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PubMed2005

A serotonin receptor antagonist, but not melatonin, modulates hormonal responses to capture stress in two populations of garter snakes (Thamnophis sirtalis parietalis and Thamnophis sirtalis concinnus).

Hormonal and behavioral responses to a stressor depend on many factors, including the influence of other hormones. We examined the role of melatonin in modulating hormonal responses to capture stress in two populations of male garter snakes, Thamnophis sirtalis. Studies of red-sided (T. sirtalis parietalis) and red-spotted (T. sirtalis concinnus) garter snakes were conducted in the field with free-living snakes. Populations of red-sided garter snakes in south-central Manitoba, Canada undergo a period of winter dormancy for approximately 8 months each year followed by an attenuated mating season (4-5 weeks) in early spring. In contrast, the mid-latitude red-spotted garter snake in western Oregon, USA has an extended breeding season and can be active during 10-12 months of the year given appropriate environmental conditions. We chose to study these two populations of garter snakes to investigate possible variation in melatonin function among snakes with different suites of environmental adaptations. To better address these questions, we also examined the effects of 5-hydroxytryptophan (a precursor of melatonin synthesis) and ketanserin (a serotonergic type 2A receptor antagonist) on hormonal responses to capture stress. We observed a trend of increased corticosterone and decreased androgen concentrations in northern-latitude red-sided garter snakes (T. sirtalis parietalis) subjected to 4 h of capture stress during the spring. However, these differences were not statistically significant. During the fall, red-sided garter snakes showed no change in corticosterone or androgen concentrations in response to the capture stress treatments. We speculate that northern-latitude red-sided garter snakes suppress hormonal responses to capture stress during preparation for winter dormancy. Treatment with melatonin, 5-hydroxytryptophan, or ketanserin did not significantly influence corticosterone or androgen concentrations of northern-latitude red-sided garter snakes during the spring or fall. Mid-latitude red-spotted garter snakes (T. sirtalis concinnus) from Oregon showed a statistically significant increase in corticosterone concentrations in response to 4 h of capture stress; treatment with melatonin, 5-hydroxytryptophan, or ketanserin prior to capture stress had no significant influence on plasma corticosterone concentrations. Androgen concentrations of mid-latitude red-spotted garter snakes in response to capture stress were significantly lower than those of non-stressed control snakes. Neither melatonin nor 5-hydroxytryptophan influenced the change in androgen concentrations during capture stress. However, androgen concentrations of snakes treated with ketanserin prior to 4 h of capture stress did not differ significantly from those of non-stressed control snakes. These studies suggest that melatonin does not modulate hormonal responses to capture stress in this ectothermic model. Our results also suggest that a serotonin-regulated system may play a role in modulating the activity of the hypothalamic-pituitary-gonadal axis during physiological stress responses.

5-Hydroxytryptophan↗

PubMedDate not supplied

Snake bites in the hills of north India.

BACKGROUND: Snake bites are a common cause of morbidity and mortality in the hills. The risk of snake bite is high due to the presence of a huge herpeto fauna flourishing in a favourable climate--low environmental temperature and heavy rainfall. In India, there are 236 species of snakes of which four are dangerously venomous. This study was undertaken to determine the risk factors exposing the population to snake bite and the common types of snakes causing them. METHODS: We studied 243 patients of snake bite over a period of 24 months. All patients were examined for evidence of snake bite and, where possible, the snakes were identified based on description, identification (if the snake was brought) and symptoms of envenomation. RESULTS: Seasonal variation in snake bite was seen, with a peak in the months of August and September. No bites were recorded in December, January and February. Eighty-four per cent of the bites were on the hands and feet (up to the ankle). Bites on the hand were more common in females with a left hand preponderance (3.5 times higher). The age group most affected was between 11 and 40 years (73.7%). Most bites occurred while the person was cutting grass, working in the fields or walking in the hills (75.3%). Snake bites while sleeping were at uncommon sites. Non-poisonous snakes were the most common (90.5%). Kraits caused 60% of bites with envenomation. CONCLUSION: Snake bites occur frequently in the hills of Himachal Pradesh. Although snake bites are a cause for concern, most of them are caused by non-poisonous snakes.

