Neuromuscular action of venom from the South American colubrid snake Philodryas patagoniensis

Colubrid snake envenomation: Erythrolamprus bizona "false coral" snakebite - clinical aspects and importance of identifying mimics

Colubrids represent a diverse group of snakes historically regarded as harmless. With over 300 genera, the Colubridae family is the largest, encompassing approximately two-thirds of extant snake species. We describe a case of an 18-year-old male who suffered a colubrid snakebite from Erythrolamprus bizona, commonly known as the double-stranded coral snake mimic or false coral snake, which he misidentified as Lampropeltis sp., a fangless colubrid snake. Patient experienced localized erythema and edema, which later spread to the entire left hand along with moderate pain. Laboratory tests revealed leukocytosis and elevated creatine kinase. Symptoms resolved one week later. This case highlights the public health significance of ophidian accidents due to apparently "non-venomous snakes" or low-risk snakes such as the opisthoglyphous colubrid E. bizona. It also underscores the need to correctly identify and differentiate these snakes from other harmless colubrids, particularly double-stranded coral snake mimics in areas of geographic overlap and avoid their manipulation if uncertain of their taxonomic status.

A survey on some biochemical and pharmacological activities of venom from two Colombian colubrid snakes, Erythrolamprus bizona (Double-banded coral snake mimic) and Pseudoboa neuwiedii (Neuwied's false boa)

Colombian colubrid snake venoms have been poorly studied. They represent a great resource of biological, ecological, toxinological and pharmacological research. We assessed some enzymatic properties and neuromuscular effects of Erythrolamprus bizona and Pseudoboa neuwiedii venoms from Colombia. Proteolytic, amidolytic and phospholipase A₂ (PLA₂) activities were analyzed using colorimetric assays and the neuromuscular activity was analyzed in chick biventer cervicis (BC) preparations. The venom of both species showed very low PLA₂ and amidolytic activities; however, both exhibited high proteolytic activity, which in E. bizona venom surpassed that of P. neuwiedii venom. E. bizona and P. neuwiedii venoms provoked partial neuromuscular blockade, which was more prominent in P. neuwiedii venom. E. bizona venom (30 μg/ml) induced a significant potentiation of the contracture response to exogenous ACh (110 μM), which was not accompanied by twitch height alteration, whereas the highest venom concentration (100 μg/ml) inhibited contracture responses to both ACh and KCl (40 mM). In contrast, P. neuwiedii venom (30 and 100 μg/ml) caused significant reduction in the contracture responses to exogenous ACh and KCl. The morphological analyses showed high myotoxic effects in the muscle fibers of BC incubated with either venoms; however, they are more prominent in the P. neuwiedii venom. Our results suggest that the myotoxicity of the venom of the two Colombian species can be ascribed to their high proteolytic activity. An interesting data was the potentiation of the ACh-induced contracture, but not the twitch height, caused by E. bizona venom, at a concentration that is harmless to muscle fibers integrity. This phenomenon remains to be further elucidated, and suggest that a possible involvement of post-synaptic receptors cannot be discarded. This work is a contribution to expand the knowledge on colubrid venoms; it allows envisaging that the two venoms offer the potential to go further in the identification of their components and biological targets.

Biochemical and biological analysis of Philodryas baroni (Baron’s Green Racer; Dipsadidae) venom

Philodryas baroni—an attractively colored snake—has become readily available through the exotic pet trade. Most people consider this species harmless; however, it has already caused human envenomation. As little is known about the venom from this South American opisthoglyphous “colubrid” snake, herein, we studied its protein composition by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE), as well as its effects on the hemostatic system. Both reducing and nonreducing SDS-PAGE analysis demonstrated that the venom exhibits greatest complexity in the range of 50–80 kDa. The venom displayed proteolytic activity toward azocollagen, with a specific activity of 75.5 U mg−1, and rapidly hydrolyzed the Aα-chain of fibrinogen, exhibiting lower activity toward the Bβ- and γ-chains. The venom from P. baroni showed no platelet proaggregating activity per se, but it inhibited collagen- and thrombin-induced platelet aggregation. Prominent hemorrhage developed in mouse skin after intradermal injection of the crude venom, and its minimum hemorrhagic dose was 13.9 μg. When injected intramuscularly into the gastrocnemius of mice, the venom induced local effects such as hemorrhage, myonecrosis, edema, and leucocyte infiltration. Due to its venom toxicity shown herein, P. baroni should be considered dangerous to humans and any medically significant bite should be promptly reviewed by a qualified health professional.

Venomous snakebites in the Croatian North Dalmatia region

AIM

The aim of this research project is to analyze the epidemiological, clinical and laboratory attributes of venomous snakebites and to ascertain the timely and efficient treatment at the location where the incident took place or in varying clinical conditions.

METHODS

Epidemiological, clinical and laboratory data were collected from people who were bitten by venomous snakes as well as treatments at Zadar General Hospital during a span of eleven years (1999-2009) which were analyzed retrospectively.

RESULTS

During that period, 93 people were bitten by venomous snakes of which 57 patients (62%) were male and 36 (38%) were female. In 82 cases (90%), the bite area was localized on the limbs while in the remaining 11 cases the bite area was located elsewhere. At the time of the venomous snakebite, 31 (33%) patients were performing leisure activities and 44 (47.31%) of them were at work. The most common local snakebite signs are swelling and pain at the bite site (93 patients; 100%), hematomas and ecchymoses (87 patients; 89%). Of the affected patients, 8 suffered from compartment syndrome and one person (0.97%) expired.

CONCLUSION

Antivenom treatment for preventing possible allergic reactions should take place at the medical institution where the victim was transported. However, when transport is not immediately available or in cases where the victim shows clear signs of envenomation, antivenom treatment should be used immediately because its effect is weaker if the venom is allowed to run its course.