Enhydrina schistosa (Elapidae: Hydrophiinae) the most dangerous sea snake in Sri Lanka: three case studies of severe envenoming.

Sea snakes are highly venomous and inhabit tropical waters of the Indian and Pacific Oceans. Enhydrina schistosa is a common species of sea snake that lives in the coastal waters, lagoons, river mouths and estuaries from the Persian Gulf through Sri Lanka and to Southeast Asia. It is considered one of the most aggressive sea snakes in Sri Lanka where fishermen and people wading are at high risk. However, sea snake bites are rarely reported. In this report, we describe three cases where E. schistosa was the offending species. These three patients presented to two hospitals on the west coast of Sri Lanka within the course of 14 months from November 2011 with different degrees of severity of envenoming. The first patient was a 26-year-old fisherman who developed severe myalgia with very high creatine kinase (CK) levels lasting longer than 7 days. The second patient was a 32-year-old fisherman who developed gross myoglobinuria, high CK levels and hyperkalaemia. Both patients recovered and their electromyographic recordings showed myopathic features. The nerve conduction and neuromuscular transmission studies were normal in both patients suggesting primary myotoxic envenoming. The third patient was a 41-year-old man who trod on a sea snake in a river mouth and developed severe myalgia seven hours later. He had severe rhabdomyolysis and died three days later due to cardiovascular collapse. In conclusion, we confirm that E. schistosa is a deadly sea snake and its bite causes severe rhabdomyolysis.