Adolescent↗

PubMed2002

Snake phylogeny based on osteology, soft anatomy and ecology.

Relationships between the major lineages of snakes are assessed based on a phylogenetic analysis of the most extensive phenotypic data set to date (212 osteological, 48 soft anatomical, and three ecological characters). The marine, limbed Cretaceous snakes Pachyrhachis and Haasiophis emerge as the most primitive snakes: characters proposed to unite them with advanced snakes (macrostomatans) are based on unlikely interpretations of contentious elements or are highly variable within snakes. Other basal snakes include madtsoiids and Dinilysia--both large, presumably non-burrowing forms. The inferred relationships within extant snakes are broadly similar to currently accepted views, with scolecophidians (blindsnakes) being the most basal living forms, followed by anilioids (pipesnakes), booids and booid-like groups, acrochordids (filesnakes), and finally colubroids. Important new conclusions include strong support for the monophyly of large constricting snakes (erycines, boines. pythonines), and moderate support for the non-monophyly of the trophidophiids' (dwarf boas). These phylogenetic results are obtained whether varanoid lizards, or amphisbaenians and dibamids, are assumed to be the nearest relatives (outgroups) of snakes, and whether multistate characters are treated as ordered or unordered. Identification of large marine forms, and large surface-active terrestrial forms, as the most primitive snakes contradicts with the widespread view that snakes arose via minute, burrowing ancestors. Furthermore, these basal fossil snakes all have long flexible jaw elements adapted for ingesting large prey ('macrostomy'), suggesting that large gape was primitive for snakes and secondarily reduced in the most basal living foms (scolecophidians and anilioids) in connection with burrowing. This challenges the widespread view that snake evolution has involved progressive, directional elaboration of the jaw apparatus to feed on larger prey.

Anatomy, Comparative↗

PubMed2000

[Snake as a symbol in medicine and pharmacy - a historical study].

The snake and snake venoms have stimulated the mind and imagination of humankind since the beginning of records about society. No animal has been more worshipped yet more cast out, more loved yet more despised than the snake. The essence of the fascination with fear of the snake lies within the creature's venom. Snakes have been used for worship, magic potions and, medicine, and they have been the symbol of love, health, disease, medicine, pharmacy, immortality, death and even wisdom. In the Sumer civilization (B.C. 2350-2150), designs with 2 snakes appeared. In Greek mythology (B.C. 2000-400), statues of Asclepius (God of Medicine), with "Caduceus" (made of two snakes and a staff), and his daughter Hygeia (God of Health), holding a snake and bowl, were created as symbols for medicine and health, respectively. A kind of Caduceus (1 snake and 1 staff) has been used as a symbol by the World Health Organization (WHO) and a snake and bowl as a symbol of pharmacies in Europe. Snakes have also been worshipped by old Indian peoples involved in Hinduism since 6-4th century B.C. In ancient Egypt, snake designs were used in hieroglyphs. In China, dried bodies of about 30 species of snakes are still using as Chinese medicines. In Japan, a painting of the symbol of "Genbu" (snake with tortoise) was found recently on the north wall of the Takamatsuzuka ancient tomb (7-8th century A.D.), however it is a symbol of a compass direction, and has probably less relation to medicine and pharmacy.

Animals↗

PubMed1975

The effects of snake venoms and their neurotoxins on the nervous system of man and animals.

