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Human envenomation from the bite of an aglyphous false coral snake, Pliocercus elapoides (Serpentes : Colubridae)
roxican, Vol. 18, pp . 399-401 . © Pergamon Press Ltd. 1980. Printed in England .
11041-0107/8010510-0399$02 .0010
HUMAN ENVENOMATION FROM THE BITE OF AN AGLYPHOUS FALSE CORAL SNAKE, PLIOCERCUS ELAPOIDES (SERPENTES : COLUBRIDAE) ROBERT L. SEIB Museum of Vertebrate Zoology, University of California, Berkeley, California 94720, U .S.A . (Acceptedfor publication 11 December 1979) A FEW of the numerous, so-called harmless snakes of the family Colubridae are known to be potentially lethal to man, including Dispholidus typus, Thelotornis kirtlandi and Rhabdophis tigrinus ((MINTON and MEBS, 1978 ; MITTLEMAN and GORIS, 1974) . Several other colubrids are capable of human envenomation, producing at least transitory pain but little, if any permanent damage (WELLMAN, 1963 ; KROLL, 1976 ; NICKERSON and HENDERSON, 1976 ; MCKINSTRY, 1978 ; MINTON, 1978) . To this list can now be added the false coral snake, Pliocercus elapoides, a small (maximum body length ca . 340 mm), relatively rare, leaf litter inhabitant of the tropical lowlands of Mexico and northern Central America . I have caught, handled and killed by i .p . injection of Nembutal 56 individuals of this characteristically docile species without being bitten . I am 23 yr old, Caucasian, male, 1-87 m tall, 75 kg in weight, and have had no previous reactions to colubrid bites and no known allergy other than to the poison oak plant. At 17 :00 hr on 18 June 1979 I was injecting a Pliocercus (ca . 200 mm body length) while holding it in my left hand . With jaws opened to nearly 180° , the snake promptly forced its mouth onto the base of the left index finger. Rotating its head once in either direction, it quickly removed its mouth and began to close it . Contact with the finger lasted not more than one second . The moment contact was effected, I experienced a searing pain . I dropped the snake and searched for punture marks which could not be found ; the wound could not be induced to bleed . I then made four superficial longitudinal incisions with the blade of a new Cutter snakebite kit and applied a constriction band above the wrist, maintaining it for 1 hr . Blood flowed freely from the incisions for several min with the aid of a suction device provided in the kit . The finger began to swell within 3 min, and within 10 min the rest of the hand was somewhat swollen . The immediate post-bite pain was not burning, but rather a mild ache . TABLE 1 . VITAL SIGNS FOR PERIOD FOLLOWING ENVENOMATION BY
Hr/date (1979) 13 :30 16 (At rest) 23 :00 18 9 :00 19 16 :00 19 20 :00 19 9 :00 20
Nov
Pliocercus elapoides Blood Respiration Pressure Pulse (min-9 130/78 64 14
Temp (°C) 36-7
June June June June June
140/120 130/110 120/90 120/80 100/70
38-0 37-5 37-0 37-0 36-0
90 80 80 80 70 399
24 22 20 20 20
400
Short Communications
By 18 :00 hr the entire left hand was swollen, the major dorsal surface vessels of the left arm ached, and the axillary lymph nodes were tender and swollen. At this time a deep, local pain was felt in the bitten phalanx of the index finger . Pain came in waves lasting 2 min, with 1 min of respite. Each wave began slowly, becoming nearly intolerable after 45 sec and abruptly terminating in another 75 sec. There was no feeling in the phalanx for the next 60 sec. Shortly after 18 :00 hr I was administered Valium and various pain killers by the Red Cross in Tapachula, Chiapas, M6xico . By 23 :00 hr pain continued as before and the hand appeared ecchymotic on the dorsal aspect. There were no indications of abnormal bleeding, bloody saliva, blood in urine, or prolonged bleeding from the first aid incisions. I was then admitted to a hospital