Influential Factors of Local Tissue Necrosis after Taiwan Cobra Bites: A Secondary Analysis of the Clinical Significance of Venom Detection in Patients of Cobra Snakebites.

Chih-Chuan Lin,Shi-Ying Gao,Chung-Hsien Chaou

doi:10.3390/toxins13050338

Abstract

Local tissue swelling, inflammation, and wound necrosis are observed in Taiwan cobra bites. Knowledge of the factors influencing local tissue necrosis after cobra bites might improve the cobra bite treatment strategy. Therefore, we aimed to explore the factors influencing local tissue necrosis after cobra bites. This was a retrospective observational cohort study. All patients clinical presentations including serum venom levels for determining the influential factors in this study were obtained from Hung et al.’s previous study. Clinical features, such as bite information, initial swelling, patient presentation time, serum venom levels, and antivenom, use were extracted. The measurement outcome was the development of wound necrosis. The factors influencing wound necrosis were investigated using univariate and logistic regression analyses. The influential factors of local tissue necrosis and their areas under the curve were: initial limb swelling, 0.88; presentation time × serum level, 0.80; initial necrosis, 0.75; patient presentation time, 0.70. Serum venom level alone cannot be used as a predictive factor. The development of tissue necrosis might be associated with the venom factor, time factor, and their interaction. These influential factors can be used in future studies to evaluate antivenom efficacy.

Highlights

Cobra bites are a critical issue given that snakebite envenomation is considered a neglected tropical disease [1]
Key Contribution: We found that initial local swelling, initial necrosis, patient presentation time, and presentation time × serum level were associated with cobra bite-associated necrosis
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Summary

Introduction

Cobra bites are a critical issue given that snakebite envenomation is considered a neglected tropical disease [1]. Except for systemic neurotoxicity, different degrees of muscle weakness, paralysis, significant local tissue swelling, inflammation, and wound necrosis follow most cobra snakebites [2,3,4,5,6,7]. As one of the six medically important venomous snake species found in Taiwan, Taiwan cobra (Naja atra) envenomation accounts for approximately 20% of snakebite cases but with almost no mortalities [8]. When comparing its clinical effects with crotaline snake envenomation (Viridovipera stejnegeri and Protobothrops mucrosquamatus in Taiwan), Taiwan cobra envenomation causes more serious wound complications, such as local tissue swelling and necrosis (Figure 1), with few neurotoxic symptoms [9,10,11]. Cytotoxins of the three-finger toxin family are thought to cause wound necrosis after cobra bites [12]. It is accepted that higher cytotoxin doses may induce more extensive tissue necrosis [13]

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Conclusion