Myasthenia gravis is a subject of tremendous interest ot neurologists. Snake poisoning, however, which gives rise to a clinical picture resembling a myasthenic crisis, has evoked little interest among neurologists. This state of affairs exists partly because most snake bites occur in areas where physicians, let alone neurologists, are not commonly found. Hence, few neurologists have seen a case of snake bite with nervous system involvement. This is unfortunate, because many of the published cases of snake bite are the poorer for the lack of detailed examination and observations that a neurologist might have provided. Not only is the clinical picture of snake envenomation a fascinating one where the neurologist, haematologist, cardiologist, and renal physician can find a common clinical interest, but an understanding of the way in which snake venoms act on the nervous system is of importance to the neurologist since the neurotoxic snake venoms act principally at the neuromuscular junction. They produce a flaccid paralysis of the voluntary muscles and cause death from respiratory obstruction and/or respiratory insufficiency. Like the purified defibrinating fraction("Arvin") of the venom of the Malayan pit viper (Agkistrodon rehodostoma), which is currently being used and evaluated as an anticoagulant, the thereapeutic possibilities of a purified neurotoxin that could produce a flaccid paralysis lasting two days or more were anticipated well before 1891 by Lauterer, who, as a result of his experiments, "injected viper poison...under the skin of a boy suffering from tentanus treaumaticus (lockjaw) and slackened the muscles of the whole body by it." This chapter will initially describe the clinical picture of nervous system involvement in snake bite, with particular emphasis on Australian snake bite. The description will be based on observations made at the Port Moresby General Hospital over a period of seven years on 56 patients with paralysis following snake bite, and on some published cases of Australian snake bite. The discussion will then cover some of the recent published work on the action of snake venoms on the nervous system, dealing mainly with elapid venoms. There are several recent reviews describing the toxic properties and actions of all types of snake venoms.

Animals↗

PubMed2002

Extremely low nerve growth facior (NGF) activity of sea snake (Hydrophiidae) venoms.

Sea snake venoms contain less protein than those of land snakes (Toom et al., 1969). Sea snake venoms lack arginine ester hydrolyzing activity, whereas those of Crotalidae and Viperidae have such activity (Tu et al., 1966). Sea snakes live in salty water, and their venoms may be different from those of land snakes. Because of the difficulty in obtaining sea snake venoms, information about sea snake venoms is quite incomplete. NGF is commonly present in the venoms of land snakes such as Elapidae, Viperidae, and Crotalidae (Cohen and Levi-Montalcini, 1956; Lipps, 2002). It is therefore of interest to investigate the presence or absence of NGF in sea snake venoms. In order to investigate the presence or absence of NGF, five sea snake venoms were selected. Lapemis hardwickii (Hardwick's sea snake) and Acalyptophis peronii venom were obtained from the Gulf of Thailand. Hydrophis cyanocinctus (common sea snake) and Enhydrina schistosa (beaked sea snake) venom were obtained from the Strait of Malacca. Laticauda semifasciata (broad band blue sea snake) venom was also examined and the venom was obtained from Gato Island in the Philippines.

Animals↗

PubMed2006

Snakes as agents of evolutionary change in primate brains.

Current hypotheses that use visually guided reaching and grasping to explain orbital convergence, visual specialization, and brain expansion in primates are open to question now that neurological evidence reveals no correlation between orbital convergence and the visual pathway in the brain that is associated with reaching and grasping. An alternative hypothesis proposed here posits that snakes were ultimately responsible for these defining primate characteristics. Snakes have a long, shared evolutionary existence with crown-group placental mammals and were likely to have been their first predators. Mammals are conservative in the structures of the brain that are involved in vigilance, fear, and learning and memory associated with fearful stimuli, e.g., predators. Some of these areas have expanded in primates and are more strongly connected to visual systems. However, primates vary in the extent of brain expansion. This variation is coincident with variation in evolutionary co-existence with the more recently evolved venomous snakes. Malagasy prosimians have never co-existed with venomous snakes, New World monkeys (platyrrhines) have had interrupted co-existence with venomous snakes, and Old World monkeys and apes (catarrhines) have had continuous co-existence with venomous snakes. The koniocellular visual pathway, arising from the retina and connecting to the lateral geniculate nucleus, the superior colliculus, and the pulvinar, has expanded along with the parvocellular pathway, a visual pathway that is involved with color and object recognition. I suggest that expansion of these pathways co-occurred, with the koniocellular pathway being crucially involved (among other tasks) in pre-attentional visual detection of fearful stimuli, including snakes, and the parvocellular pathway being involved (among other tasks) in protecting the brain from increasingly greater metabolic demands to evolve the neural capacity to detect such stimuli quickly. A diet that included fruits or nectar (though not to the exclusion of arthropods), which provided sugars as a neuroprotectant, may have been a required preadaptation for the expansion of such metabolically active brains. Taxonomic differences in evolutionary exposure to venomous snakes are associated with similar taxonomic differences in rates of evolution in cytochrome oxidase genes and in the metabolic activity of cytochrome oxidase proteins in at least some visual areas in the brains of primates. Raptors that specialize in eating snakes have larger eyes and greater binocularity than more generalized raptors, and provide non-mammalian models for snakes as a selective pressure on primate visual systems. These models, along with evidence from paleobiogeography, neuroscience, ecology, behavior, and immunology, suggest that the evolutionary arms race begun by constrictors early in mammalian evolution continued with venomous snakes. Whereas other mammals responded by evolving physiological resistance to snake venoms, anthropoids responded by enhancing their ability to detect snakes visually before the strike.