where I received one vial of antivenine for Crotalus through i.m. injection in the right hip (type of serum not disclosed), cortisone, Valium, painkillers and other undetermined drugs. The next morning the finger, hand and arm ached, but pain was mild in contrast to the previous night. Swelling dissipated and color was nearly normal by 21 June. On the morning of 23 June the skin of the hand was nearly black, and remained so for 24 hr ; the skin began to dessicate at this time, appearing ashy and flaky, but returned to normal after another 15 days. I experienced a painful ache and parasthesia in the index finger and vessels of the left arm which awakened me each night until 9 July. Sensitivity began to return slowly to the numb finger and surrounding tissues by 10 July, and the hand appeared fully recovered by 31 July. I never experienced nausea or tingling other than that described. Table 1 lists some vital signs for the post bite period, courtesy of Hospital General B, Carmen de Acebo, Chiapas, M6xico . The top row, taken at rest, is presented for comparison. Abnormally high post-bite figures might be due to shock, ingestion of drugs and/or systemic effects of the venom. The toxic nature of Pliocercus saliva is consistent with SAVITSKY's (1978 : p. 317, Ph . D. diss., Univ . of Kansas) view that the venom of colubrid snakes is an element of a feeding strategy that is an alternative to constriction . During 12 laboratory feedings by two Pliocercus, I never observed these snakes to employ constriction . Salamanders and frogs were subdued and swallowed while the anterior portion of the snakes's body was held relatively straight ; prey were occasionally pinned against the wall or pressed against the substrate with the posterior part of the body while the snake's tail grasped another object for steadiness . Venom delivery systems of snakes need not be elaborate, and enlarged, grooved maxillary teeth are evidently non-essential (e.g., Rhabdophis is aglyphous) . TAUB (1967) conducted a histological investigation of the salivary glands of 180 species of colubrid snakes and found 163 of them to possess a Duvernoy's gland, considered homologous with the venom glands offront-fanged snakes (SAVITSKY, 1978 : p. 311, Ph . D. diss ., Univ. of Kansas). TAUB did not include Pliocercus in his survey, although it possesses enlarged, ungrooved rear maxillary teeth and a Duvernoy's gland (GREENE, personal communication) . MYERS (1974) believes that probably all species of Rhadinaea and the related genus Coniophanes may be venomous ; he considers Pliocercus to be a direct offshoot of the lateristriga species group of Rhadinaea. It is therefore not surprising that Pliocercus is also venomous, in light of this close phylogenetic relationship . Many colubrids probably have at least the potential to inflict a toxic bite. MINTON (1978) states that "with the exception of the boomslang, colubrids must hold on an appreciable time (several seconds) in order to inject venom," and ". . . that a quick defensive bite would not result in envenomation ." Pliocercus is an exception, and there may be others . The name "false coral snake" derives from an uncanny resemblance of Pliocercus to coral snakes, Micrurus, which it precisely parallels in pattern and coloration wherever
Short Communications
40 1
