Epidemiology, clinical profile and management issues of cobra (Naja naja) bites in Sri Lanka: first authenticated case series

Abstract

In Sri Lanka, the Spectacled cobra (Naja naja) inflicts fatal bites. This hospital-based prospective study describes 25 cases of proven cobra bites, including 10 (40%) males and 15 (60%) females with a median age of 36 years (range 13-70 years). In 22 cases (88%) bites occurred in the daytime and in 13 cases (52%) they occurred at the victim's home compound. The site of the bite was the upper limb in 10 cases (40%), and 12 patients (48%) had applied a tourniquet. There were 5 dry bites (20%), 20 local reactions (80%), 9 cases of neurotoxicity (36%) and 3 cases of coagulopathy (12%). Eight patients (32%) had severe local necrosis-five underwent desloughing and skin grafting and two (including one of the above) had fasciotomy and compartmental decompression of the upper limb. Two patients died (case fatality rate 8%; 95% CI 0.98-26.03) due to rapidly spreading necrosis of the upper limb. Four patients (16%; 95% CI 4.53-36.08) developed respiratory paralysis; their median time from bite to assisted ventilation was 2h (range 2-5h) and the median duration of ventilation was 24h (range 18-24h). Envenomed patients received Indian polyvalent antivenom. The findings highlight the magnitude of local necrosis, respiratory paralysis and antivenom failure in Spectacled cobra bite in Sri Lanka. Coagulopathy requires verification with robust laboratory tests.

Pharmacokinetics of Naja sumatrana (Equatorial Spitting Cobra) Venom and Its Major Toxins in Experimentally Envenomed Rabbits

“…It belongs to α-neurotoxins with high intrinsic activity of inhibiting the motor endplate nicotinic receptors vis-à-vis that of cardiotoxins and phospolipases A 2 , the target receptors of which are primarily different and their actions are not crucial in mediating neuromuscular paralysis - the central cobra envenoming feature that leads to rapid death [34]. This is consistent with clinical reports where rapid onset of neuromuscular paralysis (caused by neurotoxins) is the most common fatal manifestation of systemic cobra envenomation, where victims may succumb to respiratory failure and death ensues within minutes to hours [9], [36], [45]. The pharmacokinetic result in addition to the neuromuscular blockade activity of neurotoxin generally supports the hypothesis that the neurotoxin plays the principal role in systemic envenomation of N. sumatrana , and should be one of the most crucial toxins to be targeted by antivenom.…”

Antivenom for Neuromuscular Paralysis Resulting From Snake Envenoming

“…This is well supported by clinical observations that neurotoxic snake envenoming almost exclusively results in flaccid paralysis [4,5,6,7,8,9,10,11,12] which is due to the blockade of neurotransmission at the neuromuscular junction by venom neurotoxins [13,14,15,16]. Neuromuscular paralysis in snake envenoming varies from mild to life threatening, depending on the degree of envenoming (i.e., quantity of injected venom reaching the circulation), the composition of the venom and potentially early therapeutic interventions.…”

An analysis of venom ontogeny and prey-specific toxicity in the Monocled Cobra (Naja kaouthia)

“…Intraspecific venom variation in the Spectacled Cobra (Naja naja) has resulted in the manifestation of different clinical envenomation symptoms and a lack of antivenom efficacy between India and Sri Lanka N. naja populations (Kularatne et al, 2009). The present study compares the biochemical composition of adult and juvenile N. kaouthia venoms and addresses the following questions: Are there differences in venom protein content and activity between adult and juvenile cobras?…”