Animals↗

PubMedDate not supplied

Management of snake-bite in rural Maharashtra: a 10-year experience.

BACKGROUND: A high incidence of snake-bite envenomation has been reported from Marathwada, Maharashtra. This study analysed the pattern of snake-bites and their management in a rural area of India over a 10-year period. METHODS: A total of 633 patients with snake-bite admitted to the Rural Community Centre and Punde Hospital in Mukhed taluka, Nanded district (Marathwada) of Maharashtra, between 1992 and 2001, were analysed retrospectively. The local and systemic manifestations of snake-bite, response to antisnake venom, atropine and neostigmine, the treatment of complications and the outcome were analysed. RESULTS: Of the 633 patients, 427 (67.5%) had been bitten by poisonous snakes and 206 (32.5%) by non-poisonous snakes. The majority of snake-bites (68.9%) occurred between May and November. Those affected were mainly farmers (228 [36%]), students (191 [30.2%]) and housewives (175 [27.6%]). Of the 427 envenomed by poisonous snakes, 274 (64.2%) were by Echis carinatus (saw-scaled viper), 71 (16.6%) by cobra, 42 (9.8%) by krait and 40 (9.4%) by Russell viper. The requirement of antisnake venom for treating neurotoxic envenomation was 40-320 ml and for Echiscarinatus and Russell viper bites it was 20-250 ml. Among those envenomed by poisonous snakes, the mortality was 4.7% (n=20). CONCLUSION: Snake-bite is a common life-threatening emergency in the study area. We observed an occupational risk and a seasonal incidence of snake-bite. Knowledge of the varied clinical manifestations of snake-bite are important for effective management. Ready availability and appropriate use of antisnake venom, close monitoring of patients, institution of ventilatory support and early referral to a larger hospital when required help in reducing the mortality. Most patients with snake-bites can be successfully managed even in small rural hospitals with limited facilities.

Adult↗

PubMed2004

Feeding behavior and venom toxicity of coral snake Micrurus nigrocinctus (Serpentes: Elapidae) on its natural prey in captivity.

The feeding behavior and venom toxicity of the coral snake Micrurus nigrocinctus (Serpentes: Elapidae) on its natural prey in captivity were investigated. Coral snakes searched for their prey (the colubrid snake Geophis godmani) in the cages. Once their preys were located, coral snakes stroke them with a rapid forward movement, biting predominantly in the anterior region of the body. In order to assess the role of venom in prey restraint and ingestion, a group of coral snakes was 'milked' in order to drastically reduce the venom content in their glands. Significant differences were observed between snakes with venom, i.e., 'nonmilked' snakes, and 'milked' snakes regarding their behavior after the bite. The former remained hold to the prey until paralysis was achieved, whereas the latter, in the absence of paralysis, moved their head towards the head of the prey and bit the skull to achieve prey immobilization by mechanical means. There were no significant differences in the time of ingestion between these two groups of coral snakes. Susceptibility to the lethal effect of coral snake venom greatly differed in four colubrid species; G. godmani showed the highest susceptibility, followed by Geophis brachycephalus, whereas Ninia psephota and Ninia maculata were highly resistant to this venom. In addition, the blood serum of N. maculata, but not that of G. brachycephalus, prolonged the time of death of mice injected with 2 LD(50)s of M. nigrocinctus venom, when venom and blood serum were incubated before testing. Subcutaneous injection of coral snake venom in G. godmani induced neurotoxicity and myotoxicity, without causing hemorrhage and without affecting heart and lungs. It is concluded that (a) M. nigrocinctus venom plays a role in prey immobilization, (b) venom induces neurotoxic and myotoxic effects in colubrid snakes which comprise part of their natural prey, and (c) some colubrid snakes of the genus Ninia present a conspicuous resistance to the toxic action of M. nigrocinctus venom.