sympatric (GREENE and MCDIARMID, ms .) . Due to the deadly nature of Micrurus venom, Pliocercus has been thought a "presumptive Batesian mimic" of the coral snakes (HECHT and MARIEN, 1956 ; MERTENS, 1956 ; POUCH, 1964 ; GREENE, 1976). My observations show that Pliocercus can produce painful symptoms and, indeed, a single, rapid defensive bite is sufficient for a predator (including man) to learn to avoid such a snake . Pliocercus is best considered a mildly venomous Batesian or Mullerian model, and Micrurus probably contributes to the mimetic relationship in some undetermined capacity . Acknowledgements-1 am indebted to DIETER ENKERLIN, Director, Graduate School in Agriculture, lnstituto Tecnolbgico de Monterrey, Mbxico, and JACK REYNOLDS for their assistance after I was bitten . STEPHEN BUsACK, HARRY GREENE, SHERMAN MINTON, DONALD STRANEY and DAVID WAKE provided helpful criticism of the manuscript . Field work was supported by a grant from the Alexander Fund, Museum of Vertebrate Zoology, University of California, Berkeley . REFERENCES GREENE, H . W . (1976) Coral snake mimicry : does it occur? Herp. Rev. 7, 85 . HECHT, M . K . and D . MARIEN (1956) The coral snake mimicry problem : a reinterpretation . J. Morph . 98, 335 . KROLL, J . C . (1976) Feeding adaptations of hognose snakes . S West Nat. 20, 537. McKiNsTRY, D . M . (1978) Evidence of toxic saliva in some colubrid snakes of the United States . Toxicon 16,523 . MERTENS, R . (1956) Das Problem der Mimikry bei Korallenschlangen . Zool. Jb. (Syst.) 84, 541 . MINTON, S . A . (1978) Beware : nonpoisonous snakes . Nat . Hist. 87(9), 56. MINTON, S . A . and D . MESS (1978) Vier Bissfalle durch Colubriden . Salamandra 14, 41 . MITTLEMAN, M . B. and R . C . GoRis (1974) Envenomation from the bite of the Japanese colubrid snake Rhabdophis tigrinus (Boie). Herpetologica 30, 113 . MYERS, C. W. (1974) The systematics of Rhadinaea (Colubridae), a genus of new world snakes . Bull. Amer . Mus . nat . Hist . 153, 1 . NICKERSON, M . A . and R . W. HENDERSON (1976) A case of envenomation by the South American colubrid, Philodryas oljersi. Herpetologica 32, 197 . DOUGH, F . H . (1964) A coral snake "mimic" eaten by a bird . Copeia 1964, 223 . TAUB, A . M . (1967) Comparative histological studies on Duvernoy's gland of colubrid snakes . Bull. Amer. Mus. nat . Hist . 138, 1 . WELLMAN, J . (1963) A revision of snakes of the genus Coiwphis (family Colubridae, from middle America) . Univ. Kans. Pubis. Mus . nat . Hist . 15, 251 .
Tux . 18/3-u
11041-0107/8010510-0399$02 .0010
HUMAN ENVENOMATION FROM THE BITE OF AN AGLYPHOUS FALSE CORAL SNAKE, PLIOCERCUS ELAPOIDES (SERPENTES : COLUBRIDAE) ROBERT L. SEIB Museum of Vertebrate Zoology, University of California, Berkeley, California 94720, U .S.A . (Acceptedfor publication 11 December 1979) A FEW of the numerous, so-called harmless snakes of the family Colubridae are known to be potentially lethal to man, including Dispholidus typus, Thelotornis kirtlandi and Rhabdophis tigrinus ((MINTON and MEBS, 1978 ; MITTLEMAN and GORIS, 1974) . Several other colubrids are capable of human envenomation, producing at least transitory pain but little, if any permanent damage (WELLMAN, 1963 ; KROLL, 1976 ; NICKERSON and HENDERSON, 1976 ; MCKINSTRY, 1978 ; MINTON, 1978) . To this list can now be added the false coral snake, Pliocercus elapoides, a small (maximum body length ca . 340 mm), relatively rare, leaf litter inhabitant of the tropical lowlands of Mexico and northern Central America . I have caught, handled and killed by i .p . injection of Nembutal 56 individuals of this characteristically docile species without being bitten . I am 23 yr old, Caucasian, male, 1-87 m tall, 75 kg in weight, and have had no previous reactions to colubrid bites and no known allergy other than to the poison oak plant. At 17 :00 hr on 18 June 1979 I was injecting a Pliocercus (ca . 