Snake bites in Taiwan

Abstract

Located at the juncture of tropical and subtropical regions, Taiwan has a warm and humid climate with abundant precipitation and food, which coupled with the island's diverse vegetation and landscape, makes it a suitable environment for many snake species. Among these, there are six kinds of poisonous snake with epidemiological significance. Three species induce hemorrhagic symptoms (Trimeresurus mucrosqua- matus, TM; Trimeresurus stejnegeri, TS; and Deinagkistrodon acutus, DA); two species induce neurotoxic symptoms (Naja naja atra, NA; and Bungarus multicinctus, BM); the other species induces hemorrhagic and neurotoxic symptoms (Vipera russelli formosensis. VR).The hemorrhagic venom causes disorders of the clot- ting cascade such as prolonged bleeding, primary fibrinolysis and disseminated intravascular coagulopathy. The neurotoxic venom provokes respiratory distress from weakened respiratory muscles, blurred vision, dip- lopia, dysarthria, dysphagia, dysphonia and paralysis of extremity muscles. The mixed envenomation mani- fests as a combination of neurotoxic and hemorrhagic effects previously described, as well as rhabdomyolysis and acute renal failure. The identification of snake species is important if antivenom is to be used. However, the species is not ably identified if the patient or companion fails to see or catch the responsible snake. Al- though these unidentifiable snakes could be non-venomous, venomous species are not uncommon. Therefore, guidelines for snakebite identification based on clinical symptoms and laboratory analysis is important to im- prove clinical diagnosis of snakebites. In Taiwan, T. stejnegeri bites are the most common. The second is T. mucrosquamatus. Naja naja atra is the third, Bungarus multicinctus is the forth and Vipera russelli formosen- sis is the fifth. Deinagkistrodon acutus is the least. Bites by Deinagkistrodon acutus and Vipera russelli for- mosensis generally occur in the south and east parts of the island. Aggressive antivenom treatment can reduce snakebite mortality rate, but for Bungarus multicinctus bites, maintaining the patient's airway and supporting their ventilation is vital to reducing mortality rate in addition to antivenom treatment. For dry bites or no en- venomation, the patient should be observed for at least 6 - 12 hours before discharged. The emergency physi- cian should determine the severity of envenomation and predominate venom activity before decide what type of antivenin to administer, how much, and over what period. History of exposure, local effect and systemic syndromes of envenomation, progression of symptoms and signs, laboratory data obtained in emergency de- partment should guide the decision for antivenom therapy. The freeze-dried antivenom was diluted with 50 - 100 mL of normal saline and infused intravenously for half to one hour. The poisonous snake bites in the lat- ter 4 hours to give the effect to be best, surpasses 8 hours only then to inject the effect to be bad. The dosage most toxicologists used for treating pediatric patients with snakebites was the same as that for adults. In gen- eral, 6 - 12 vials of antivenom against neurotoxic venom were used for Naja atra bite and 2 - 4 vials for Bun- garus multicinctus; 1 - 2 vials of antivenom against hemotoxic venom was used for Trimeresurus stejnegeri and 2 - 4 vials for Trimeresurus mucrosquamatus; 2 - 4 vials of anti-Deinagkistrodon acutus were used for Deinagkistrodon acutus and 2 - 4 vials of anti-Vipera russelli formosensis were used for Vipera russelli for- mosensis bite. During the infusion, the blood pressure, consciousness and skin reaction were evaluated. Keeping the varied clinical manifestations of snake bite in mind is important for effective management. Ready availability and appropriate use of antivenin, close monitoring of patients and institution of ventilatory support, all help reduce mortality.