Animals↗

PubMed2004

The in vitro neuromuscular activity of Indo-Pacific sea-snake venoms: efficacy of two commercially available antivenoms.

We examined the neurotoxicity of the following sea snake venoms: Enhydrina schistosa (geographical variants from Weipa and Malaysia), Lapemis curtus (Weipa and Malaysia), Laticauda colubrina, Aipysurus laevis, Aipysurus fuscus and Aipysurus foliosquamatus. Venom from a terrestrial snake, Notechis scutatus (tiger snake), was used as a reference. All venoms (1 and 3 microg/ml) abolished indirect twitches of the chick biventer cervicis muscle and significantly inhibited responses to ACh (1 mM) and CCh (20 microM), but not KCl (40 mM), indicating the presence of post-synaptic toxins. Prior administration (10 min) of CSL sea snake antivenom (1 unit/ml) attenuated the twitch blockade produced by N. scutatus venom and all sea snake venoms (1 microg/ml). Prior administration (10 min) of CSL tiger snake antivenom (1 unit/ml) attenuated the twitch blockade of all venoms except those produced by E. schistosa (Malaysia and Weipa) and A. foliosquamatus. Administration of CSL sea snake antivenom (1 unit/ml) at t90 (i.e. time at which 90% inhibition of initial twitch height occurred) reversed the inhibition of twitches (20-50%) produced by the sea snake venoms (1 microg/ml) but not by N. scutatus venom (1 microg/ml). CSL tiger snake antivenom (1 unit/ml) administered at t90 produced only minor reversal (i.e. 15-25%) of the twitch blockade caused by L. curtus (Weipa), A. foliosquamatus, L. colubrina and A. laevis venoms (1 microg/ml). Differences in the rate of reversal of the neurotoxicity produced by the two geographical variants of E. schistosa venom, after addition of CSL sea snake antivenom, indicate possible differences in venom components. This study shows that sea snake venoms contain potent post-synaptic activity that, despite the significant genetic distances between the lineages, can be neutralised with CSL sea snake antivenom. However, the effects of CSL tiger snake antivenom are more variable.

Animals↗

PubMed2002

Helminth infracommunity structure of the sympatric garter snakes Thamnophis eques and Thamnophis melanogaster from the Mesa Central of Mexico.

Seventy-two Mexican garter snakes (Thamnophis eques) and 126 black-bellied garter snakes (T. melanogaster) were collected from 4 localities of the Mesa Central of Mexico between July 1996 and February 1998 and examined for helminths. Both species of garter snakes occurred sympatrically in every locality except in Lake Cuitzeo. Both species of snakes shared 9 helminth species, and in general, T. melanogaster hosted a larger number of species than T. eques. In each locality, a different helminth species showed the highest levels of prevalence and abundance (Spiroxys susanae in Ciénaga de Lerma, Telorchis corti in Lago de Pátzcuaro, Proteocephalus variabilis in Lago de Cuitzeo, and Contracaecum sp. in Lago de Chapala). Helminth communities in garter snakes of the Mesa Central are depauperate and dominated by a single parasite species. In those localities where the snakes occurred in sympatry, helminth communities were, in general, more diverse and species-rich in T. melanogaster. Differences in the ecology and physiology of these species of garter snakes may explain this pattern because black-bellied garter snakes (T. melanogaster) are more aquatic than Mexican garter snakes (T. eques) and primarily eat aquatic prey, potentially exposing themselves to a larger number of helminths transmitted by predator-prey infection. The helminth infracommunities of garter snakes in the Mesa Central of Mexico show a strong Nearctic influence because most of the species infecting these hosts have been recorded in other Nearctic colubrid snakes. However, the helminth infracommunities of these garter snakes are less species-rich and less diverse than those in colubrid snakes in more temperate latitudes. The widespread ecological perturbation of sampling sites in the Mesa Central because of human activity, and geographic differences in foraging ecology of the hosts and, thus, exposure to parasites transmitted by intermediate hosts may help to explain these patterns.

