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A bite by the Twin-Barred Tree Snake, Chrysopelea pelias (Linnaeus, 1758)

Ismail AK, Weinstein SA, Auliya M, Sabardin DM, Herbosa TJ, Saiboon IM, et al.

Clin Toxicol (Phila), 2010 Mar;48(3):222-6.
PMID: 20345298 DOI: 10.3109/15563650903550964

The Twin-Barred Tree Snake, Chrysopelea pelias, is a colubrine that, like other members of the genus Chrysopelea, is able to glide in the arboreal strata. Little is known about the effects of its bite. This report is the first clinically documented bite by this relatively uncommon rear-fanged species.

Matched MeSH terms: Snake Bites/physiopathology*
Non-front-fanged colubroid ("colubrid") snakebites: three cases of local envenoming by the mangrove or ringed cat-eyed snake (Boiga dendrophila; Colubridae, Colubrinae), the Western beaked snake (Rhamphiophis oxyrhynchus; Lamprophiidae, Psammophinae) and the rain forest cat-eyed snake (Leptodeira frenata; Dipsadidae)

Weinstein SA, Griffin R, Ismail AK

Clin Toxicol (Phila), 2014 Apr;52(4):277-82.
PMID: 24645905 DOI: 10.3109/15563650.2014.897352

Non-front-fanged colubroid snakes (NFFC; formerly and artificially taxonomically assembled as "colubrids") comprise the majority of extant ophidian species. Although the medical risks of bites by a handful of species have been documented, the majority of these snakes have oral products (Duvernoy's secretions, or venoms) with unknown biomedical properties/unverified functions and their potential for causing harm in humans is unknown.

Matched MeSH terms: Snake Bites/physiopathology*
The role of a point-of-care ultrasound protocol in facilitating clinical decisions for snakebite envenomation in Taiwan: a pilot study

Ho CH, Ismail AK, Liu SH, Tzeng YS, Li LY, Pai FC, et al.

Clin Toxicol (Phila), 2021 Sep;59(9):794-800.
PMID: 33605805 DOI: 10.1080/15563650.2021.1881535

BACKGROUND: The incidence of acute compartment syndrome (ACS) following snakebite envenomation may be seriously overestimated in Taiwan. Snakebite-induced ACS is difficult to determine solely by clinical examination. Snakebite patients previously underwent surgical intervention based on speculation and general clinical examinations suggesting ACS presentations instead of direct intracompartmental pressure (IP) measurement prior to fasciotomy. Point-of-care ultrasound (POCUS) is a relatively widely available noninvasive tool. This study aimed to evaluate snakebite-envenomated patients for the presence of subcutaneous edema and diastolic retrograde arterial flow (DRAF).
MATERIALS AND METHODS: Snakebite patients were prospectively recruited between 2017 and 2019. All patients were examined with POCUS to locate edema and directly visualize and measure the arterial flow in the compressed artery. The presence of DRAF in the compressed artery is suggestive of ACS development because when compartment space restriction occurs, increased retrograde arterial flow is observed in the artery.
RESULTS: Twenty-seven snakebite patients were analyzed. Seventeen patients (63%) were bitten by Crotalinae snakes, seven (26%) by Colubridae, one (4%) by Elapidae, and two (7%) had unidentified snakebites. All Crotalinae bit patients received antivenom, had subcutaneous edema and lacked DRAF in a POCUS examination series.
DISCUSSION: POCUS facilitates clinical decisions for snakebite envenomation. We also highlighted that the anatomic site of the snakebite is an important factor affecting the prognosis of the wounds. There were limitations of this study, including a small number of patients and no comparison with the generally accepted invasive evaluation for ACS.
CONCLUSIONS: We are unable to state that POCUS is a valid surrogate measurement of ACS from this study but see this as a starting point to develop further research in this area. Further study will be needed to better define the utility of POCUS in patients envenomated by snakes throughout the world.

Matched MeSH terms: Snake Bites/physiopathology
Geographical venom variations of the Southeast Asian monocled cobra (Naja kaouthia): venom-induced neuromuscular depression and antivenom neutralization

Tan KY, Tan CH, Sim SM, Fung SY, Tan NH

Comp Biochem Physiol C Toxicol Pharmacol, 2016 Jul-Aug;185-186:77-86.
PMID: 26972756 DOI: 10.1016/j.cbpc.2016.03.005

The Southeast Asian monocled cobras (Naja kaouthia) exhibit geographical variations in their venom proteomes, especially on the composition of neurotoxins. This study compared the neuromuscular depressant activity of the venoms of N. kaouthia from Malaysia (NK-M), Thailand (NK-T) and Vietnam (NK-V), and the neutralization of neurotoxicity by a monospecific antivenom. On chick biventer cervicis nerve-muscle preparation, all venoms abolished the indirect twitches, with NK-T venom being the most potent (shortest t90, time to 90% twitch inhibition), followed by NK-V and NK-M. Acetylcholine and carbachol failed to reverse the blockade, indicating irreversible/pseudo-irreversible post-synaptic neuromuscular blockade. KCl restored the twitches variably (NK-M preparation being the least responsive), consistent with different degree of muscle damage. The findings support that NK-T venom has the most abundant curarimimetic alpha-neurotoxins, while NK-M venom contains more tissue-damaging cytotoxins. Pre-incubation of tissue with N. kaouthia monovalent antivenom (NKMAV) prevented venom-induced twitch depression, with the NK-T preparation needing the largest antivenom dose. NKMAV added after the onset of neuromuscular depression could only halt the inhibitory progression but failed to restore full contraction. The findings highlight the urgency of early antivenom administration to sequester as much circulating neurotoxins as possible, thereby hastening toxin elimination from the circulation. In envenomed mice, NKMAV administered upon the first neurological sign neutralized the neurotoxic effect, with the slowest full recovery noticed in the NK-T group. This is consistent with the high abundance of neurotoxins in the NK-T venom, implying that a larger amount or repeated dosing of NKMAV may be required in NK-T envenomation.

Matched MeSH terms: Snake Bites/physiopathology