200 mm body length) while holding it in my left hand . With jaws opened to nearly 180° , the snake promptly forced its mouth onto the base of the left index finger. Rotating its head once in either direction, it quickly removed its mouth and began to close it . Contact with the finger lasted not more than one second . The moment contact was effected, I experienced a searing pain . I dropped the snake and searched for punture marks which could not be found ; the wound could not be induced to bleed . I then made four superficial longitudinal incisions with the blade of a new Cutter snakebite kit and applied a constriction band above the wrist, maintaining it for 1 hr . Blood flowed freely from the incisions for several min with the aid of a suction device provided in the kit . The finger began to swell within 3 min, and within 10 min the rest of the hand was somewhat swollen . The immediate post-bite pain was not burning, but rather a mild ache . TABLE 1 . VITAL SIGNS FOR PERIOD FOLLOWING ENVENOMATION BY
Hr/date (1979) 13 :30 16 (At rest) 23 :00 18 9 :00 19 16 :00 19 20 :00 19 9 :00 20
Nov
Pliocercus elapoides Blood Respiration Pressure Pulse (min-9 130/78 64 14
Temp (°C) 36-7
June June June June June
140/120 130/110 120/90 120/80 100/70
38-0 37-5 37-0 37-0 36-0
90 80 80 80 70 399
24 22 20 20 20
400
Short Communications
By 18 :00 hr the entire left hand was swollen, the major dorsal surface vessels of the left arm ached, and the axillary lymph nodes were tender and swollen. At this time a deep, local pain was felt in the bitten phalanx of the index finger . Pain came in waves lasting 2 min, with 1 min of respite. Each wave began slowly, becoming nearly intolerable after 45 sec and abruptly terminating in another 75 sec. There was no feeling in the phalanx for the next 60 sec. Shortly after 18 :00 hr I was administered Valium and various pain killers by the Red Cross in Tapachula, Chiapas, M6xico . By 23 :00 hr pain continued as before and the hand appeared ecchymotic on the dorsal aspect. There were no indications of abnormal bleeding, bloody saliva, blood in urine, or prolonged bleeding from the first aid incisions. I was then admitted to a hospital where I received one vial of antivenine for Crotalus through i.m. injection in the right hip (type of serum not disclosed), cortisone, Valium, painkillers and other undetermined drugs. The next morning the finger, hand and arm ached, but pain was mild in contrast to the previous night. Swelling dissipated and color was nearly normal by 21 June. On the morning of 23 June the skin of the hand was nearly black, and remained so for 24 hr ; the skin began to dessicate at this time, appearing ashy and flaky, but returned to normal after another 15 days. I experienced a painful ache and parasthesia in the index finger and vessels of the left arm which awakened me each night until 9 July. Sensitivity began to return slowly to the numb finger and surrounding tissues by 10 July, and the hand appeared fully recovered by 31 July. I never experienced nausea or tingling other than that described. Table 1 lists some vital signs for the post bite period, courtesy of Hospital General B, Carmen de Acebo, Chiapas, M6xico . The top row, taken at rest, is presented for comparison. Abnormally high post-bite figures might be due to shock, ingestion of drugs and/or systemic effects of the venom. The toxic nature of Pliocercus saliva is consistent with SAVITSKY's (1978 : p. 317, Ph . D. diss., Univ . of Kansas) view that the venom of colubrid snakes is an element of a feeding strategy that is an alternative to constriction . During 12 laboratory feedings by two Pliocercus, I never observed these snakes to employ constriction . Salamanders and frogs were subdued and swallowed while the anterior portion of the snakes's body was held relatively straight ; prey were occasionally pinned against the wall or pressed against the substrate with the posterior part of the body while the snake's tail grasped another object for steadiness . Venom delivery systems of snakes need not be elaborate, and enlarged, grooved maxillary teeth are evidently non-essential (e.g., Rhabdophis is aglyphous) . TAUB (1967) conducted a histological