Animals↗

PubMed2005

Snake envenomation in dogs in New South Wales.

OBJECTIVE: To obtain baseline data on the prevalence of elapid snake envenomation in dogs presented to veterinary practices in New South Wales and to assess attitudes of veterinarians to this clinical entity. PROCEDURE: A mailed questionnaire, sent to all veterinary clinics within New South Wales, was utilised to collect epidemiological information regarding elapid snake envenomation in dogs. RESULTS: A response rate of 68% was obtained and a yearly prevalence of snake envenomation in dogs across New South Wales veterinary clinics was estimated as 0.31%. The most common species reported to be responsible for envenomation within NSW was the Red Bellied Black snake (Pseudechis porphyriacus) followed by the Brown snake (Pseudonaja textilis) and then Tiger snake (Notechis scutatus). The reported envenomation syndromes caused by these common snake species were perceived to be similar for Brown and Tiger snakes but differed for Red Bellied Black snakes. Diagnosis of snake envenomation was based predominantly on the recognition of clinical signs. Specific diagnostic tests, such as venom detection kits, were used infrequently. The most common treatment was reported to be a combination of intravenous fluid therapy and antivenom, and monitoring of response to this treatment was usually through assessment of clinical signs. Survival after antivenom administration was reported to be highest for Red Bellied Black snake species. Survival was perceived to be associated with time between envenomation and presentation to the veterinary clinic and with antivenom administration. CONCLUSIONS: Current attitudes and perceptions of veterinarians have been defined. Diagnosis of species-specific snake envenomation is shown to be made on the basis of clinical signs which are, however, reported as similar for each species. Clearer definition of these envenomation syndromes and identification of accessible diagnostic testing procedures are needed.

Animals↗

PubMed2006

Physiological and hormonal control of thermal depression in the tiger snake, Notechis scutatus.

Plasma sodium concentrations in field-caught Western tiger snakes, Notechis scutatus, from semi-arid Carnac Island (CI) varied seasonally, with snakes exhibiting significant hypernatraemia during summer and normal concentrations following autumn rain. In contrast, field-caught tiger snakes from a perennial fresh-water swamp (Herdsman Lake, HL) exhibited no significant increase in plasma sodium concentrations during summer. Laboratory-induced hypernatraemia caused thermal depression in both populations; there was a weak negative relationship between plasma sodium concentration and temperature selection that was significant for CI snakes. Hypernatraemia significantly elevated circulating concentrations of the neuropeptide arginine vasotocin (AVT) in both CI and HL snakes. CI snakes injected with a physiological dosage of AVT also evidenced thermal depression. Despite the positive correlation between AVT and both plasma sodium concentration and osmolality for laboratory snakes, field samples from CI snakes indicate that circulating levels of AVT may be influenced more by plasma osmolality than sodium levels. The data suggest that, in CI snakes, chronic dehydration in the field leads to hypernatraemia which may lead to elevated levels of AVT if plasma osmolality also increases. This will in turn invoke a depression in thermal behaviour that may improve the water economy and survival of snakes on semi-arid CI. Although HL snakes do not experience seasonal dehydration, physiological changes away from the stable homeostatic state appear to prompt the same behavioural shifts, illustrating the intrinsic nature of the thermal behaviour in different populations of the same species of snake.

Animals↗

PubMedDate not supplied

Admissions for suspected snake bite to the Perth adult teaching hospitals, 1979 to 1988.

