one huge mess. Many are not venomous at all, many have a toxic saliva but no specialized teeth to deliver it, and then there is a group with grooved fangs at the back of the mouth that are mostly listed as mildly venomous, although a few are deadly.

Hope this helps! --Jaap Winius 16:00, 27 December 2006 (CST)

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 remove that boilerplate announcement that the article was originally written from it, it would be helpful.Nancy Sculerati MD

Interesting. Reminds me of something I saw on TV a while back about honey badgers,Mellivora capensis in southern Africa. It showed one attacking a puff adder, Bitis arietans, getting bitten in the face in the process, killing it and then eating it. After that the venom took affect and its face became noticeably swollen. It curled up on the spot and lay like that for a while (a day?), after which it recovered, got up and wandered off as though it was all in a day's work. Maybe this was a similar case of venom resistance. --Jaap Winius 10:28, 27 December 2006 (CST)

Images

I suggest this [1] could be considered

This is the Indian mongoose [2] Gareth Leng 13:16, 27 December 2006 (CST)

Gareth, I love the Indian mongoose picture. The cartoon of the neuromuscular junction is ok, but it would be better if it showed the synaptic vesicles and the ACh receptors. Can you download it and draw them in with Illustrator? ( my motto- always ask for a little more!) Maybe we could get Matt to make an animation!!!!! Nancy Sculerati MD

Jaap, that's very interesting, about the honey badger. I did a first run look for something on that species, but so far - nothing. It's interesting that if the swelling was more than one would expect from just the puncture wounds, that it means it was not a "dry bite". So, yes, it seems like a reasonable hypothesis that this animal also has some kind of resistance. Nancy Sculerati MD

Requesting more images for this article but I do not know much on the topic. Maybe a picture of an example of a container of anti-venom. Any other ideas? A saw a snake hunter guy on discovery the other day and he made the snake bite into a parafilm covered glass beaker to display the venom. Could we show something like that? If you were to put that picture up, put up a disclaimer with it - not to try at home - lol. -Tom Kelly (Talk) 18:38, 30 December 2006 (CST)

Vipers

A few remarks. Regarding envenomation that leads to systemic symptoms, probably the most infamous example is the genus Echis (saw-scaled vipers). It looks like that's where your current description comes from. The venom of Echis carinatus (Indian saw-scaled viper) is also used to make an anticoagulant drug: echistatin.

General terminology:

  • Family Atractaspididae (atractaspidids) -- mole vipers (a.k.a. stilleto snakes).
  • Family Colubridae (colubrids) -- typical snakes.
  • Family Elapidae (elapids) -- cobras, coral snakes, kraits, mambas, Australian elapids, sea snakes, sea kraits.
  • Family Viperidae (viperids) -- pitless vipers, pit vipers.
    • Subfamily Viperinae (viperines) -- pitless vipers
    • Subfamily Crotalinae (crotalines) -- pit vipers (including rattlesnakes).

Often for practical reasons, some authors still split the Elapidae into three subfamilies:

    • Subfamily Elapinae (elapines) -- cobras, coral snakes, kraits, mambas, Australian elapids.
    • Subfamily Hydrophiinae (hydrophiines) -- sea snakes.
    • Subfamily Laticaudinae (laticaudines) -- sea kraits.

Occasionally, you'll see the term "crotalid" or "cortalids". This is an outdated term used to refer to members of the family Crotalidae, which comprised all pit vipers (including the rattlesnakes of Crotalus for which it was named). Later it was reduced to the subfamily listed above.

Remember that there are only two genera of rattlesnakes: Crotalus and Sistrurus. The latter are the massasaugas and pigmy rattlesnakes. Agkistrodon are New World copperheads and moccasins. The largest member of the genus Crotalus is C. adamanteus, the Eastern diamondback. The smallest is C. willardi, the ridge-nosed rattlesnake. The smallest rattlesnake is Sistrurus miliarius, the pygmy rattlesnake. This is according to Klauber (1997).

Besides Echis, some other venoms of major interest (and medical significance) are Daboia russelii (Russell's viper), Bitis arietans (common puff adder), Bothrops atrox (common lancehead) and Bothrops asper (terciopelo).

Some viperid venoms are unusual because they have largely or entirely neurotoxic qualities. Examples are Crotalus durissus (South American rattlesnake, particularly C. d. terrificus), Crotalus scutulatus (Mojave rattlesnake), Bitis atropos (berg adder), and Pseudocerastes persicus fieldi (Field's horned viper). The venoms of Bothrops caribbaeus (Saint Lucia lancehead) and Bothrops lanceolatus (Martinique lancehead) are also interesting, as they are the only ones known to cause thrombosis of major arteries (Campbell & Lamar, 2004).

Some interesting and little-known facts: Bites from C. d. terrificus can result in complete blindness. Usually this is temporary, but it may be permanent. One bite from B. atrox also resulted in complete blindness in less than one minute, lasting for 3-4 minutes. Victims bitten by B. lanceolatus may loose the ability to speak (Campbell & Lamar, 2004). --Jaap Winius 22:08, 29 December 2006 (CST)

Ooops! sorry about the memory mistake for Sistruris, and thanks for the above information, including the classification update. Could you kindly add the complete reference for the Campbell & Lamar, 2004, so that I can find it and read it? Also, please add things right in the article. We can always modify it with discussion. Nancy Sculerati MD 10:33, 30 December 2006 (CST)

Request upload from Wikipedia Commons to Article

Image:Russel's Viper.JPG

There are plenty of D. russelii images over at Wikimedia Commons. They'll all be available just as soon as CZ's admins can manage to locate and install a plugin called InstantCommons. After that the plan is to create a fork of Wikimedia Commons. --Jaap Winius 06:52, 1 January 2007 (CST)
Retrieved from "https://citizendium.org/wiki/index.php?title=Talk:Snake_venom&oldid=11734"