investigation of the salivary glands of 180 species of colubrid snakes and found 163 of them to possess a Duvernoy's gland, considered homologous with the venom glands offront-fanged snakes (SAVITSKY, 1978 : p. 311, Ph . D. diss ., Univ. of Kansas). TAUB did not include Pliocercus in his survey, although it possesses enlarged, ungrooved rear maxillary teeth and a Duvernoy's gland (GREENE, personal communication) . MYERS (1974) believes that probably all species of Rhadinaea and the related genus Coniophanes may be venomous ; he considers Pliocercus to be a direct offshoot of the lateristriga species group of Rhadinaea. It is therefore not surprising that Pliocercus is also venomous, in light of this close phylogenetic relationship . Many colubrids probably have at least the potential to inflict a toxic bite. MINTON (1978) states that "with the exception of the boomslang, colubrids must hold on an appreciable time (several seconds) in order to inject venom," and ". . . that a quick defensive bite would not result in envenomation ." Pliocercus is an exception, and there may be others . The name "false coral snake" derives from an uncanny resemblance of Pliocercus to coral snakes, Micrurus, which it precisely parallels in pattern and coloration wherever
Short Communications
40 1
sympatric (GREENE and MCDIARMID, ms .) . Due to the deadly nature of Micrurus venom, Pliocercus has been thought a "presumptive Batesian mimic" of the coral snakes (HECHT and MARIEN, 1956 ; MERTENS, 1956 ; POUCH, 1964 ; GREENE, 1976). My observations show that Pliocercus can produce painful symptoms and, indeed, a single, rapid defensive bite is sufficient for a predator (including man) to learn to avoid such a snake . Pliocercus is best considered a mildly venomous Batesian or Mullerian model, and Micrurus probably contributes to the mimetic relationship in some undetermined capacity . Acknowledgements-1 am indebted to DIETER ENKERLIN, Director, Graduate School in Agriculture, lnstituto Tecnolbgico de Monterrey, Mbxico, and JACK REYNOLDS for their assistance after I was bitten . STEPHEN BUsACK, HARRY GREENE, SHERMAN MINTON, DONALD STRANEY and DAVID WAKE provided helpful criticism of the manuscript . Field work was supported by a grant from the Alexander Fund, Museum of Vertebrate Zoology, University of California, Berkeley . REFERENCES GREENE, H . W . (1976) Coral snake mimicry : does it occur? Herp. Rev. 7, 85 . HECHT, M . K . and D . MARIEN (1956) The coral snake mimicry problem : a reinterpretation . J. Morph . 98, 335 . KROLL, J . C . (1976) Feeding adaptations of hognose snakes . S West Nat. 20, 537. McKiNsTRY, D . M . (1978) Evidence of toxic saliva in some colubrid snakes of the United States . Toxicon 16,523 . MERTENS, R . (1956) Das Problem der Mimikry bei Korallenschlangen . Zool. Jb. (Syst.) 84, 541 . MINTON, S . A . (1978) Beware : nonpoisonous snakes . Nat . Hist. 87(9), 56. MINTON, S . A . and D . MESS (1978) Vier Bissfalle durch Colubriden . Salamandra 14, 41 . MITTLEMAN, M . B. and R . C . GoRis (1974) Envenomation from the bite of the Japanese colubrid snake Rhabdophis tigrinus (Boie). Herpetologica 30, 113 . MYERS, C. W. (1974) The systematics of Rhadinaea (Colubridae), a genus of new world snakes . Bull. Amer . Mus . nat . Hist . 153, 1 . NICKERSON, M . A . and R . W. HENDERSON (1976) A case of envenomation by the South American colubrid, Philodryas oljersi. Herpetologica 32, 197 . DOUGH, F . H . (1964) A coral snake "mimic" eaten by a bird . Copeia 1964, 223 . TAUB, A . M . (1967) Comparative histological studies on Duvernoy's gland of colubrid snakes . Bull. Amer. Mus. nat . Hist . 138, 1 . WELLMAN, J . (1963) A revision of snakes of the genus Coiwphis (family Colubridae, from middle America) . Univ. Kans. Pubis. Mus . nat . Hist . 15, 251 .
Tux . 18/3-u