OBJECTIVE: To describe the epidemiology of snake bite in Perth, and the likelihood of envenomation. DESIGN: Information from case notes was retrospectively analysed. SETTING: Emergency medicine, teaching hospitals. PATIENTS: All patients admitted to the three adult teaching hospitals in Perth for suspected snake bite from 1979 to 1988. MAIN OUTCOME MEASURE: Systemic envenomation, was accepted as present if there were definite symptoms, signs or laboratory evidence (vomiting, abdominal pain, ptosis, convulsions, difficulty with breathing or swallowing, coagulopathy, haemolysis, rhabdomyolysis or renal failure). RESULTS: Ninety-nine patients were definitely bitten, with 53 envenomed, including three snake handlers. Thirty others may have been envenomed. Nearly half (44%) of the 82 patients with witnessed snake bite were envenomed. The dugite (Pseudonaja affinis) caused most cases of envenomation, most often producing coagulopathy only. The remainder were probably due to bites by the tiger snake (Notechis after occidentalis) and gwardar (Pseudonaja nuchalis), with one by a sea snake. The Commonwealth Serum Laboratories Snake Venom Detection Kit (VDK) enabled identification of the genus in 36% of definite cases of snake bite, and in 51% of cases of envenomation. It may occasionally produce false-positive results. The VDK is of greatest value in establishing the genus of snake in envenomed patients. CONCLUSIONS: It is suggested that a mixture of brown and tiger snake antivenom be used to treat patients envenomed by an unidentified snake in the Perth metropolitan area. This does not apply to patients bitten elsewhere in Western Australia or transferred to Perth from country regions where other snakes are more prevalent.

Adolescent↗

PubMedDate not supplied

Deaths from snake bite in Australia, 1981-1991.

OBJECTIVE: To obtain and analyse data relating to snake bite fatalities in Australia. DESIGN: Retrospective analysis of case reports and collation of studies carried out at the Commonwealth Serum Laboratories (CSL). RESULTS: 18 deaths attributed to snake bite were reported to CSL over a 10-year period. Eleven of the victims were males and four of these were bitten after either picking up the snake or playing with it. In most cases, no pathological findings of significance were found at autopsy. Venom was detected in post-mortem samples from nine cases. Brown snakes (genus Pseudonaja) were responsible for 11 deaths; tiger snake (Notechus scutatus) for four, taipan (Oxyuranus scutellatus) two and death adder (Acanthophis australis) one. Death after a brown snake bite was often sudden and unexpected. In three patients bitten by tiger snakes and in one bitten by a brown snake, the presence of cerebral haemorrhage was confirmed at autopsy. CONCLUSIONS: Not all snake bite deaths in Australia are adequately investigated or reported. Under some circumstances death from snake bite is almost inevitable; two infants who received unwitnessed massive envenomations are tragic examples. Had venom absorption from the bitten area been delayed by correct first aid, some of the patients might have survived. The brown snakes (genus Pseudonaja) must now be considered Australia's most dangerous group of snakes because their venom may cause sudden unexpected collapse and death. The increased incidence of intracranial haemorrhage may in some cases be related to the intravenous use of adrenaline. In at least one case, the prompt administration of a clearly needed antivenom might have altered the outcome.

Adolescent↗

PubMed1975

Epidemiology of sea-snake bites.

Epidemiological features as reflected by 101 patients with unequivocal sea-snake bite received in north-west Malaya are reviewed. Enhydrina schistosa caused over half the bites, including seven of the eight fatal bites. It is the most dangerous sea-snake to man. Over 90 per cent of the victims were male and 80 of the 101 patients were fishermen bitten at their job. Most victims were bitten on the lower limb through treading on the snake, and this resulted in more cases of serious poisoning than upper limb bites (caused through handling nets, sorting fish and so on). Only 14 cathers were bitten (through treading on the sea-snake; no bathers were bitten while swimming). In patients coming to hospital more than six hours after the bite, there was a four-fold increase in serious poisoning compared with patients coming within six hours of the bite. Thus, as time elapses after the bite, the victim is less likely to seek medical help unless poisoning is severe. Despite the lethal toxicity of sea-snake venom, in patients seen during 1957-61 before sea-snake antivenom became available, the mortality was only 10 per cent. Trivial or no poisoning followed in 80 per cent of the bites. On the other hand, of 11 patients (20 per cent) with serious poisoning, over half (six patients) died despite supportive hospital treatment. These epidemiological features observed in Malaya probably apply to most fishing folk along Asian coastlines where sea-snakes abound. If this is so, sea-snake bite must be a common hazard feared by millions of fishing folk, and a common cause of illness and death. But it is unlikely that the extent of this problem will be revealed to orthodox medicine for many decades because most fishing villages are far from medical centres; and even if hospitals or medical centres are available, fishing folk are usually reluctant to attend them. Only one species of sea-snake, Pelamis platurus, extends to the east coasts of Africa and west coasts of the tropical Americas, but for various reasons this species does not appear to constitute much of a hazard to fishing folk in these areas. Although bathers are occasionally bitten along Asian coasts, when they inadvertently tread on a sea-snake, the risk of sea-snake bite in this area is extremely low. The prevention of sea-snake bite and poisoning is considered. Highly effective antivenom is now available for treating victims with serious poisoning; death should not occur provided adequate medical treatment is given within a few hours of the bite. The main problem is provision of adequate medical care at rural medical centres and overcoming the reluctance fishing folk often have in attending these centres.

