Neuromuscular Effects of Common Krait (Bungarus caeruleus) Envenoming in Sri Lanka

PLoS Negl Trop Dis. 2016 Feb 1;10(2):e0004368. doi: 10.1371/journal.pntd.0004368. eCollection 2016 Feb.


Objective: We aimed to investigate neurophysiological and clinical effects of common krait envenoming, including the time course and treatment response.

Methodology: Patients with definite common krait (Bungarus caeruleus) bites were recruited from a Sri Lankan hospital. All patients had serial neurological examinations and stimulated concentric needle single-fibre electromyography (sfEMG) of orbicularis oculi in hospital at 6 wk and 6-9 mth post-bite.

Principal findings: There were 33 patients enrolled (median age 35 y; 24 males). Eight did not develop neurotoxicity and had normal sfEMG. Eight had mild neurotoxicity with ptosis, normal sfEMG; six received antivenom and all recovered within 20-32 h. Seventeen patients developed severe neurotoxicity with rapidly descending paralysis, from ptosis to complete ophthalmoplegia, facial, bulbar and neck weakness. All 17 received Indian polyvalent antivenom a median 3.5 h post-bite (2.8-7.2 h), which cleared unbound venom from blood. Despite this, the paralysis worsened requiring intubation and ventilation within 7 h post-bite. sfEMG showed markedly increased jitter and neuromuscular blocks within 12 h. sfEMG abnormalities gradually improved over 24 h, corresponding with clinical recovery. Muscle recovery occurred in ascending order. Myotoxicity was not evident, clinically or biochemically, in any of the patients. Patients were extubated a median 96 h post-bite (54-216 h). On discharge, median 8 days (4-12 days) post-bite, patients were clinically normal but had mild sfEMG abnormalities which persisted at 6 wk post-bite. There were no clinical or neurophysiological abnormalities at 6-9 mth.

Conclusions: Common krait envenoming causes rapid onset severe neuromuscular paralysis which takes days to recover clinically consistent with sfEMG. Subclinical neuromuscular dysfunction lasts weeks but was not permanent. Antivenom effectively cleared venom but did not prevent worsening or reverse neuromuscular paralysis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Animals
  • Antivenins / therapeutic use
  • Bungarotoxins / toxicity*
  • Bungarus*
  • Electromyography
  • Female
  • Humans
  • Male
  • Middle Aged
  • Nervous System / drug effects*
  • Neuromuscular Agents*
  • Paralysis / pathology*
  • Snake Bites / pathology*
  • Sri Lanka
  • Treatment Outcome
  • Young Adult


  • Antivenins
  • Bungarotoxins
  • Neuromuscular Agents

Grants and funding

This work was supported by an Australian National Health and Medical Research Council Project Grant (ID1030069). GKI is supported by a National Health and Medical Research Council Senior Research Fellowship ID1061041. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.