Adolescent↗

PubMed2006

Becoming airborne without legs: the kinematics of take-off in a flying snake, Chrysopelea paradisi.

Among terrestrial vertebrate gliders, take-off presents a unique problem to flying snakes (Chrysopelea). Without legs, snakes must use fundamentally different kinematics to begin their aerial trajectories. To determine the effectiveness of different modes of take-off in a gliding snake (C. paradisi), I videotaped multiple views of take-off from a horizontal branch and quantified the two- and three-dimensional coordinates of three points on the snake's body. Performance values derived from these coordinates were used to describe take-off in C. paradisi, compare modes of take-off, and make predictions about the ecological use of take-off in the wild. Four types of take-off were identified. In most observed take-offs, snakes used a vertically looped take-off (termed 'anchored J-loop' and 'sliding J-loop'), which represent the only true jumping in snakes. In an anchored J-loop take-off, the snake formed an anterior hanging loop and then jumped by holding the posterior body static on the branch and accelerating up and away from the branch. This was the most commonly used take-off mode. A sliding J-loop take-off was similar but occurred with the entire body in motion. Snakes using such take-offs lowered less of their body below the branch than in an anchored J-loop take-off, resulting in shorter preparation and vertical acceleration durations and producing a lower maximum vertical velocity. However, these differences did not produce significant differences after the snakes were fully airborne and had started their aerial trajectories. The non-looped take-offs (termed ;dive' and ;fall') were the least kinematically complex. Compared to the non-looped take-offs, looped take-offs allowed snakes to reach higher, range farther, and attain greater speeds. Futhermore, snakes that launched with looped take-offs traveled farther over the course of a full glide trajectory when starting from a 10 m high perch. Take-off in C. paradisi is qualitatively similar to that in other species of Chrysopelea and may represent a suite of behaviors that preceded the evolution of gliding flight in snakes.

Analysis of Variance↗

PubMed1976

Snakes as indicators of environmental contamination: relation of detoxifying enzymes and pesticide residues to species occurrence in three aquatic ecosystems.

Pesticide detoxifying enzymes and residues of p,p'-DDE and PCB were measured in snakes of two genera collected in three aquatic ecosystems in central Texas. Snake genera were Agkistrodon (water moccasins and copperheads) and Natrix (water snakes). One collecting site had heavy exposure to insecticides, one to PCBs and one to neither. Objectives were to correlate pesticide residues and detoxifying enzymes with species occurrence in different ecosystems, to evaluate the usefulness of snakes as indicators of environmental contamination, and to establish a biochemical basis for the differential distribution of snakes between ecosystems. Agkistrodon spp. had several times the NADPH-dependent oxidative detoxifying activity of Natrix spp. Within Natrix, oxidase activity was significantly higher in erythrogaster and fasciata than in rhombifera. Alkyltransferase activity was higher in A. piscivorus (water moccasins) than in any other species. There were no consistent differences between sexes in levels of detoxifying enzymes and enzyme activity was similar in snakes of each species from all collecting sites, indicating no induction had occurred as a result of heavy exposure to insecticides or PCBs. DDE residues were highest in snakes collected adjacent to a cotton agro-ecosystem. PCB residues occurred only in snakes collected near a heavily-traveled highway. Residues in A. piscivorus were only half those in Natrix spp. from the same site, indicating the former is more efficient as disposing of residues. The data indicate that snakes with high levels of detoxifying enzymes, particularly microsomal oxidases, are more likely to occur in a contaminated ecosystem than snakes with less active detoxifying enzymes and that residues are lower in the better detoxifiers. Snakes are apparently excellent indicators of environmental contaminated by insecticides and other persistent chemicals.

Adipose Tissue↗